89- Flurbiprofen, Comprehensive Profile

Abstract

Racemic flurbiprofen is one of the well-known forms of nonsteroidal anti-inflammatory drug (NSAID) substances. The enantiopure (S)-enantiomer exhibits a stronger anti-inflammatory activity (30-fold higher as compared to rac-flurbiprofen); however, flurbiprofen is still currently produced in large quantities as a racemic mixture. rac-Flurbiprofen is a NSAID used in the treatment of pain or inflammation in humans. Flurbiprofen is indicated for the management of vernal keratoconjunctivitis, postoperative ocular inflammation, herpetic stromal keratitis, excimer laser photorefractive keratectomy, and ocular gingivitis. Recent reports suggest potential topical and systemic use of flurbiprofen in radioprotection, the inhibition of colon tumor, the protection of postirradiation myelosuppression, pain management after foot surgery, and peridontal surgery. It is recognized that the enantiomers of biologically active compounds usually display different physiological activities. There has also been very rapid progress in asymmetric synthetic methods in recent years. As a result, increasing attention is being paid to the synthesis of nonracemic chiral drugs. One of the major groups of anti-inflammatory agents is the arylpropanoic acid, such as flurbiprofen, where the activity resides in the (S) isomers.

Full text

CHAPTER 4
Flurbiprofen
Alaa A.-M. Abdel-Aziz, Abdullah A. Al-Badr, and
Gamal Abdel Hafez
Contents 1. Description 114
1.1. Nomenclature 114
1.1.1. Systemic chemical names 114
1.1.2. Proprietary names 115
1.1.3. Nonproprietary names 115
1.2. Formulae 115
1.2.1. Empirical formula, molecular weight, and
CAS registry number 115
1.2.2. Structural formula 115
1.3. Elemental composition 115
1.4. Optical rotation 115
2. Uses and Applications 115
3. Method of Preparation 116
3.1. Synthesis of rac-flurbiprofen 117
3.2. Synthesis of (R)- and (S)-flurbiprofen 117
3.2.1. Chemical method for synthesis of
(R)- and (S)-flurbiprofen 117
3.2.2. Biocatalyzed enantioselective synthesis
of (R)- and (S)-flurbiprofen 119
4. Physical Characteristics 123
4.1. Melting point 123
4.2. Solubility 123
4.3. Appearance 123
4.4. Partition coefficient 123
4.5. Half-life 124
4.6. Volume of distribution 124
Profiles of Drug Substances, Excipients, and Related Methodology, Volume 37 #2012 Elsevier Inc.
ISSN 1871-5125, DOI: 10.1016/B978-0-12-397220-0.00004-0 All rights reserved.
Department of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, P.O. Box 2457, Riyadh,
Kingdom of Saudi Arabia
113

4.7. Clearance 124
4.8. Protein binding 124
4.9. Disposition in the body 124
5. Spectral Properties 124
5.1. Ultraviolet spectroscopy 124
5.2. Infrared spectroscopy 124
5.3. Nuclear magnetic resonance spectrometry 124
5.3.1.
1
H NMR spectra 125
5.3.2.
13
C NMR spectra 126
5.3.3. Solid-state nuclear magnetic resonance 126
5.3.4.
1
H MAS spectra 128
5.3.5.
13
C CP-MAS spectra and
1
H–
13
C HETCOR
maps 130
5.4. Mass spectrometry 133
6. X-Ray Powder Diffractometry 133
7. X-Ray Crystallography 137
7.1. Crystal structure of ()-2-(2-fluoro-4-biphenyl)
propionic acid (flurbiprofen) 137
7.2. Crystal structures and physical properties of
flurbiprofen salts 138
7.3. X-ray crystallographic determination of the
absolute configuration of (þ)-flurbiprofen
utilizing b-cyclodextrin complexation 139
8. Methods of Analysis 140
8.1. Compendial methods of analysis 140
8.1.1. United States Pharmacopoeia 140
8.1.2. British Pharmacopoeia 147
8.2. Reported methods of analysis 156
8.2.1. Spectrophotometric methods 156
8.2.2. Atomic absorption spectrometric
method 157
8.2.3. Potentiometric methods 157
8.2.4. Chromatographic methods 158
9. Pharmacodynamics 171
10. Pharmacokinetics 172
10.1. Metabolic pathway in human 173
10.2. Elimination profile in equine urine 174
Acknowledgments 177
References 177
1. DESCRIPTION
1.1. Nomenclature
1.1.1. Systemic chemical names
a-Methyl-a-(2-fluoro-4-biphenylyl) acetic acid
114 Alaa A.-M. Abdel-Aziz et al.

2-Fluoro-a-methyl-[1,10-biphenyl]-4-acetic acid
2-Fluoro-a-methyl-4-biphenyl-acetic acid
2-(2-Fluoro-4-biphenylyl) propionic acid
(1,1-Biphenyl)-4-acetic acid, 2-fluoro-a-methyl
3-Fluoro-4-phenylhydratropic acid [1–3]
1.1.2. Proprietary names
Flurbiprofen
1.1.3. Nonproprietary names
Ansaid, Antadys, Benactiv, Cebutid, Edolfene, Evril, Fenomel, Flurofen,
Froben, Ocufen, Ocuflur, Reupax, Strefen, Strepfen, Transact [1–3]
1.2. Formulae
1.2.1. Empirical formula, molecular weight, and CAS registry number
C
15
H
13
FO
2
,MW¼244.26, CAS¼5104-49-4
1.2.2. Structural formula
F
CH3
O
OH
1.3. Elemental composition
C¼73.76% H¼5.36% O¼13.1% F¼7.78%
1.4. Optical rotation
Optical rotations were measured on a JASCO DIP-1000 [4–7].
(S)-(þ)-Flurbiprofen, [a]
D22
¼þ45.6 (ethanol, c¼1.0) [4]
(S)-(þ)-Flurbiprofen, [a]
D20
¼þ44.6 (isopropanol, c¼1.0) [5]
(S)-(þ)-Flurbiprofen, [a]
D22
¼þ41.4 (CHCl
3
,c¼1.0) [6]
(S)-(þ)-Flurbiprofen, [a]
D20
¼1.46 (CH
2
Cl
2
,c¼2.5) [7]
2. USES AND APPLICATIONS
rac-Flurbiprofen is a nonsteroidal anti-inflammatory drug (NSAID) used
in the treatment of pain or inflammation, in humans [8–10]. Flurbiprofen
is indicated for the management of vernal keratoconjunctivitis [11],
Flurbiprofen 115

postoperative ocular inflammation [12], herpetic stromal keratitis [13],
excimer laser photorefractive keratectomy [14], and ocular gingivitis
[15]. Recent reports suggest potential topical and systemic use of flurbi-
profen in radio-protection [16], inhibition of colon tumor [17], protection
of postirradiation myelosuppression [18], pain management after foot
surgery [19], and peridontal surgery [20]. In 1993, its potent antiplatelet
activity was evaluated in a double-blind, placebo-controlled, multicenter
study for efficacy on preventing reinfarction and reocclusion after suc-
cessful thrombolysis or angioplasty in acute myocardial infarction [21].
Although it possesses a chiral center, with the S(þ)-enantiomer having
most of the beneficial activity, both enantiomers may possess analgesic
activity and all flurbiprofen preparations to date are marketed as the
racemate [8,22,23]. Flurbiprofen has been utilized since 1986 in the
North American market and demonstrates stereoselectivity in its phar-
macokinetics [24]. Inversion of (R)-()-flurbiprofen to its optical antipode
occurred to a variable extent in the dog (0.39) and the guinea pig (1.00)
and to a much lower extent in the rat (0.02) and the gerbil (0.05), and it
does not appear to undergo enantiomeric inversion in humans [25,26].
The mechanism of action is known to be the inhibition of prostanoid
biosynthesis via blocking of cyclooxygenase enzyme [10,27–29]. Cycloox-
ygenase (COX), also known as prostaglandin H synthase, is an enzyme
implicated in the mediation of pain, fever, and inflammation. It catalyzes
the oxidative conversion of arachidonic acid into prostaglandin H2, a key
intermediate in the biosynthetic pathway of prostaglandins, prostacy-
clins, and thromboxanes, which in turn mediate a variety of physiological
effects both beneficial and pathological [30]. Recently, it was discovered
that two COX isoforms exist: COX-l, expressed constitutively in many
tissues, and COX-2, an induced isoform having elevated expression in
inflamed tissues. COX-1 is thought to be involved in ongoing
‘‘housekeeping’’ functions, for example, gastric cytoprotection, while
COX-2 is the isoform implicated in the pathological effects mentioned
above [31]. Current COX inhibitors such as ibuprofen and flurbiprofen,
used as NSAIDs, inhibit both COX-1 and COX-2 [32]. The S(þ)-enantio-
mer of flurbiprofen inhibits prostanoid synthesis about 500 times more
potent than the R()-enantiomer [33].
3. METHOD OF PREPARATION
Racemic flurbiprofen is one of the well-known forms of the NSAID sub-
stance. The enantiopure (S)-enantiomer exhibits a stronger anti-inflam-
matory activity (as high as 30-fold higher compared to rac-flurbiprofen);
however, flurbiprofen is still currently produced in large quantities as a
racemic mixture.
116 Alaa A.-M. Abdel-Aziz et al.

3.1. Synthesis of rac-flurbiprofen
rac-Flurbiprofen 5was prepared from 3-fluoro-4-phenyl propiophenone
2which was prepared from (3-flouro-4-phenyl)phenyl bromide 1by
successive treatments with magnesium, propionaldehyde, and chromic
acid. Thus, the ketone 2was allowed to react with pyrrolidine to give the
pyrrolidine enamine 3, which on treatment with diphenyl phosphorazi-
date (DPPA) furnished the N-phosphorylated amidine 4. Hydrolysis of 4
with potassium hydroxide afforded rac-flurbiprofen (rac-5)[34] according
to the following scheme.
F
1
ON
H
BF
3
, toluene
reflux 38 h
33 %
F
2
C
N
CH
3
O
O
P
O
N
3
THF, rt. 1 h reflux 2 h
(68 %) F
4
CH
3
N
NP
O
O
O
KOH
HO-CH
2
CH
2
OH
reflux 8 h
30 %
F
rac-5
CH
3
COOH
Br
F
Mg, CH
3
CH
2
C
O
H
H
3
DPPA
3.2. Synthesis of (R)- and (S)-flurbiprofen
It is recognized that enantiomers of biologically active compounds usually
display different physiological activities. There has also been very rapid
progress in asymmetric synthetic methods in recent years. As a result,
increasing attention is being paid to the synthesis of nonracemic chiral
drugs. One of the major groups of anti-inflammatory agents is the arylpro-
panoic acid such as flurbiprofen where the activity resides in the (S) isomers.
The (R)-flurbiprofen was considered previously to be the inactive isomer
because it does not inhibit COX activity. However, recent studies have
revealed that it has antitumor effects [35,36] and can also reduce the level
of amyloid b-42 related to Alzheimer’s disease [37–39].Hence,itishighly
desirable to supply the market with the enantiopure of (S)- and (R)-
flurbiprofen.
3.2.1. Chemical method for synthesis of (R)- and (S)-flurbiprofen
3.2.1.1. Enantioselective synthesis of chiral flurbiprofen using chiral auxiliary
(R)- and (S)-3-hydroxy-4,4-dimethyl-l-phenyl-2-pyrrolidinone The
outlined synthetic strategy whereby asymmetry is introduced into the mole-
cules by the reaction of rac-2-(2-fluoro-4-biphenylyl)propanoyl chloride
(rac 6)with(R)-and (S)-3-hydroxy-4,4-dimethyl-l-phenyl-2-pyrrolidinone
Flurbiprofen 117

(R)- and (S)-5, in the presence of triethylamine, under standard esterification
conditions, gave (R,R)-7and (S,S)-7, respectively, with high diastereoselec-
tivity. Controlled acidic hydrolysis afforded the corresponding (R)-
or (S)-2-(2-fluoro-4-biphenylyl) propionic acid (flurbiprofen) with high
enantioselectivity [5] according to the following scheme.
N
CH3
CH3
OH
O
+CH
F
rac-6
CH3
C
O
Cl
(S)-5
(C2H5)3NNCH3CH3
CH3
O
O
(S,S)-7
2 N HCl, AcOH
120 °C, 2.5 h
CH
F
(S)-8
CH3
COOH
+(S)-5
N
CH3
CH3
OH
O
(R)-5
+CH
F
rac-6
CH3
C
(C2H5)3NN
CH3
CH3
O
(R,R)-7
2 N HCl, AcOH
120 °C, 2.5 h F
(R)-8
CH3
COOH +(R)-5
CH2Cl2
0°C 3h
O
CH2Cl2
0°C, 3h
O
C
O
F
Cl
O
F
C
H
CH3
Industrially, (R)-flurbiprofen is obtained via the following steps: (i)
synthesis of a suitable activated derivative of flurbiprofen, (ii) preparation
of the corresponding amide of (R,R)-thiomicamine to obtain a diastereo-
meric mixture, (iii) second-order asymmetric resolution, and (iv) hydro-
lysis of the optically pure amide. This process leads to a 73% yield [7].
3.2.1.2. Enantioselective synthesis of (S)-flurbiprofen via asymmetric dihy-
droxylation The aryl bromide was converted to the Grignard
reagent 9, and this reacted with acetone to give the alcohol 10 (75%)
[40,41]. Dehydration of this alcohol with MeSO
2
CI/Et
3
N gave the alkene
11 (83%) [42]. Asymmetric dihydroxylation of this alkene was achieved by
the use of AD (amix) to give the diol 12 (93%, 98% ee). The racemic diol
was obtained by OsO
4
/NMMNO oxidation of the alkene, and the enan-
tiomeric excess of the diol 12 was then determined by the use of chiral
shift NMR experiments on the derived mono primary acetates. Conver-
sion of the diol 12 to the monotosylate 13 and then treatment of the
tosylate with sodium hydride gave the epoxide 14 (76%) [43]. Catalytic
hydrogenolysis (10%Pd/C/EtOH/trace OH

)at40C gave the alcohol
118 Alaa A.-M. Abdel-Aziz et al.

15 (90%). Jones oxidation of the primary alcohol 15 gave (S)-(þ)-fiurbi-
profen 8, mp 108–110C (lit. [44] rac. 110–111 C), (56%, 98% ee). The
enantiomeric excess of flurbiprofen 8could not be determined from its
cinchonidine salt. Instead, it was converted to the methyl ester, and chiral
shift NMR experiments [6,45] on this derivative allowed the determina-
tion to be made, as in the following scheme.
MgBr
F
9
acetone
(75 %)
F
10
CH
3
CH
3
OH
H
3
CSCl
O
O
(C
2
H
5
)
3
N
(83 %) F
11
CH
3
CH
3
CH
3
CH
3
CH
2
AD mix α
(93 %) F
12
OH
OH TsCl
F
14
OH
OTs NaH
(76 %) F
13
O
10% Pd/C/C
2
H
5
OH/trace OH
–
–40 °C (90%) F
15
CH
3
OH
H
Jones oxidation
(56 %)
(
S
)
-8
COOH
CH
3
H
F
3.2.2. Biocatalyzed enantioselective synthesis of (R)- and
(S)-flurbiprofen
The kinetic resolution of (S)- or (R)-flurbiprofen has mainly been conducted
by chemical methods, such as the asymmetric synthesis of an (S)-enantio-
mer or the use of chiral chromatography and stereoselective crystallization
[46–48]; however, these methods entail expensive manufacturing processes
and are complex for industrial application.
Therefore, the use of biochemical processes for the kinetic resolution of
an optically active (S)- and (R)-enantiomers from its corresponding racemic
molecule using biocatalysts from a microbial origin has recently drawn
much attention [49–52]. Lipases (triacylglycerol acylhydrolase, E.C. 3.1.1.3)
are most commonly used as the biocatalyst for the enzymatic resolution of
an (S)-enantiomer [53,54]. For example, a lipase from Candida rugosa
was found to have a relatively high enantioselective activity toward the
(S)-flurbiprofen ester compared to other known lipases or esterases; how-
ever, the level of the enantiomeric excess was unsatisfactory [52,55].Plus,
the esterase PF1-K from the newly screened Pseudomonas sp. KCTC 10122BP
was found to effectively hydrolyze (S)-flurbiprofen ethyl ester into optically
pure (S)-flurbiprofen [52].
Immobilized lipase B from Candida antarctica (Novozym
Ò
435) has
been reported to exhibit a relatively high enantiopreference toward the
(R)-flurbiprofen, and it has been applied to the flurbiprofen resolution via
either esterification or transesterification in organic media [56,57]. It was
found that the enzymatic hydrolysis of rac-flurbiprofen methyl ester in
Flurbiprofen 119

aqueous-organic medium gave poor results. Transesterification of the
same ester mediated by immobilized lipase from Novozym
Ò
435 in
organic solvent proceeded with good enantiomeric excess, but the isola-
tion of the product required chromatographic separation and therefore
was unsuitable for large-scale preparation. Direct esterification of 4with
methanol in acetonitrile promoted by Novozym
Ò
435 proved to be the
best method since it gave, via a twofold kinetic resolution, S-flurbiprofen
with excellent enantiomeric excess. The R-flurbiprofen methyl ester
formed in the reaction can be converted into the starting rac-flurbiprofen
by alkaline hydrolysis or, alternatively, into R-flurbiprofen by hydrolysis
with acid [56–58] as in the following scheme:
CH3
COOH
F
rac-4
Candida antarctia
lipase
Methanol
CH3
COOCH3
F
(R)-16
+
CH3
COOH
F
(S)-8
In the past few years, the synthesis of ester bound has been reported by
different microorganisms used as dry mycelia [59,60].Drymyceliacan
show high enantioselectivity and stability to temperature and organic sol-
vent. Dry mycelia of molds are a precious source of enantioselective
enzymes with interesting economic and technological benefits, such as
improved stability while avoiding costly and time-consuming purifications
[59–61]. However, mycelia of Aspergillus oryzae display high enantioselec-
tivity toward (R)-flurbiprofen and can be efficiently used in pure organic
solvent for the resolution of (R,S)-flurbiprofen through esterification. The
use of the lyophilized mycelia facilitates the separation process so that in
one step the two enantiomers of flurbiprofen, which are both valuable for
pharmaceutical applications, can be easily separated. The biotransformation
can be carried out in different apolar solvents (i.e., n-heptane or toluene)
using different primary alcohols (i.e., ethanol or 1-octanol) as nucleophiles
under very mild conditions [7] according to the following scheme.
CH3
C
F
rac-4
+dry mycelia
CH3
F
(R)-17
1-Octanol
+
CH3
COOH
F
(S)-8
OH
O
O
OH
COOH
Thorpe and Caster [62] reported the following method for the prepa-
ration of flurbiprofen.
The Ullman condensation of 4-bromo-3-nitroacetophenone 1with
benzene in the presence of cupper gives 2-nitro-4-acetylbiphenyl
120 Alaa A.-M. Abdel-Aziz et al.

2which was reduced to the corresponding amino compound 3. This was
converted by the Schieman reaction into 2-fluoro-4-acetylbiphenyl 4
which by heating with sulfur and morpholine gives 2-fluoro-4-biphenyl-
acetic acid 5. Compound 5was converted to the ester 6by reluxing with
ethanol and sulfuric acid.
The reaction of ethyl 2-fluoro-4-biphenylyl acetate 6with diethyl car-
bonate and sodium ethoxide and then with dimethyl sulfate in ethanol
gives diethyl 2-fluoro-4-biphenylyl-a-methyl malonate 7which was
hydrolyzed with sodium hydroxide in ethanol and finally decarboxylated
at 180–200C to give flurbiprofen 8[62] as in the following scheme:
CH3
O2N
Br
O
Cu
4
3
2
1
O2N
O
CH3
12
reduction
H2N
O
CH3
3
Schieman reaction
FCOOC2H5
6
FCH3
4
O
HN
O
S, heat
FCOOH
5
EtOH
H2SO4
C2H5OOC
2H5, NaOC2H5
O
(1)
(2) Me2SO4
CF
C
7
C
H3C
(1) NaOH
(2) 180–200 °C
CH
F
COOH
CH3
8
OC2H5
OC2H5
O
O
Schlosser and Geneste [63] synthesized flurbiprofen by conversion of
3-fluorotoluene into 2-fluoro-4-methylbiphenyl 4with consecutive depro-
tonation and carboxylation of the benzylic methyl group and a-deproto-
nation followed by methylation to give flurbiprofen 6.
3-Fluorotoluene 1was treated with tert-butyl lithium and potassium
tert-butoxide in tetrahydrofuran and pentane, and after acidifying with
hydrochloric acid, 2-fluoro-4-methylbenzoic acid was produced 2. Treat-
ment of 2with fluorodimethoxyborane diethyl etherate and hydrochloric
acid gives 2-fluoro-4-methylphenylboronic acid 3. A solution of com-
pound 3with ethanol and aqueous solution of sodium carbonate were
added to bromobenzene, and tetrakis (triphenylphosphine) palladium
Flurbiprofen 121

gives 2-fluoro-4-methyl biphenyl 4. When compound 4was treated with
lithium diisopropylamine and potassium tert-butoxide and after acidifi-
cation with hydrochloric acid and extraction, 2-fluoro-4-biphenylyl acetic
acid 5was produced. At 75C, lithium diisopropylamine, tert-butoxide,
and 2-fluoro-4-biphenylyl acetic acid 5were added to a solution of butyl
lithium in tetrahydrofuran and hexane, and treatment with methyl iodide
gives flurbiprofen 6as in the following scheme:
CH3
F
tert-butyl
lithium
Pot. tert-butoxide
THF / H+
CH3
F
C
O
HO
Fluorodimethoxy
borane diethyl
etherate
/H
+
CH3
F
B
HO
HO
Br CH3
F
23
4
Lithium
diisopropylamine
tert-butoxide, butyl lithium
in THF, and hexane CH3I
Lithium
diisopropylamine
Pot. tert-butoxide
/H
+
CH2
F
5
C
O
OH
CH
F
6
COH
CH3
O
1
tetrakis (triphenyl
phosphine) palladium
Lu et al.[64] reported a procedure for synthesis of flurbiprofen via
Suzuki reaction catalyzed by palladium charcoal. 2,4-Difluoro nitroben-
zene 1was reacted with diethyl methylmalonate 2to give diethyl-2-(3-
fluoro-4-nitrophenyl)methylmalonate 3.Compound3was hydrolyzed and
decarboxylated to give 3-fluoro-4-nitro-a-methylphenyl acetic acid 4. Com-
pound 4was reduced to give 4-amino-3-fluoro-a-methylphenyl acetic
acid 5. Compound 5was converted to 4-bromo-3-fluoro-a-methylphenyl
acetic acid 6, and finally, compound 6was coupled with sodium tetra-
phenhylborate to give flurbiprofen 7according to the following scheme:
F
O2N
F
+HCCOOC2H5
COOC2H5
H3CNaOH, DMF
rt.
C
O2N
F
H3CCOOC2H5
COOC2H5CH3COOH, H2SO4
H2O, Δ
CH
O2N
F
CH3
COOH
12 3
4
H2/Pd/C, rt.
CH
H2N
F
CH3
COOH
5
NaNO2, 40 % HBr,
CuBr, H2O
CH
Br
F
CH3
COOH
6
Ph4BNa, Na2CO3
5% Pd/C, H2O
CH
F
CH3
COOH
7
122 Alaa A.-M. Abdel-Aziz et al.

Terao et al. [65] described an enzymatic method for the synthesis of
(R)-flurbiprofen. The drug was prepared from the corresponding malonic
acid derivative 3via asymmetric decarboxylation catalyzed by aryl mal-
onate decarboxylase (EC 4.1.1.76) in high chemical and optical yield.
Esterification of racemic flurbiprofen 1gives the racemic flurbiprofen
methyl ester 2. Treatment of the ester 2with lithium diisopropylamide
and methyl chloroformate gives dimethyl 3-fluoro-4-biphenylyl-methyl
malonate 3. Compound 3on hydrolysis gives the corresponding acid 4.
Compound 4on enzymatic decarboxylation gives (R)-flurbiprofen as in
the following scheme.
CH
COOH
CH
3
F
CH
3
OH, H
+
CH
COOCH
3
CH
3
F
lithium diisopropylamide,
ClCOOCH
3
C
COOCH
3
CH
3
F
COOCH
3
KOH/C
2
H
5
OH C
COOH
CH
3
F
COOH
Enzymatic
decarboxylation
CH
COOH
CH
3
F
12
34
5
90%
4. PHYSICAL CHARACTERISTICS
4.1. Melting point
Between 114 and 117C[3].
4.2. Solubility
Practically insoluble in water, freely soluble in most organic solvents. It
dissolves in aqueous solutions of alkali hydroxides and carbonates [3].
4.3. Appearance
A white (or almost white) crystalline powder [3].
4.4. Partition coefficient
logP(octanol/water) 4.2 [3].
Flurbiprofen 123

4.5. Half-life
Plasma half-life, 2–6h (mean 3.5) [3].
4.6. Volume of distribution
About 0.1L/kg [3].
4.7. Clearance
Plasma clearance, about 0.3mL/min/kg [3].
4.8. Protein binding
In plasma, about 99% [3].
4.9. Disposition in the body
Readily absorbed after oral administration, about 95% of a dose is
excreted in the urine in 24h, mainly as the 40-hydroxy, 30,40-dihydroxy,
and 40-methoxy metabolites, which are excreted partly as conjugates,
about 25% of a dose is excreted as unchanged drug [3].
5. SPECTRAL PROPERTIES
5.1. Ultraviolet spectroscopy
UV spectra of flurbiprofen in aqueous acid (Fig. 4.1) were scanned from
200 to 400nm, using UV/VIS spectrophotometer. Flurbiprofen exhibited
the maximum absorption at 247nm (Fig. 4.1)[3].
5.2. Infrared spectroscopy
The IR spectrum of rac-flurbiprofen as KBr disc is presented in Fig. 4.2 [66].
Principal peaks at wave numbers 1710, 1505, 1596, 1220, 743, 1230cm
1
(KBr disc). FTIR spectrum of (S)-flurbiprofen as (Nujol) was recorded on a
JASCO FTIR-200 as follows: 3000 (br), 1698, 1580, 1514, 1216, 765, 724, 698
cm
1
[7].
5.3. Nuclear magnetic resonance spectrometry
The
1
H and
13
C NMR spectra of (S)-flurbiprofen were registered with a
Varian Gemini 200 spectrometer (200MHz), and the
19
F NMR spectra
were recorded with a Bruker AC 200F (188MHz). Chemical shifts were
124 Alaa A.-M. Abdel-Aziz et al.

expressed in parts per million with respect to the tetramethylsilane signal
for the
1
H and
13
C NMR and Ar-CF
3
for
19
F[7]. The
1
H and
13
C NMR
spectra of rac-flurbiprofen were recorded on a Varian XL 500 MHz FT
spectrometer (Figs. 4.3–4.6).
5.3.1.
1
H NMR spectra
rac-Flurbiprofen,
1
H NMR (CDCl
3
): d1.67–1.69 (d, 3H, J¼6.5Hz, CH
3
),
3.90–3.93 (t, 1H, J¼7.0Hz, CH), 7.29–7.31 (d, 2H, J¼9.0Hz, H-Ph), 7.48–7.57
(m, 4H, H-Ph), 7.66–7.67 (d, 2H, J¼7.0Hz, H-Ph), 12.19 (s, 1H, COO-H,
exchange with D
2
O) (Figs. 4.3 and 4.4).
200
Absorbance
225 250 275 300 325 350 375 400
Wavelength (nm)
FIGURE 4.1 UV spectrum of flurbiprofen in ethanol [3].
100.0
Flurbiprofen RS156 Instrument: Dispersive Phase: Potassium bromide disc
80
60
40
20
0.0
Transmittance (%)
2000.0 1800
Wavenumber (cm
–1
)
1600 1400 1200 1000 800 600 400.0
FIGURE 4.2 Infrared spectrum of flurbiprofen (KBr disc) [66].
Flurbiprofen 125

(S)-Flurbiprofen,
1
HNMR(CDCl
3
): d1.59 (d, 3H, J¼7.3Hz, CH
3
), 3.85
(q, 1H, J¼7.1Hz, CH), 7.14–7.24 (m,2H, H-Ph), 7.38–7.60 (m, 6H, H-Ph) [7,67].
5.3.2.
13
C NMR spectra
rac-Flurbiprofen,
13
C NMR (CDCl
3
): d18.03, 45.04, 115.43, 115.62, 123.58,
123.80, 127.83, 128.25, 128.6, 128.69, 129.06, 129.08, 130.99, 131.02, 135.54,
141.05, 141.11, 158.87, 160.85, 180.77 (Figs. 4.5 and 4.6).
(S)-Flurbiprofen,
13
C NMR (CDCl
3
): d18.2, 45.0, 115.3, 115.8, 123.8, 123.9,
127.9, 128.2, 128.5, 128.6, 129.1, 129.2, 131.0, 131.1, 135.6, 141.0, 141.1, 157.4,
162.4, 179.6.
19
F NMR (CDCl
3
): d117.67 (dd, J
1
¼8.4Hz, J
2
¼11.3Hz) [7].
5.3.3. Solid-state nuclear magnetic resonance
All the high-resolution NMR experiments were performed on a Varian
Infinity Plus 400 double channel spectrometer operating at the
1
H Larmor
frequency of 399.89MHz and the
13
C frequency of 100.56MHz, equipped
with two CP-MAS probes for rotors with an outer diameter of 3.2 and 7.5
mm. Both the
13
C and
1
H90
pulses were 4.2 and 1.9ms for the 7.5 and 3.2
probes, respectively [68].
12.196
7.679
7.556
7.297
1.00
2.06
2.87
1.17
2.05
1.01
3.07
ppm–2–11234
5
678910111213 0
1.679
1.692
3.906
3.920
3.933
7.315
7.481
7.496
7.513
7.529
7.542
7.570
7.665
FIGURE 4.3
1
H NMR spectrum of rac-flurbiprofen in CDCl
3
.
126 Alaa A.-M. Abdel-Aziz et al.

The CP-MAS spectra have been recorded using constant radio fre-
quency power for both channels or a linear ramp for the
13
C channel
power during the contact time [69]. Continuous wave decoupling was
used for all samples except for flurbiprofen (FLU-A) and flurbiprofen
sodium salt (FLU-S), for which a SPINAL-64 decoupling scheme was
employed [70]. The CP-MAS spectra were recorded with a contact time
of 1–2ms and spinning frequencies of 5–7.5kHz. The HETCOR experi-
ments on FLU-A and FLU-S were both performed with 240 scans, 146
rows, and a contact time of 0.2ms, while the spinning rate was 6.5kHz for
FLU-A and 7.5kHz for FLU-S.
1
HT
1
relaxation time measurements were
performed through the
13
C-detected inversion recovery cross-polariza-
tion technique [71].
1
H MAS experiments were recorded at a spinning
frequency of 25kHz [68].
Both the resonance FID analysis and the
1
HT
1
measurements in low-
resolution conditions were performed on a single-channel Varian XL 100
spectrometer interfaced with a Stelar DS-NMR acquisition system: in this
7.670
4.985
4.971
3.912
1.682
1.668
25.02
8.27
1.10
65.61
91112131415 10 8 7 6 5 4 3 2 1 0
3.898
7.307
7.289
7.474
7.489
7.505
7.520
7.535
7.548
7.563
7.657
FIGURE 4.4
1
H NMR spectrum of rac-flurbiprofen (D
2
O exchange).
Flurbiprofen 127

case, the
1
H90
pulse length was 2.8ms.
1
H FIDs were recorded by means
of the Solid Echo technique [72], using an echo delay of 12 ms and a dwell
time of 1ms. The pulse sequence Inversion Recovery with attached solid
echo was used for measuring
1
HT
1
. All the measurements have been
performed at 25.00.2 C[68] (Fig. 4.7).
5.3.4.
1
H MAS spectra
Expansions of the
1
H MAS spectra of FLU-A and FLU-S, recorded at a
spinning frequency of 25kHz, are shown in Fig. 4.8, together with the
corresponding spectrum of RL.
The assignment of the peaks is quite straightforward: for FLU-A
(Fig. 4.8B) four different signals are clearly distinguishable, corresponding
to methyl (1ppm), methine (3ppm), aromatic (7ppm), and acidic (14
ppm) protons. Unfortunately, the residual linewidth does not allow a better
spectral resolution, and therefore, the different aromatic signals cannot be
distinguished [68].
180.77
160.85
158.87
141.11
141.05
135.77
135.54
135.30
131.02
130.99
129.08
129.06
128.83
128.69
128.57
128.36
128.25
127.98
127.83
123.83
123.80
123.58
115.62
115.43
77.43
77.18
76.92
45.04
18.03
ppm406080100120140160180200 20
FIGURE 4.5
13
C NMR spectrum of rac-flurbiprofen in CDCl
3
.
128 Alaa A.-M. Abdel-Aziz et al.

In the spectrum of FLU-S (Fig. 4.8A), the same group of resonances has
been observed, with the obvious exception of that due to the acidic protons.
However, some noticeable differences are present in the chemical shift
values between FLU-A and FLU-S, mainly concerning the peak of the
methyl protons. This difference (about 0.7ppm) is too large to be explained
with the sole different chemical structures between the two forms of FLU
131.02
115.63
115.44
131.00
129.31
129.07
128.71
128.58
128.39
127.99
127.84
127.53
123.84
123.82
124132 118 116 ppm120122130 128 126
FIGURE 4.6 An expansion of
13
C NMR spectrum of rac-flurbiprofen in CDCl
3
.
56
1
23
4CH
7
5⬘
4⬘
3⬘2⬘
1⬘
6⬘
CH3
COOH
F
O
H2C
CH2
O
C
N+
CH3
H3CCH3
CH3
CH2
H2C
C
OR2
O
R1
R1 = H, CH3
R2 = CH3, CH2-CH3
FIGURE 4.7 Chemical structures of FLU-A and Eudragit RL100 matrix (RL).
Flurbiprofen 129

and therefore suggests the presence of significant differences in either
conformational properties or molecular packing. The
1
HMASspectrum
of RL (Fig. 4.8C) shows three heavily superimposed peaks, and its inter-
pretation has been discussed in Ref. [73]: the signal at 1ppm is due to all the
aliphatic protons, with the exception of those close to the ester groups, that
give rise to the large resonance centered at about 3.5ppm, the narrow peak
at the same chemical shift arises instead from the protons of the trimethy-
lammonium groups, the minor linewidth being in agreement with the fast
dynamic processes experienced by these groups [68].
5.3.5.
13
C CP-MAS spectra and
1
H–
13
C HETCOR maps
The
13
C CP-MAS spectra of the acidic and sodium salt forms of FLU,
together with the corresponding spectrum of RL, are shown in Fig. 4.9,
while in Fig. 4.10, the
1
H–
13
C FSLG-HETCOR maps of FLU-A and FLU-S
are reported. The relatively small linewidths (about 100–150Hz) observed
in the
13
C spectra of FLU-A indicate that it is crystalline, confirming the
reported X-ray diffraction (PXRD) data [74], while slightly larger line-
widths (150–250Hz) are present in the spectra of FLU-S. This difference
could be in principle ascribable to a higher static disorder present in
FLU-S. However, other effects, as for instance differences in anisotropic
bulk magnetic susceptibility, possibly due to different degrees of aromatic
25 20 15 10 5
ppm
–10 –15
A
B
C
0–5
FIGURE 4.8
1
H-MAS spectra of (A) FLU-S, (B) FLU-A, and (C) RL. All the spectra were
acquired at a spinning speed of 25kHz [68].
130 Alaa A.-M. Abdel-Aziz et al.

stacking, cannot be ruled out and might themselves provide an explana-
tion of the experimental behavior [75,76].
The assignment of the
13
C spectrum of FLU-A (Fig. 4.9B) has been
previously reported [74], while for FLU-S (Fig. 4.9A), the interpretation of
the spectrum has been carried out on the basis of the comparison between
the
13
C CP-MAS spectra and the
1
H–
13
C HETCOR maps of the two drug
forms (Fig. 4.10). The resulting assignments are shown in Table 4.1.
In particular, the peaks resonating at 145.2 and 112.9ppm, exhibiting the
largest shifts with respect to the spectrum of FLU-A, have been assigned
to carbons 4 and 3, respectively, thanks to the FLU-S HETCOR map
(Fig. 4.10B). This has been possible by observing the strong correlation
between the carbons resonating at 145.2ppm and methane protons, and a
similar HETCOR correlation profile between the peak at 112.9ppm and
that ascribable to carbon 2 (158.6 and 161.3ppm), easily recognizable
because of the
1
J
C–F
doublet [68].
As already pointed out in the description of
1
H MAS spectra, also the
differences observed in the
13
C spectra and HETCOR maps of FLU-A and
100
ppm
50 0
8
A
B
C
8
3
3
4
4
2
2
*
**
*
7
7
200 150
FIGURE 4.9
13
C CP-MAS spectra of (A) FLU-S, (B) FLU-A, and (C) RL. The spinning speed
was 7.5 kHz for FLU-A and FLU-S and 5 kHz for RL. The labeling of the peaks refers to
Fig. 4.8. Asterisks denote spinning sidebands [68].
Flurbiprofen 131

9453
78
92
78
0
B
2.5
5
7.5
10
200 150 100
ppm
50 0
15
10
ppm
5
0
A
II
200 150 100
ppm
50 0
ppm
43
FIGURE 4.10
1
H–
13
C HETCOR maps of (A) FLU-A and (B) FLU-S. The correlation peaks
shown in the different regions, labeled by roman numbers in the map, were sampled at
different threshold levels for the sake of clarity, and the maximum peak intensities (in a.
u.) are 100 in I and 8 in II for FLU-A; 100 in I, 8 in II, and 5 in III for FLU-S. The correlation
peaks relative to
13
C spinning sidebands have been removed for simplifying the inter-
pretation of the maps. Both the experiments were performed using 146 rows and a
contact time of 0.2ms, while the spinning speed was 6.5kHz for FLU-A and 7.5 kHz for
FLU-S. The labeling of the
13
C peaks refers to Fig. 4.8 [68].
TABLE 4.1 Assignment of
13
C solid-state spectra for FLU-A and FLU-S [68]
13
C Chemical Shifts (ppm)
Nucleus FLU-A FLU-S
10136.4 136.2
2
a
157.7 158.6
160.2 161.3
3 116.9 112.9
4 140.2 145.2
5 123.5 –
7 46.4 50.2
8 16.0 17.8
9 183.9 184.4
1, 6, 20,3
0,4
0,5
0,6
0128.5 129.1
The labeling of the nuclei refers to Fig. 4.7.
a
The doublet observed for this carbon is due to the
1
J
C–F
scalar coupling [77].
132 Alaa A.-M. Abdel-Aziz et al.

FLU-S must be discussed not only in terms of their different chemical
structures, expected to mainly affect the chemical shifts of the signals of
the carbonyl and nearest aliphatic carbons, but also taking into account
possible different crystalline packing and conformational and dynamic
behavior, that can be particularly important in solid-state spectra [68].
By comparing the
13
C chemical shifts of FLU-A and FLU-S, several
differences can be outlined. Passing from FLU-A to FLU-S, some shifts
toward higher frequencies for aliphatic CH and CH
3
signals have been
recorded, qualitatively expected by replacing the carboxyl moiety with the
carboxylate one. However, these shifts are larger than those predicted by
semiempirical calculations for solution-state spectra, based on the mere
chemical structural changes (3.8 vs. 2.7 and 1.8 vs. 1.5ppm for methine
and methyl carbons, respectively). Nonetheless, the most significant differ-
ences are visible in the aromatic spectral region that should be substantially
unaffected by the different chemical structures. In particular, carbons 2 and
4 give rise to high-frequency shifts by about 1.0 and 5.0ppm, respectively,
while carbon 3 shifts toward lower frequencies by 4.0ppm. These changes
clearly indicate that FLU-A and FLU-S experience quite different confor-
mational and/or crystal packing situations, as already hypothesized on the
basis of
1
H spectra. This point could be further clarified by analyzing the
2D-HETCOR maps, showing dipolarly coupled proton–carbon pairs,
mostly determined by their spatial proximity. In addition to the correlation
expected on the basis of the chemical structure of FLU (for instance, the
methyl protons are obviously correlated to methyl, methane and carboxylic
carbons), there are other correlations that shed light on the molecular
conformational behavior. In particular, by looking at methyl protons, in
FLU-S, they are correlated with aromatic carbons 3 and 2, indicating that
the methyl group is closest to the side of the phenyl ring where the fluorine
atom is present. A very different situation has been observed in FLU-A,
where the same protons are correlated to the aromatic carbon 5, therefore
revealing that here the methyl group lies on the opposite part of the phenyl
ring, in agreement with the observed aromatic ring shifts [68].
5.4. Mass spectrometry
Mass spectra of (S)-flurbiprofen, carried out with electron impact method,
were registered at 70eV using a Ion Trap GCQ Finnigan mass spectrome-
ter (Fig. 4.11). EI (CHCl
3
): m/z244 [7]. Principal ions and their relative
intensities are presented in (Table 4.2).
6. X-RAY POWDER DIFFRACTOMETRY
The X-ray powder diffraction pattern of flurbiprofen was performed
using Simmons XRD-5000 diffractometer. Figure 4.12 shows the X-ray
powder diffraction pattern of flurbiprofen which was obtained on a
Flurbiprofen 133

pure sample of the drug substance. Table 4.3 shows the values for the
scattering angles (deg, 2y), the interplanar d-spacing (A
˚), and the relative
intensities (%) observed for the major diffraction peaks of flurbiprofen.
Diffraction patterns were recorded with a Philips diffractometer PW
1050/25 for powders. A voltage of 40kV and a current of 30mA for the
generator were used, with Cu as the tube anode material. The solids were
exposed to Cu Karadiation (a
1
¼1.54060A
˚and a
2
¼1.54439A
˚, with an a
1
/a
2
ratio of 0.5), over a range of 2yangles from 3to 30, at an angular speed of
0
50
51
100
%
57 6365
73
85 92
99
103
90 110
121 125
130 150
135
139
146
151153
157
165
152 170
177
170 190
195
197
209
210
219 226
200
245
244
246
250
m/
z
178
199
184
183
235
23070
77
78
FIGURE 4.11 Mass spectrum of flurbiprofen.
134 Alaa A.-M. Abdel-Aziz et al.

TABLE 4.2 Mass spectrum fragmentation pattern of flurbiprofen
m/zRelative intensity (%)
Fragment
Formula Ions
245 7.9 C
5
H
14
FO
2
Mþ1
244 37.8 C
15
H
13
FO
2
CH
F
+
COOH
CH3
229 0.2 C
14
H
10
FO
2
F
H
CO
+
OH
199 100 C
14
H
13
F
F
+
CH
CH3
(continued)

TABLE 4.2 (continued)
m/zRelative intensity (%)
Fragment
Formula Ions
184 15.7 C
13
H
9
F
F
+
CH
171 4.4 C
12
H
8
F
F
+
153 9.4 C
12
H
9
+
73 7 C
3
H
5
O
2
CO
+
CH3
CH
O H

1(2y) per minute, using divergence and receiving slits of 0.5or 1and
0.2, respectively. As Fig. 4.13 shows, PXRD analysis of pure flurbiprofen
showed the diffractographic profile of a crystalline product [74].
7. X-RAY CRYSTALLOGRAPHY
7.1. Crystal structure of ()-2-(2-fluoro-4-biphenyl) propionic
acid (flurbiprofen)
Data were collected on an automatic diffractometer with the y–2yscan-
ning technique (1.7scan in 2yat a scanning speed of 2min
1
) using Cu
Karadiation (l¼1–54,178A
˚, Ni filter). Unit-cell parameters were
6000
4000
2000
8.077
12.091
8.528
6.241
5.734
5.113
4.966
4.423 4.511
5.3555.536
4.115
4.275
3.732
3.947
4.056
3.819
3.325
3.280
3.144
3.043
3.002
2.959
2.875
2.915
2.765
2.630
2.485
2.412
2.349
2.238
2.171
2.066
1.908
1.838
1.778
3.483
3.439
0
10.0000 20.0000 30.0000 40.0000 50.0000 60.0000
2q (deg.)
Intensity (cps)
FIGURE 4.12 X-ray powder diffraction pattern of flurbiprofen.
TABLE 4.3 The X-ray powder diffraction pattern for flurbiprofen
Scattering
angle ()(2y)
d-Spacing
(A
˚)
Relative
intensity (%)
Scattering
angle ()(2y)
d-Spacing
(A
˚)
Relative
intensity (%)
7.305 12.0914 3827 23.270 3.8194 1008
10.365 8.5276 480 23.820 3.7324 2832
10.945 8.0769 2427 25.555 3.4828 1422
14.180 6.2407 428 25.885 3.4392 649
15.440 5.7342 765 26.790 3.3250 440
15.995 5.5364 2964 27.165 3.2800 756
16.540 5.3552 2304 28.365 3.1439 308
17.330 5.1128 109 29.325 3.0431 741
17.845 4.9664 126 29.740 3.0016 1361
19.665 4.5107 1578 30.175 2.9593 1563
20.060 4.4227 475 30.640 2.9154 162
20.760 4.2752 4553 31.085 2.8747 484
21.575 4.1155 2934 32.350 2.7651 215
21.895 4.0560 979 34.060 2.6301 802
22.510 3.9466 1481 36.420 2.4847 368
Flurbiprofen 137

determined from a least-squares fit of the coordinates of 12 reflections
which were individually centered on the diffractometer. During data
collection, three standard reflections were monitored after each 50 new
reflections had been measured. The monitored data gave no indication of
crystal deterioration [78].
The structure was solved by using a fragment of the molecule obtained
in an E map derived from the symbolic addition procedure as a partial
structure for the tangent formula in space group P1(Figs. 4.1 and 4.2).
The crystal data for C
15
H
13
O
2
F were, Pı
¯,a¼9.315 (4), b¼12.738 (9), and
c¼5.823 (2)A
˚,a¼83.0 (1), b¼107.2 (1), g¼107.0 (1),Z¼2, d
calc
¼1.29gcm
3
(Figs. 4.14 and 4.15).
7.2. Crystal structures and physical properties of
flurbiprofen salts
Flurbiprofen is bearing a carboxyl group. As the free acid its aqueous
solubility is only 0.03mg/mL. Hydrophobicity of the counter ion does not
fully determine the solubility of its amine salts, being 0.37, 2.80, 0.64, and
0.17mg/mL for the cyclohexyl (CH)-, hexyl-, octyl-, and adamantyl
FLU
5 10 15 [°2q]
20 25
FIGURE 4.13 X-ray diffraction patterns of pure flurbiprofen [74].
OO
F
F
FIGURE 4.14 Stereo configuration of the molecule drawn by program ORTEP.The heavy
atoms are shown at their final refined coordinates with anisotropic thermal parameters.
The hydrogens are drawn at their difference map coordinates with arbitrary isotropic
parameters [78].
138 Alaa A.-M. Abdel-Aziz et al.

(AD)-ammonium salts, respectively. DHof fusion is 159.0 J/g for the CH
but only 81.0J/g for the hexylammonium salt. It was reported that the
structures of the stable CH and AD salts, acquired with synchrotron
radiation because they exist as fine needles [79].
In both cases, the cycloalkyl group covers the twofold disordered fluor-
ophenyl ring, forming a clear hydrophobic domain. Hydrogen bonds join
three ammonium H atoms to two carboxylate O atoms and create infinite
ladders along the short b-axis, which in CH shows no thermal expansion,
while the a-axis expands by 1.9% over 141K (Table 4.4)[80,81].
7.3. X-ray crystallographic determination of the absolute
configuration of (þ)-flurbiprofen utilizing b-cyclodextrin
complexation
The crystal structure of the b-cyclodextrin complex with an optically
active (þ)-flurbiprofen was determined by the X-ray method to establish
the absolute configuration of the chiral guest molecules 4. The single
1.206
122.8
1.515
111.5
118.9
118.4
117.1
120.3
119.7
1.389
119.0
122.1
1.358
1.382
106.3
121.5
121.3 123.9
1288
1.534
111.8
1.387
O1 C14
C13
C15
1.552 C3
C4 C5
1.395
1.408
120.8
1.399
119.4
1.412
121.1
119.6
1.391
120.1
118.6
119.6 117.1 C6 C7
C8 C9
C10
C11
C12 1.397
120.3
1.376
120.3
1.491
1.400
F
C1
C2 1.381
O2
114.0
123.2
FIGURE 4.15 Bond distances and angles. The numbering scheme does not correspond to
the chemical numbering used to name the compound. Standard deviations are of the
order of 0.009A
˚for the bond lengths and 0.6for the bond angles [78].
TABLE 4.4 Crystal data of flurbiprofen salts [80,81]
Crystal, T(K) a(A
˚)b(A
˚)c(A
˚)b()r(mg/m
3
)
CH, 150 14.7991 6.3014 19.7845 91.273 1.237
CH, 291 15.0841 6.2988 19.8939 91.146 1.207
AD, 150 39.350 6.3973 16.9976 90 1.228
AD, 291 39.514 6.4257 17.1454 90 1.213
Flurbiprofen 139

crystal of (þ)-FP–b-CyD complex was prepared by slowly cooling a hot b-
CyD solution saturated with (þ)-FP. Lattice parameters and reflection
intensities were measured on a Nicolet P3/F diffractometer with graph-
ite-monochromated Cu Karadiation. By using the y–2yscan mode, 9639
independent reflections with [F
o
]3s(F) were obtained up to 117in 2y.
The crystal structure was deduced on the basis of the isomorphous
structure of n-propanol–b-CyD complex and refined by the block-diago-
nal least-squares method to the R-value of 0.095. Crystal data were as
follows: (C
42
H
70
O
35
C
15
H
13
O
2
F)
2
21H
2
O, F.W.¼3136.8, triclinic, space
group P1, z¼1, a¼15.446 (2), b¼15.513 (2), and c¼18.107 (2)A
˚,a¼113.52
(1),b¼99.32 (1),g¼102.89 (1),V¼3721.9 (7)A
˚
3
,D
x
¼1.40gcm
3
,D
m
¼
1.41gcm
3
(Fig. 4.16)[4].
8. METHODS OF ANALYSIS
8.1. Compendial methods of analysis
8.1.1. United States Pharmacopoeia [82]
Flurbiprofen contains not less than 99% and not more than 100.5% of
C
15
H
13
FO
2
, calculated on the dried basis.
FIGURE 4.16 Projection of the 2:2 (þ)FP–b-CyD complex. The atoms of the flurbiprofen
are drawn with shading, and the circles represent fluorine, oxygen, and carbon atoms in
the order of decreasing size [4].
140 Alaa A.-M. Abdel-Aziz et al.

Packaging and storage: Preserve in a tight container.
Identification
Test A: Infrared absorption: The test should be carried out as directed in
the general procedure h197Ki, the infrared absorption spectrum of a
potassium bromide dispersion of flurbiprofen previously dried, exhibits
maxima only at the same wavelength as that of a similar preparation of
USP Flurbiprofen RS.
Test B: Ultraviolet absorption: The test should be carried out as directed
in the general procedure h197Ui, the ultraviolet absorption spectrum of a
10mg/mL of flurbiprofen in 0.1N sodium hydroxide, absorption maxi-
mum at 247nm is about 0.8.
Melting range: The test should be carried out as directed in the
general procedure h741i, between 114 and 117C.
Loss on drying: The test should be carried out as directed in the
general procedure h731i. Dry flurbiprofen in a vacuum at 60 C to constant
weight: it loses not more than 0.5% of its weight.
Residue on ignition: The test should be carried out as directed in the
general procedure h281i, residue not more than 0.1%.
Heavy metal: The test when carried out as directed in the general
procedure ‘‘Method II’’ h231i, 0.001%.
Related Compounds
Diluent—Prepare a mixture of water and acetonitrile (11:9).
Mobile phase—Prepare a filtered and degassed mixture of water, aceto-
nitrile, and glacial acetic acid (12:7:1). Make adjustments if necessary (see
System Suitability under Chromatography in the general procedure h621i).
Standard stock solution—Dissolve an accurately weighed quantity of
USP Flurbiprofen-Related Compound A RS in Diluent to obtain a solution
having a concentration of about 50mg/mL.
System suitability solution—Pipet 2mL of Standard stock solution into a
10-mL volumetric flask, add about 20mg of USP Flurbiprofen RS, dilute
with Diluent to volume and mix.
Standard solution—Transfer 2 mL of Standard stock solution to a 10-mL
volumetric flask, dilute with Diluent to volume and mix.
Test solution—Prepare a solution of Flurbiprofen in Diluent containing
2mg/mL.
Chromatographic system (see Chromatography in the general procedure
h621i—The liquid chromatograph is equipped with a 254-nm detector
and a 3.9-nm15-cm column that contains 4-mm packing L1. The flow
rate is about 1mL/min. Chromatograph the System suitability solution and
record the peak responses as directed for Procedure: the relative retention
times are about 0.9 for flurbiprofen-related compound A and 1 for flurbi-
profen, and the relative standard deviation for replicate injections is not
more than 1%.
Flurbiprofen 141

Procedure—Separately inject equal volumes (about 20mL) of the Stan-
dard solution and the Test solution into the chromatograph, record the
chromatograms, and measure the areas for the major peaks. Calculate
the percentage of flurbiprofen-related compound A in the portion of
flurbiprofen taken by the formula:
100 Cs=CU
ðÞrU=rs
ðÞ
in which C
s
is the concentration, in mg/mL, of USP Flurbiprofen-Related
Compound A RS in the Standard solution,C
U
is the concentration, in
mg/mL of flurbiprofen in the Test solution, and r
U
and r
s
are the
peak responses for Flurbiprofen-Related Compound A obtained from
the Test solution and the Standard solution, respectively: not more
than 0.5% of flurbiprofen-related compound A is found. Calculate the
percentage of each impurity in the portion of flurbiprofen taken by
the formula:
100 ri=rs
ðÞ
in which r
i
is the peak response for each impurity obtained from the Test
solution, and r
s
is the sum of the responses of all the peaks obtained from
Test solution: the sum of all impurities is not more than 1%.
Assay—Dissolve about 0.5g of flurbiprofen, accurately weighed, in
100mL of alcohol, previously neutralized with 0.1 N sodium hydroxide
VS to the phenolphthalein end-point, add phenolphthalein TS, and titrate
with 0.1N sodium hydroxide VS to the first appearance of a faint pink
color that persists for not less than 30s. Each milliliter of 0.1 N sodium
hydroxide is equivalent to 24.43mg of C
15
H
13
FO
2
.
Flurbiprofen Tablets
Flurbiprofen tablets contain not less than 90% and not more than 110%
of the labeled amount of flurbiprofen (C
15
H
13
FO
2
).
Packaging and storage—Preserve in a well-closed container.
Identification
Test A: Place a number of tablets, equivalent to 100mg of flurbiprofen,
in a flask, add 10mL of 0.1N hydrochloric acid, and sonicate until the
tablets disintegrate. Extract with two 15-mL portions of ether, combining
the ether extracts in a flask containing about 1g of anhydrous sodium
sulfate. Decant the ether and evaporate to dryness: The IR absorption
spectrum of a mineral oil dispersion of the residue so obtained exhibits
maxima only at the same wavelengths as that of a similar preparation of
USP flurbiprofen RS.
Test B: The retention time of the flurbiprofen peak in the chromato-
gram of the Assay preparation corresponds to that in the chromatogram of
the Standard preparation, as obtained in the Assay.
142 Alaa A.-M. Abdel-Aziz et al.

Dissolution—Carry out the experiment as directed in the general
procedure h711i.
pH 7.2 Phosphate buffer—Dissolve 245g of monobasic potassium phos-
phate and 50g of sodium hydroxide in water to make 2000 mL of solution.
Dilute 333mL of this stock solution to 6000mL of water. If necessary,
adjust with 5N sodium hydroxide or with phosphoric acid to a pH of
7.200.05.
Medium: pH 7.2 phosphate buffer, 900mL.
Apparatus 2: 50rpm.
Time: 45min.
Procedure—Determine the amount of C
15
H
13
FO
2
dissolved from UV
absorbance at the wavelength of maximum absorbance at about 247nm on
filtered portions of the solution under test, suitably diluted with Dissolu-
tion Medium, in comparison with a Standard solution having a known
concentration of USP Flurbiprofen RS in the same Medium.
Tolerances—Not less than 75% (O) of the labeled amount of C
15
H
13
FO
2
is dissolved in 45min.
Uniformity of dosage units
To be carried out as described in the general procedure h9057i: meet
the requirements, the following procedure being used where the test for
Content Uniformity is required.
Procedure for content uniformity—Proceed as directed in the Assay,
except in preparing the Assay preparation to use 1 tablet and to use 10mL
of Internal standard solution for each 25mg of flurbiprofen in the tablet,
based on the labeled amount.
Assay
Mobile phase—Dissolve 1.4g of monobasic sodium phosphate in 570
mL of water, add 430mL of acetonitrile, and adjust with phosphoric acid
to a pH of 3. Filter and degas. Make adjustments if necessary (see System
suitability under Chromatography in the general procedure h621i).
Internal standard solution—Dissolve acetophenone in Mobile phase to
obtain a solution having a concentration of about 0.8 mL/mL.
Standard preparation—Accurately weigh about 30mg of USP Flurbiprofen
RS. Add 10mL of Internal standard solution and swill to dissolve. This stock
solution contains about 3mg of USP Flurbiprofen RS per milliliter. Dilute a
portion of this stock solution with 20 volumes of Mobile phase and mix.
Assay preparation—Place 3 tablets in a stoppered container. Based on
the labeled amount, in milligrams, of flurbiprofen in each tablet, add 25
mL of Internal standard solution for each 75mg of flurbiprofen in the three
tablets. Shake by mechanical means for about 15 min and centrifuge.
Dilute a portion of this solution with 20 volumes of Mobile phase and mix.
Chromatographic system (see Chromatography in the general procedure
h621i)—The liquid chromatograph is equipped with a 254-nm
Flurbiprofen 143

detector and a 4-mm X 25-cm column containing packing L7. The flow
rate is about 2mL/min. Chromatograph the Standard preparation and
record the responses as directed for Procedure: the relative retention
times are about 0.4 for acetophenone and 1 for flurbiprofen, the
resolution, R, between the acetophenone and flurbiprofen is not less
than 8, and the relative standard deviation for replicate injections is
not more than 2%.
Procedure—Separately inject equal volumes (about 20mL) of the Stan-
dard preparation and the Assay preparation into the chromatograph, record
the chromatograms, and measure the responses for the major peaks.
Calculate the quantity, in milligrams, of flurbiprofen (C
15
H
13
FO
2
) in the
portion of tablets taken by the formula:
WV=10ðÞRU=Rs
ðÞ
in which Wis the quantity, in milligrams, of USP Flurbiprofen RS used to
prepare the Standard preparation,Vis the volume, in milliliters, of Internal
Standard solution used to prepare the Assay preparation, and R
U
and R
s
are
the ratios of the flurbiprofen peak response to the acetophenone peak
response obtained from the Assay preparation and the Standard preparation,
respectively.
Flurbiprofen sodium
Flurbiprofen sodium contains not less than 97% and not more than
103% of C
15
H
12
FNaO
2
2H
2
O.
Packaging and storage—Preserve in well-closed containers.
USP Reference Standard: When carried out as directed in the general
procedure h11i—USP Flurbiprofen RS. USP Flurbiprofen sodium RS. USP
Flurbiprofen-Related Compound A RS.
Identification
Test A: Infrared absorption: The test should be carried out as directed in
the general procedure h197Mi. The infrared absorption spectrum of a
potassium bromide dispersion of flurbiprofen previously dried exhibits
maxima only at the same wavelength as that of a similar preparation of
USP Flurbiprofen RS.
Test B: Ultraviolet absorption: The test should be carried out as directed
in the general procedure h197Ui. The ultraviolet absorption spectrum of a
10mg/mL of flurbiprofen in pH 6 buffer consisting of 2.42 g of monobasic
sodium phosphate and 0.66g of dibasic sodium phosphate dissolved in
water to make 1000mL. Absorptivities at 246nm, calculated on the dried
basis, do not differ by more than 3%.
Test C: The residue obtained by igniting it meets the requirements of
the tests for Sodium as directed in the general procedure h191i.
Specific rotation, when the test is carried out as directed in the general
procedure h781Si: between 0.45and þ0.45.
144 Alaa A.-M. Abdel-Aziz et al.

Test solution: 50mg/mL, in methanol.
Loss on drying: Carry the test as directed in the general procedure
h731i—Dry about 0.3g of it in vacuum at a pressure not exceeding 1mm of
mercury over phosphorous pentoxide in a suitable drying tube at 60C for
18h: it loses not less than 11.3% and not more than 12.5% of its weight.
Heavy metals: The method should be carried out as directed in the
general procedure h231iMethod II: 0.001%.
Limit of flurbiprofen-related compound A
Diluent,Mobile phase, and System suitability preparation—Proceed as
directed in the Assay.
Standard solution—Use Standard flurbiprofen-related compound A prepara-
tion, prepared as directed in the Assay.
Test solution—Use the Assay preparation.
Chromatographic system—Proceed as directed in the Assay, except to
chromatograph the Standard solution instead of the Standard preparation.
Procedure—Separately inject equal volumes (about 20mL) of the Stan-
dard solution and the test solution into the chromatograph, record the
chromatogram, and measure the areas for the major peaks. Calculate the
percentage of flurbiprofen-related compound A in the portion of flurbi-
profen sodium taken by the formula:
200 C=WðÞrU=rs
ðÞ
in which Cis the concentration, in microgram per milliliter of USP
Flurbiprofen-Related Compound A RS in the Standard solution,Wis the
weight, in milligrams, of the portion of flurbiprofen sodium taken to
prepare the Test solution,andr
U
and r
s
are the peak areas for flurbiprofen-
related compound A obtained from the Test solution and the standardsolution,
respectively: not more than 1.5% is found.
Organic volatile impurities—Carry out this test as directed in the
general procedure h467iMethod I: Meets the requirements.
Assay
Diluents—Mix 500mL of methanol and 250 mL of water.
Mobile phase—Prepare a filtered and degassed mixture of acetonitrile,
water, and glacial acetic acid (50:49:1). Make adjustment if necessary (see
System Suitability under Chromatography as directed in the general proce-
dure h621i).
Standard flurbiprofen-related compound A preparation—Dissolve an accu-
rately weighed quantity of USP Flurbiprofen-Related Compound A RS in
methanol to obtain a stock solution having a known concentration of
about 150mg/mL. Transfer 1mL of this solution to a 200-mL volumetric
flask, dilute with Diluent to volume, and mix.
Standard preparation—Dissolve an accurately weighed quantity of USP
Flurbiprofen RS in methanol to obtain a stock solution having a known
Flurbiprofen 145

concentration of about 1mg/mL. Transfer 5mL of this solution to a 100-
mL volumetric flask, dilute with Diluent to volume, and mix.
System suitability preparation—Transfer 5 mL of the stock solution used
to prepare the Standard preparation and 2mL of the stock solution used to
prepare the Standard flurbiprofen-related compound A preparation to a 100-
mL volumetric flask, dilute with Diluent to volume, and mix.
Assay preparation—Transfer about 100 mg of flurbiprofen sodium,
accurately weighed, to a 100-mL volumetric flask, dissolve in and dilute
with methanol to volume, and mix. Transfer 5mL of this solution to a
second 100-mL volumetric flask, dilute with Diluent to volume, and mix.
Chromatographic system—See Chromatography in the general procedure
h621i: The liquid chromatograph is equipped with a 254-nm detector and a
4-mm25-cm col umn that contains 10-mm packing L7. The flow rate is about
2mL/min. Chromatograph the System suitability preparation and record the
peak responses as directed for Procedure: the resolution R, between flurbi-
profen-related compound A and flurbiprofen is not less than 1. Chromato-
graph the Standard preparation and record the peak responses as directed for
Procedure: The tailing factor is not more than 2.5, and the relative standard
deviation for replicate injections is not more than 1%.
Procedure—Separately inject equal volumes (about 20mL) of the Stan-
dard preparation and the Assay preparation into the chromatograph, record
the chromatograms, and measure the areas for the major peaks. Calculate
the percentage of C
15
H
12
FNaO
2
2H
2
O in the portion of flurbiprofen
sodium taken by the formula:
200 302:27=244:27ðÞC=WðÞrU=rs
ðÞ
in which 302.27 and 244.27 are the molecular weights of flurbiprofen
sodium dihydrate and anhydrous flurbiprofen, respectively, Cis the
concentration, in microgram per milliliter, of USP Flurbiprofen RS in the
Standard preparation,Wis the weight, in milligrams, of the portion of
flurbiprofen sodium taken to prepare the Assay preparation, and r
U
and
r
s
are the flurbiprofen peak responses obtained from the Assay preparation
and the Standard preparation, respectively.
Flurbiprofen Sodium Ophthalmic Solution
Flurbiprofen sodium ophthalmic solution contains not less than 90%
and not more than 110% of the labeled amount of flurbiprofen sodium
(C
15
H
12
FNaO
2
2H
2
O).
Packaging and storage—Preserve in a tight container.
USP Reference Standards:h11i—USP Flurbiprofen RS. USP Flurbi-
profen-Related Compound A RS.
Identification—The retention time for the major peak in the chromato-
gram of the Assay preparation corresponds to that in the chromatogram of
the Standard preparation, as obtained in the Assay.
146 Alaa A.-M. Abdel-Aziz et al.

pH—The test should be carried out as directed in the general proce-
dure h791i: between 6 and 7.
Antimicrobial effectiveness—The test should be carried out as
directed in the general procedure h51i: Meets the requirements.
Sterility—The test should be carried out as directed in the general
procedure h71i—It meets the requirements when tested as directed for
Membrane Filtration under Test for Sterility of the Product to be Examined.
Assay—Diluent,Mobile phase,Standard flurbiprofen-related compound
A preparation,Standard preparation, and System suitability preparation—
Proceed as directed in the Assay under Flurbiprofen sodium.
Assay preparation—Use the undiluted ophthalmic solution.
Chromatographic system—Proceed as directed in the Assay under Flur-
biprofen sodium using a 4-mm5-cm guard column that contains 5-mm
packing L1.
Procedure—Separately inject equal volumes (about 15mL) of the Stan-
dard preparation and the Assay preparation into the chromatograph, record
the chromatograms, and measure the areas for the major peaks. Calculate
the quantity of flurbiprofen sodium (C
15
H
12
FNaO
2
2H
2
O) in each millili-
ter of the ophthalmic solution taken by the formula:
302:27=244:27ðÞCr
U=rs
ðÞ
in which 302.27 and 244.27 are the molecular weights of flurbiprofen
sodium dihydrate and anhydrous flurbiprofen, respectively, Cis the
concentration, in milligram per milliliter, of USP Flurbiprofen RS in the
Standard preparation, and r
U
and r
s
are the peak responses obtained from
the Assay preparation and the Standard preparation, respectively.
8.1.2. British Pharmacopoeia [66]
Flurbiprofen contains not less than 99% and not more than the equivalent
of 101% of (2RS)-2-(2-fluorobiphenyl-4-yl)propanoic acid, calculated with
reference to the dried substance.
Identification
Test A. Melting point: The test should be carried out as directed in the
general procedure (2.2.14): 114–117C.
Test B. Dissolve 0.1g of flurbiprofen in 0.1 M sodium hydroxide and
dilute to 100mL with the same alkaline solution. Dilute 1 mL of the
solution to 100mL with 0.1M sodium hydroxide. Examined between 230
and 350nm, as directed in the general procedure (2.2.25), the solution
shows an absorption maximum at 247nm. The specific absorbance at the
maximum is 780–820nm.
Test C. Examine by infrared absorption spectrophotometry, as
directed in the general procedure (2.2.24), comparing with the spectrum
obtained with flurbiprofen CRS.
Flurbiprofen 147

Test D. Mix about 5mg with 45mg of heavy magnesium oxide R and
ignite in a crucible until an almost white residue is obtained (usually less
than 5min). Allow to cool, add 1mL of water R, 0.05 mL of phenolphthalein
solution R1, and about 1mL of dilute hydrochloric acid R to render
the solution colorless. Filter. To a freshly prepared mixture of 0.1 mL
of alizarin S solution R and 0.1mL of zirconyl nitrate solution R and 1 mL
of the filtrate. Mix, allow to stand for 5min, and compare the color of the
solution with that of a blank prepared in the same manner. The test
solution is yellow, and the blank is red.
TESTS
Appearance of Solution
Dissolve 1g of flurbiprofen in methanol R and dilute to 10 mL with the
same solvent. The solution is clear when the test is carried out as directed
in the general procedure (2.2.1) and colorless when the test is carried out
as directed in the general procedure (2.2.2 or Method 1).
Optical rotation, general procedure (2.2.7).
Dissolve 0.5g of flurbiprofen in methanol R and dilute to 20 mL with the
same solvent. The angle of optical rotation is 0.1to þ0.1.
Related substances
Examine by liquid chromatography, as directed in the general proce-
dure (2.2.29).
Test solution: Dissolve 0.2g of flurbiprofen in a mixture of 45 volumes
of acetonitrile R and 55 volumes of water R and dilute to 100 mL with the
same mixture of solvents.
Reference solution: (a) Dilute 1mL of the test solution to 50 mL with
a mixture of 45 volumes of acetonitrile R and 55 volumes of water R. Dilute
1mL of the solution to 10mL with a mixture of 45 volumes of acetonitrile R
and 55 volumes of water R.
Reference solution: (b) Dissolve 10mg of flurbiprofen impurity A CRS in a
mixture of 45 volumes of acetonitrile R and 55 volumes of water R and
dilute to 100mL with the same mixture of solvents. Dilute 10mL of this
solution to 100mL with a mixture of 45 volumes of acetonitrile R and 55
volumes of water R.
Reference solution: (c) Dissolve 10mg of flurbiprofen in a mixture of 45
volumes of acetonitrile R and 55 volumes of water R and dilute to 100 mL
with the same mixture of solvents. Dilute 1mL of the solution to 10 mL
with reference solution (b).
The chromatographic procedure may be carried out using:
(a) A stainless steel column 0.15m long and 3.9 mm in internal diameter
packed with octadecylsilyl silica gel for chromatography R (5mm)
(b) As mobile phase at a flow rate of 1mL/min a mixture of 5 volumes of
glacial acetic acid R, 35 volumes of acetonitrile R, and 60 volumes
of water R
(c) As detector a spectrophotometer set at 254nm
148 Alaa A.-M. Abdel-Aziz et al.

Inject 10mL of reference solution (c). Adjust the sensitivity of the
system so that the heights of the two principal peaks in the chromatogram
obtained are at least 40% of the full scale of the recorder.
The test is not valid unless the resolution between the peak
corresponding to impurity A and the peak corresponding to flurbiprofen
is at least 1.5.
Inject 10mL of the test solution and of reference solutions (a) and (b).
Continue the chromatography for twice the retention time of flurbiprofen.
In the chromatogram obtained with the test solution, the area of any
peak corresponding to impurity A is not greater than the area of the peak
in the chromatogram obtained with reference solution (b) (5%), the area of
any peak, apart from the principal peak and the peak due to impurity A, is
not greater than the area of the principal peak in the chromatogram
obtained with reference solution (a) (0.2%), and the sum of the areas of
any such peaks is not greater than five times the area of the principal peak
in the chromatogram obtained with reference solution (a) (1%). Disregard
any peak with area less than 0.1 times that of the principal peak in the
chromatogram obtained with reference solution (a) (0.02%).
Heavy metals, general procedure (2.4.8).
Dissolve 2g of flurbiprofen in a mixture of 10 volumes of water R and 90
volumes of methanol R and dilute to 20mL with the same mixture of
solvents. Twelve milliliters of the solution complies with the limit test B
for heavy (10ppm). Prepare the standard using lead standard solution (1ppm
Pb)obtainedbydilutinglead standard solution (100ppm Pb)Rwith a mixture
of 10 volumes of water R and 90 volumes of methanol R.
Loss on drying: general procedure (2.2.32).
Not more than 0.5%, determined on 1g of flurbiprofen by drying at
60C at a pressure not exceeding 0.7kPa for 3h.
Sulfated ash: general procedure (2.4.14).
Not more than 0.1%, determined on 1g of flurbiprofen in a platinum
crucible.
Assay
Dissolve 0.2g of flurbiprofen in 50mL of alcohol R. Titrate with 0.1 M
sodium hydroxide, determining the end-point potentiometrically as
directed in the general procedure (2.2.20). One milliliter of 0.1M sodium
hydroxide is equivalent to 24.43mg of C
15
H
13
FO
2
.
IMPURITIES
R⬘
COOH
R
CH3
and enantiome
r
Flurbiprofen 149

A. R¼R0¼H: (2RS)-2-(biphenyl-4-yl)propanoic acid,
B. R¼CH(CH
3
)COOH: 2-(2-fluorobiphenyl-4-yl)-2,3-dimethylbutane-
dioic acid,
C. R¼OH, R0¼F: (2RS)-2-(2-flurobiphenyl-4-yl)-2-hydroxypropanoic acid,
FR
D. R¼COCH
3
: 1-(2-fluorobiphenyl-4-yl)ethanone,
E. R¼COOH: 2-fluoro-biphenyl-4-carboxylic acid.
Flurbiprofen Sodium
Flurbiprofen Sodium is sodium (RS)-2-(2-fluorobiphenyl-4-yl)propio-
nate dihydrate. It contains not less than 98.5% and not more than 101.5%
of C
15
H
12
FNaO
2
, calculated with reference to the dried substance.
Identification
Test A. The infrared absorption spectrum according to the general test in
Appendix IIA is in concordance with the reference spectrum of flurbiprofen
sodium (RS 157).
Test B. Heat 0.2g over a flame until charred and then heat at 600C
for 2h. The residue yields the reactions characteristic of sodium salts.
Appendix VI.
TESTS
Related substances
Carry out the method for liquid chromatography, according to the
general procedure in Appendix IIID, using solutions in a mixture of
25 volumes of water and 50 volumes of methanol containing (1) 0.1%
(w/v) of flurbiprofen, (2) 0.0002% (w/v) of flurbiprofen, (3) 0.0005%
(w/v) of 2-(biphenyl-4-yl) propionic acid BPCRS, and (4) 0.0005% (w/v) of
flurbiprofen and 0.0005% (w/v) of 2-(biphenyl-4-yl) propionic acid BPCRS.
The chromatographic procedure may be carried out using:
(a) A stainless steel column (15cm3.9 mm) packed with stationary
phase C (5mm) (resolve 5mis suitable), (b) a mixture of 5 volumes of glacial
acetic acid, 35 volumes of acetonitrile, and 60 volumes of water as the mobile
phase with a flow rate of 1mL/min, and (c) a detection wavelength of 254
nm. Adjust the sensitivity so that the height of the principal peaks in the
chromatogram obtained with solution (4) is about 40% of full-scale deflec-
tion on the chart paper.
The test is not valid unless, in the chromatogram obtained with solu-
tion (4), the resolution factor between two principal peaks is at least 1.5.
In the chromatogram obtained with solution (1), the area of any peak
corresponding to 2-(biphenyl-4-yl) propionic acid is not greater than the
150 Alaa A.-M. Abdel-Aziz et al.

area of the peak in the chromatogram obtained with solution (3) (0.5%),
the area of any other secondary peak is not greater than the area of the peak
in the chromatogram obtained with solution (2) (0.2%), and the sum of the
areas of any secondary peaks is not greater than five times the area of the
peak in the chromatogram obtained with solution (2) (1%).
Heavy metals
Twelve milliliters of a 20% (w/v) solution in methanol complies with
limit test A for heavy metals, Appendix VII (10ppm). Use 10mL of the
solution obtained by diluting 10 mL of lead standard solution (20ppm Pb)
to 100mL with methanol to prepare the standard and 10mL of methanol
and 2mL of the solution of flurbiprofen sodium to prepare the reagent
blank.
Loss on drying
11.3–12.5% when determined by drying over phosphorous pentoxide at
60C at a pressure of 2kPa for 18h. Use 1g.
ASSAY
Carry out the method for liquid chromatography, Appendix IIID, using
solutions in a mixture of 25 volumes of water and 50 volumes of methanol
containing
(1) 0.015% (w/v) of flurbiprofen sodium,
(2) 0.015% (w/v) of flurbiprofen sodium BPCRS, and
(3) 0.00075% (w/v) of flurbiprofen sodium and 0.00075% (w/v) of
2-(biphenyl-4-yl) propionic acid PBCRS.
The chromatographic procedure described under related substance
may be used.
The assay is not valid unless, in the chromatogram obtained with
solution (3), the resolution factor between the two principal peaks is at
least 1.5. Calculate the content of C
15
H
12
FNaO
2
in flurbiprofen sodium
using declared content of C
15
H
12
FNaO
2
in flurbiprofen sodium BPCRS.
IMPURITIES
H
CH3
COOH
C
A. 2-(Biphenyl-4-yl) propionic acid
Flurbiprofen Eye Drops
Flurbiprofen Eye Drops are a sterile solution of flurbiprofen sodium in
purified water.
Flurbiprofen 151

IDENTIFICATION
Test A. Carry out the method for thin-layer chromatography, Appendix
IIIA, using silica gel GF
254
as the coating substance and a mixture of 5
volumes of propan-2-ol and 95 volumes of dichloromethane as the mobile
phase. Apply separately to the plate 5 mL of each of the following solu-
tions. For solution (1) dilute the eye drops, if necessary, with a mixture of
25 volumes of water and 50 volumes of methanol to produce a solution
containing 0.01% (w/v) of flurbiprofen sodium. Solution (2) contains
0.01% (w/v) of flurbiprofen sodium BPCRS in a mixture of 25 volumes of
water and 50 volumes of methanol. After removal of the plate, allow it to
dry in air and examine under ultraviolet light (254nm). The principal spot
in the chromatogram obtained with solution (1) corresponds to that in the
chromatogram obtained with solution (2).
Test B. In the Assay, the principal peak in the chromatogram obtained
with solution (1) has the same retention time as the principal peak in the
chromatogram obtained with solution (2).
TESTS
Acidity or Alkalinity
pH 6 and 7, Appendix VL.
2-(Biphenyl-4-yl) propionic acid
Carry out the method for liquid chromatography, Appendix IIID, using the
following solutions. For solution (1), dilute the eye drop, if necessary, with a
mixture of 25 volumes of water and 50 volumes of methanol to produce a
solution containing 0.03% (w/v) of flurbiprofen sodium. Solution (2) contains
0.00015% (w/v) of 2-(biphenyl-4-yl) propionic acid BPCRS in a mixture of 25
volumes of water and 50 volumes of methanol. Solution (3) contains 0.0005% of
flurbiprofen sodium BPCRS and 0.0005% (w/v) of 2-(biphenyl-4-yl) propionic acid
BPCRS in a mixture of 25 volumes of water and 50 volumes of methanol.
The chromatographic procedure may be carried out using (a) a stain-
less steel column (15cm3.9 mm) packed with stationary phase C (5mm)
(resolve 5mis suitable); (b) a mixture of 5 volumes of glacial acetic acid,35
volumes of acetonitrile, and 60 volumes of water as the mobile phase with a
flow rate of 1mL/min; and (c) a detection wavelength of 254 nm. Adjust
the sensitivity so that the height of the principal peaks in the chromato-
gram obtained with solution (3) is at about 40% of full-scale deflection on
the chart paper.
The test is not valid unless the resolution factor between the two princi-
pal peaks in the chromatogram obtained with solution (3) is at least 1.5.
In the chromatogram obtained with solution (1), the area of any peak
corresponding to 2-(biphenyl-4-yl) propionic acid is not greater than the
area of the peak in the chromatogram obtained with solution (2) (0.5%).
ASSAY
Carry out the method for liquid chromatography, Appendix IIID, using
the following solutions. For solution (1), dilute the eye drop, if necessary,
152 Alaa A.-M. Abdel-Aziz et al.

with a mixture of 25 volumes of water and 50 volumes of methanol to
produce a solution containing 0.015 (w/v) of flurbiprofen sodium. Solu-
tion (2) contains 0.015% (w/v) of flurbiprofen sodium BPCRS in a mixture of
25 volumes of water and 50 volumes of methanol. Solution (3) contains
0.0005% (w/v) of flurbiprofen sodium BPCRS and 0.0005% (w/v) of
2-(biphenyl-4-yl) propionic acid BPCRS in a mixture of 25 volumes of water
and 50 volumes of methanol.
The chromatographic procedure described under the test for 2-(biphe-
nyl-4-propionic acid may be used. The assay is not valid unless the
resolution factor between the two principal peaks in the chromatogram
obtained with solution (3) is at least 1.5. Calculate the content
of C
15
H
12
FNaO
2
2H
2
O in the eye drops using the declared content of
C
15
H
12
FNaO
2
2H
2
Oinflurbiprofen sodium BPCRS.
Flurbiprofen suppositories
Flurbiprofen suppositories contain flurbiprofen in a suitable supposi-
tory basis.
The suppository complies with the requirements stated under rectal prepara-
tions and with the following requirements.
Content of flurbiprofen C
15
H
13
FO
2
, 95–105% of the stated amount.
IDENTIFICATION
Test A. Carry out the method for thin-layer chromatography, Appendix
IIIA, using a silica gel F
254
precoated plate (Merck plates are suitable) and
a mixture of 10 volumes of glacial acetic acid, 10 volumes of methyl acetate,
and 80 volumes of trichloroethylene as the mobile phase but allowing the
solvent front to ascend 10cm above the line of application.
Apply separately to the plate 2mL of each of the following solutions.
For solution (1), cut a suitable number of the suppositories into small
pieces, add 50mL of methanol to a quantity containing 0.1 g of flurbiprofen,
heat gently until melted, shake mechanically for 10min, allow to cool at
2–8, filter (Whatman No. 1 paper is suitable) and evaporate to dryness.
Dissolve the residue in 5mL of a mixture of equal volumes of methanol and
water. Solution (2) contains 0.2% (w/v) of flurbiprofen sodium BPCRS in a
mixture of equal volumes of methanol and water. After removal of the
plate, allow to dry in air and examine under ultraviolet light (254nm). The
principal spot in the chromatogram obtained with solution (1) corre-
sponds to that in the chromatogram obtained with solution (2).
Test B. In the assay, the principal peak in the chromatogram obtained
with solution (1) has the same retention time as that in the chromatogram
obtained with solution (2).
Related substances
Carry out the method for liquid chromatography, Appendix IIID, using the
following solutions. For solution (1), cut a suitable number of the supposi-
tories into small pieces, add 50mL of methanol to a quantity containing 0.1g
of flurbiprofen, heat gently until melted, shake mechanically for 10min, and
Flurbiprofen 153

filter (Whatman No. 1 paper is suitable). Dilute the filtrate with sufficient of
a mixture containing 35 volumes of acetonitrile and 65 volumes of water to
produce 100mL and filter. For solution (2), dilute 1 volume of solution (1) to
100 volumes with a mixture of 45 volumes of acetonitrile and 55 volumes of
water and further dilute 1 volume to 5 volumes with the same solvent
mixture. Solution (3) contains 0.0005% (w/v) of 2-(biphenyl-4-yl) propionic
acid BPCRS in a mixture of 45 volumes of acetonitrile and 55 volumes of
water. Solution (4) contains 0.0005% of 4-acetyl-2-fluorobiphenyl BPCRS in a
mixture of 45 volumes of acetonitrile and 55 volumes of water. For solution
(5), dilute 1 volume of solution (1) to 200 volumes with solution (3).
The chromatographic procedure may be carried out using (a) a stainless
steel column (15cm3.9mm) packed with stationary phase C (5mm) (resolve
5mis suitable) fitted with a stainless steel guard column (2 cm4.6 mm)
packed with the same material; (b) a mixture of 5 volumes of glacial acetic
acid, 35 volumes of acetonitrile, and 60 volumes of water as the mobile phase
with a flow rate of 1mL/min; and (c) a detection wavelength of 254nm.
Adjust the sensitivity so that the heights of the principal peaks in the
chromatogram obtained with solution (5) are about 40% of full-scale
deflection on the chart paper.
The test is not valid unless, in the chromatogram obtained with solution
(5), the resolution factor between the two principal peaks is at least 1.5. In the
chromatogram obtained with solution (1), the area of any peak correspond-
ing to 2-(biphenyl-4-yl) propionic acid is not greater than the area of the
peak in the chromatogram obtained with solution (3) (0.5%), the area of any
peak corresponding to 4-acetyl-2-fluorobiphenyl is not greater than the area
of the peak in the chromatogram obtained with solution (4) (0.5%), the area
of any other secondary peak is not greater than the area of the peak in the
chromatogram obtained with solution (2) (0.2%), and the sum of the areas
any such peaks is not greater than 2.5 times the area of the peak in the
chromatogram obtained with solution (2) (0.5%).
ASSAY
Carry out the method for liquid chromatography, Appendix IIID,
using the following solutions. For solution (1), cut a suitable number of
the suppositories into small pieces, add 50mL of methanol to a quantity
containing 0.1g of flurbiprofen, heat gently until melted, shake mechani-
cally for 10min, and filter (Whatman No. 1 is suitable). Dilute the filtrate
with sufficient of a mixture containing 35 volumes of acetonitrile and 65
volumes of water to produce 100 mL, filter, and dilute 1 volume of the
filtrate to 25 volumes with the same solvent mixture.
Solution (2) contains 0.005% (w/v) of flurbiprofen sodium BPCRS in a
mixture of 35 volumes of acetonitrile and 65 volumes of water. Solution
(3) contains 0.0005% (w/v) of each of flurbiprofen sodium BPCRS and
2-(biphenyl-4-yl) propionic acid BPCRS in a mixture of 35 volumes of aceto-
nitrile and 65 volumes of water.
154 Alaa A.-M. Abdel-Aziz et al.

The chromatographic procedure described under related substances
may be used.
The assay not valid unless, in the chromatogram obtained with solu-
tion (3), the resolution factor between the two principal peaks is at least 1.5.
Calculate the content of C
15
H
13
NO
2
in the suppositories using the
declared content of C
15
H
13
FO
2
in flurbiprofen sodium BPCRS.
Flurbiprofen tablets
Flurbiprofen tablets contain flurbiprofen. They are coated.
The tablets comply with requirements stated under tablets and with the
following requirements.
Contents of flurbiprofen C
15
H
13
FO
2
, 92.5–107.5% of the stated
amount.
IDENTIFICATION
Extract a quantity of the powdered tablets containing 0.5 g of flurbi-
profen with 25mL of acetone, filter, evaporate the filtrate to dryness with
the aid of a current of air without heating, and dry at 60C at a pressure of
2kPa. The residue complies with the following tests.
Test A. The infrared absorption spectrum, Appendix IIA, is concordant
with the reference spectrum of flurbiprofen (RS 156).
Test B. Heat 0.5mL of chromic–sulfuric acid mixture in a small test tube,
in a water bath for 5min; the solution wets the side of the tube readily and
there is no greasiness. Add 2 or 3mg of the residue and heat in a water
bath for 5min, the solution does not wet the side of the tube and does not
pour easily from the tube.
Test C. Melting point, about 114C, Appendix VA.
Related substances
Carry out the method for liquid chromatography, Appendix IIID, using
the following solutions. For solution (1), disperse a quantity of the pow-
dered tablets containing 0.5g of flurbiprofen in 50mL water, add 200mL of
acetonitrile, mix, centrifuge, and use for the supernatant liquid. For solu-
tion (2) dilute 1 volume of solution (1) to 100 volumes with a mixture of 45
volumes of acetonitrile and 55 volumes of water and further dilute 1
volume to 5 volumes with the same solvent mixture. Solution (3) contains
0.001% (w/v) of 2-(biphenyl-4-yl) propionic acid BPCRS in a mixture of
45 volumes of acetonitrile and 55 volumes of water. For solution (4), dilute
1 volume of solution (1) to 200 volumes with solution (3).
The chromatographic procedure may be carried out using (a) a stain-
less steel column (15cm3.9 mm) packed with stationary phase C (5mm)
(resolve 5mis suitable); (b) a mixture of 5 volumes of glacial acetic acid,35
volumes of acetonitrile, and 60 volumes of water as the mobile phase with a
flow rate of 1mL/min; and (c) a detection wavelength of 254 nm.
Adjust the sensitivity so that the heights of the principal peaks in the
chromatogram obtained with solution (4) are about 40% of full-scale
deflection on the chart paper.
Flurbiprofen 155

The test is not valid unless the resolution factor between the two princi-
pal peaks in the chromatogram obtained with solution (4) is at least 1.5.
In the chromatogram obtained with solution (1), the area of any peak
corresponding to 2-(biphenyl-4-yl) propionic acid is not greater than the
area of the peak in the chromatogram obtained with solution (3) (0.5%),
the area of any other secondary peak is not greater than the area of the peak
in the chromatogram obtained with solution (2) (0.2%), and the sum of
the areas of any secondary peak is not greater than five times the area of the
peak in the chromatogram obtained with solution (2) (1%).
ASSAY
Weigh and powder 20 tablets. Shake a quantity of the powder containing
0.1g of flurbiprofen with 60mL of 0.1M sodium hydroxide for 5min, dilute to
100mL with 0.1M sodium hydroxide, filter if necessary, and dilute 10 mL of
the filtrate to 100mL with the same solvent. Further dilute 10–100mL with
the same solvent and measure the absorbances of the resulting solution at the
maximum at 247nm, Appendix IIB. Calculate the content of C
15
H
13
FO
2
taking 802 as the value of A (1%, 1cm) at the maximum at 247nm.
8.2. Reported methods of analysis
8.2.1. Spectrophotometric methods
El-Bagary [83] proposed an accurate and sensitive first derivative spec-
trophotometric method for the determination of flurbiprofen in bulk
powder and pharmaceutical dosage forms. The method is based on the
determination of fluoride content, after flurbiprofen had been treated by
the oxygen combustion flash method, using the first derivative spectro-
photometric technique of samples treated with zirconium (IV) chloride
and eriochrome cyanine R reagent against a blank with zero fluoride
concentration treated similarly.
Sajeev et al.[84] developed a new and rapid UV spectrophotometric
method and a reversed-phase high-performance liquid chromatographic
(HPLC) method for the quantitative estimation of flurbiprofen in pure
and in pharmaceutical dosage form. The column used in the liquid
chromatography was a reversed-phase 4.6 mm12.5cm (5mm) of LiChro-
CART Purospher end-capped C
18
LC column. The mobile phase was
methanol–acetonitrile–phosphate buffer (pH 5.6, 40:20:40) at a flow rate
of 0.75mL/min. The eluate was analyzed at a wavelength of 248 nm.
Chauthan et al.[85] developed a simple and sensitive ultraviolet spec-
trophotometric method for the estimation of flurbiprofen sodium in urine.
The method is based on extraction of the drug from urine sample using
chloroform after proper treatment. The chloroform extract shows absor-
bance maximum at 256nm and obeys Beer’s law in the concentration
range of 2–12mg/mL of the drug. No interference was observed from
the common metabolites present in the urine after proper extraction.
156 Alaa A.-M. Abdel-Aziz et al.

Baraka et al.[86] determined flurbiprofen and tiaprofenic acid by a
spectroscopic method. Both drugs reacted easily and quantitatively with
copper acetate forming bluish green precipitates. The drugs were deter-
mined calorimetrically by extracting the precipitates obtained in chloro-
form and measuring the absorbance at 686nm for flurbiprofen and 696nm
for tiaprofenic acid. To improve the sensitivity of the method, the pre-
cipitates of the drugs with copper were dissolved in the least amount of
dilute ammonia and the copper content was determined via reaction with
sodium diethyldithiocarbamate. The yellow solution was measured at
477nm. The method was applied for the determination of the drugs in
pharmaceuticals, and the results obtained were in good agreement those
of the official methods.
Wang et al.[87] determined flurbiprofen by a micellar-sensitized fluo-
rescence spectrometric method. The experiments indicated that sodium
dodecyl sulfate can enhance greatly the fluorescence signal. Based on
these results, a new method of sensitized fluorescence using the micellar
system for the trace analysis of flurbiprofen was developed. The linear
range was 210
8
to 2.510
6
mol/L. The recovery of sample was within
the range of 99.2–100%, and relative standard deviation was 1.8%.
8.2.2. Atomic absorption spectrometric method
Baraka et al.[86] determined flurbiprofen by an atomic absorption spec-
trometry procedure through the determination of the copper content of
the precipitate. The optimum conditions for precipitation were carefully
studied. The molar ratio of the reactants was ascertained. Statistical anal-
ysis of the results obtained was compared with the official methods. The
results were of equal accuracy and reproducibility.
8.2.3. Potentiometric methods
Bunaciu et al.[88] constructed an ion-selective electrode (ISE) response
characteristic (slope, intercept, linear range, and detection limit) for flur-
biprofen using a computer program, written in TurboPascal 5.5. The
sensor response characteristics were evaluated for selectivity coefficients
and quantitative determinations.
Bunaciu et al.[89] prepared another ion-selective membrane electrode
for flurbiprofen using a PVC membrane impregnated with the ion pair
complex formed between the tricaprylmethylammonium chloride cation
and the flurbiprofen anion. The electrode was used for the determination
of flurbiprofen in Froben 50 and Froben 100 by a standard addition
method at pH 6.8. The calibration graph for flurbiprofen was linear for
70mM to 10mM, and the detection limit was 41mM. The RSD (n¼4) for the
determination of flurbiprofen in tablets was h2%).
Flurbiprofen 157

8.2.4. Chromatographic methods
8.2.4.1. Thin-layer chromatography Dhaves et al.[90] added plasma
(1mL) to flurbiprofen, 1mL 3M HCl was added and extracted with 5 mL
hexane/diethyl ether (4:1) twice. The pooled extract was dried, and the
residue was dissolved in 500mL methanol. A portion (20 mL) was spotted
on to an Al silica gel 60F 254 plate for development with n-hexane/ethyl
acetate/glacial acetic acid (6:3:1) as mobile phase, a 10-min run time and
UV detection at 247nm. The calibration graph was linear from 40 to 800ng
flurbiprofen, with a detection limit of 20ng and RSD of <4% (n¼6).
Recoveries were 87.2–87.9%.
Clarcke [3] recommended the following seven systems:
(1) Plates: Silica gel G, 250-mm thick.
Mobile phase, ethyl acetate.
Reference compounds: hydrochlorothiazide R
F
¼11, sulfafurazole
R
F
¼33, salicylamide R
F
¼52, prazepam R
F
¼72.
R
F
¼45.
(2) Plates: Silica gel G, 250-mm thick.
Mobile phase, chloroform:cyclohexane:acetic acid (4:4:2).
R
F
¼69.
(3) Plates: Silica gel G, 250-mg thick.
Mobile phase, chloroform:methanol:propionic acid (72:18:10).
R
F
¼91.
(4) Plates: Silica gel G, 250-mm thick.
Mobile phase, chloroform:acetone (80:20).
Reference compounds: paracetamol R
F
¼15, clonazepam R
F
¼35.
Secobarbital R
F
¼55, methylphenobarbital R
F
¼70.
R
F
¼30.
(5) Plates: Silica gel G, 250-mm thick.
Mobile phase, ethyl acetate:methanol:strong ammonia solution
(85:10:5).
Reference compounds: sulfamidine R
F
¼13, hydrochlorothiazide
R
F
¼34, temazepam R
F
¼63, prazepam R
F
¼81.
R
F
¼6.
(6) Plates: Silica gel G, 250-mm thick.
Mobile phase, ethyl acetate.
Reference compounds: Sulfathiazole R
F
¼20, phenacetin R
F
¼38,
salicylamide R
F
¼55, secobarbital R
F
¼68.
R
F
¼30.
(7) Plates: Silica gel G, 250-mm thick.
Mobile phase, ethyl acetate:methanol:strong ammonia solution
(80:10:10).
R
F
¼16.
158 Alaa A.-M. Abdel-Aziz et al.

8.2.4.2. Liquid chromatography Santoro et al.[91] developed and vali-
dated a chiral liquid chromatographic method for the rapid quantitative
determination of flurbiprofen enantiomers in pharmaceutical preparations.
Baseline resolution of R-andS-flurbiprofen was achieved on a [(3S,4S)-
4-(3,4-dinitrobenzamido)-1,2,3,4-tetrahydro-phenanthrene] coated on 5mm
silica gel column with mobile phase of hexane–ethanol–acetic acid
(950:50:2). The standard curve of S-flurbiprofen showed good linearity
over the concentration range from 2 to 8mg/mL with correlation coefficient
of 0.9993. The intraday precision of the sample, determined at two concen-
tration levels (8 and 20mg/mL of racemic flurbiprofen), was 0.16 and 0.23
for R-flurbiprofen and 0.14 and 0.46 for S-flurbiprofen. The intraday accu-
racy of the sample expressed as percentage recovery was 100.1% and
100.4% for R-andS-flurbiprofen, respectively. The results showed preci-
sion, accuracy, and specificity of the method for the analysis of S-flurbipro-
fen in pharmaceutical formulation.
8.2.4.3. Miceller electrokinetic capillary chromatography Zhang et al.[92]
used a micellar electrokinetic capillary chromatography method for the
determination of flurbiprofen in rabbit plasma. Rabbit plasma (0.2 mL)
was deproteined by methanol which was then evaporated under nitrogen
flow. The residue was resolved by methanol for injection. The electropho-
retic conditions were as follows: 75-mm100-cm capillary tube, buffer:
20mmol/L of borate solution containing 20mmol/L of sodium dodecyl
sulfate. The method using ketoprofen as an internal standard was linear in
the range of 1–24mg/mL of flurbiprofen with good precision. The added
recovery of 2.4, 7.2, and 12mg was 95.36%, 93.55%, and 95.22%, respectively,
and the detection limit was 0.2mg/mL. The method is accurate, simple and
can be used for the pharmacokinetic study of flurbiprofen.
8.2.4.4. Gas chromatography Clarcke [3] recommended the following
three systems:
(1) Packed column: 3% SE-30 or OV-1 on 80–100 mesh Chromosorb G
HP (acid-washed and dimethyldichlorosilane-treated), 2 m2mm
i.d. glass column, it is essential that the support be fully deactivated.
Column temperature: Normally between 100 and 300C, for iso-
thermal conditions, an approximate guide to temperature is to use
RI10.
Carrier gas: Nitrogen at 45mL/min.
Capillary column: 10–15m0.32 or 0.53mm i.d., 100% dimethyl-
PSX (X-1) with a 1.5- to 3-mm film thickness.
Carrier gas: Helium.
Flurbiprofen 159

Temperature program, 4min at 135C, 13C/min to 200 C,
6C/min to 312C, 6min final hold.
Retention index: 1900.
(2) Column: SE-30 on 80–100 mesh Chromosorb G (acid-washed and
dimethyldichlorosilane-treated), 2m3mm i.d. glass column.
Column temperature: 120C for 2 min and then programmed at
10C/min to 260C and held for 5 min.
Carrier gas: Nitrogen at 40mL/min.
Reference compound: Hexadecane (n-C
16
H
34
).
Retention index¼1.3.
(3) Column: HP1 (methyl-PSX) 12m0.2mm i.d. fused-silica capillary,
0.33mm film thickness.
Injector: 280C splitless mode.
Column temperature: 100C for 2 min and then programmed at
30C/min to 310C and held for 8min.
Carrier gas: Helium, constant flow 1mL/min.
Retention index: 1880.
8.2.4.5. High-performance liquid chromatography Snider et al.[93] devel-
oped an HPLC method with an automated sample extraction for the
determination of flurbiprofen and ibuprofen in dog serum. Sample
extraction was automated by use of cartridges packed with a styrene–
divinylbenzene macroreticular resin in a microprocessor-controlled cen-
trifugal system. The average recoveries were 98.9% for flurbiprofen. The
limits of detection were approximately 0.04 mg/mL for flurbiprofen
at 254nm. The relative standard deviation for the determination of a
laboratory standard between days was 2.4% (20 mg/mL) for flurbiprofen.
Peak height ratios were linear with concentrations of 0.04–100 mg/mL
for flurbiprofen. The method is simple, rapid sensitive, and specific.
The use of an automated sample preparation procedure improved the
between-day precision by a factor of 2 when compared to a manual
extraction procedure. The method was applied to bioavailability studies
in dogs.
Adams et al.[94] used an HPLC method for the determination of
flurbiprofen and 40-hydroxyflurbiprofen in serum and urine. The sample
was treated with sodium chloride and sodium hydroxide. ()-2-(2-Meth-
oxybiphenyl-4-yl) propionic acid was used as internal standard. The
samples were injected on a column (30cm3.9mm) of micro Bondapak
C
18
fitted with an RP-8 guard column (3cm4.6 mm), with 0.05M potas-
sium phosphate–tetrahydrofuran (11:9) as mobile phase (1.9mL/min)
and fluorimetric detection at 320nm (excitation at 260nm). Response
was rectilinear for 50mg/mL of flurbiprofen or 40-hydroxyflurbiprofen
and 30-hydroxy-40-methoxyflurbiprofen.
160 Alaa A.-M. Abdel-Aziz et al.

Babhair [95] described an HPLC method with fluorometric detection
at 337nm (excitation at 254nm) for the determination of flurbiprofen in
dosage form urine and plasma. The method was applied on a stainless
steel column (30cm3.9 mm) of micro-Bondapak Phenyl with aq.
35% acetonitrile as mobile phase. Calibration graphs were rectilinear up
to 20mg/mL of flurbiprofen in the final test solution. Recovery from
plasma and urine was 95–98%.
Kandler and Hall [96] used an HPLC analysis of the enantiomers
of flurbiprofen and the 40-hydroxy, 30-hydroxy-40-methoxy, and 30,40-
dihydroxy metabolites in plasma and urine containing racemic isoprofen
as internal standard, and derivatized with S-a-methylbenzylamine. The
derivatives were determined by HPLC on a column (25cm4.6mm) of
Ultrasphere ODS (5mm) and Brownlee RP18 guard column. Mobile phases
(1mL/min) were aqueous 62% acetonitrile for flurbiprofen in plasma;
acetonitrile–0.05M acetic acid (11:9) for flurbiprofen and 40-hydroxyflurbi-
profen in urine; and acetonitrile:tetrahydroxyfuran:acetic acid (43:2:55) for
40-hydroxyflurbiprofen, 30-hydroxyflurbiprofen, and 40-methoxyflurbipro-
fen in plasma and urine. Flurbiprofen in plasma was detected at 254nm;
flurbiprofen in urine and 40-hydroxy, 30-hydroxy, 4-methoxy, and 30,40-
dihydroxy metabolites in plasma and urine were detected fluorimetrically.
Calibration graphs were rectilinear from 25 to 500ng/mL for the drug and
the three metabolites in plasma; 25 to 750ng/mL for the drug and its
40-hydroxy- and 30-hydroxy-4-methoxy metabolites; and 125 to 750ng/mL
for 3,4-dihydroxy metabolite in urine. Detection limits in plasma were
10ng/mL, and the coefficient of variation was 10%.
Sane et al.[97] determined flurbiprofen in tablets, using HPLC on a
column (30cm3.9 mm) of micro Bondapak C
18
with acetonitrile:water:
phosphoric acid (500:500:1) as mobile phase (1.5mL/min) and detection
at 254nm. Ketoprofen was used as internal standard. The calibration
graph was rectilinear from 0.02 to 0.08 mg/mL, and recoveries were
quantitative and the coefficient of variation was 2.5%. No interference
was observed.
Kumbhat and Mathur [98] determined flurbiprofen in aqueous humor
of human by HPLC on a column (25cm4.6 mm) of Partisil 5 ODS 3 C
18
(5mm) with a guard column, acetonitrile–0.05 M acetic acid (2:3) as
mobile phase (2mL/min) and detection at 254 nm. The retention time
for flurbiprofen was 8.3min. Calibration graphs based on peak height
were rectilinear for 50–600ng/mL of the drug, and the detection limit
was 20ng/mL.
Aboul-Enein and Bakr [99] separated flurbiprofen enantiomers in
biological fluids were derivatized by reaction with diazomethane to
form the methyl esters by HPLC in a column (25cm4.6mm) of Daicel
Chiralcel OJ (cellulose tris-(4-methylbenzoate) ester) coated on to silica
gel (10mm) with a mobile phase (1.0mL/min) of hexane:propan-2-ol (9:1)
Flurbiprofen 161

and detection at 254nm. A separation factor of 1.32 was achieved. For
urine analysis, the flurbiprofen was extracted into ethyl ether, and the
solvent was evaporated before derivatization.
Kim and Chi [100] developed an HPLC procedure with UV detection
for the quantitation of flurbiprofen released into isopropyl myristate used
as the receptor phase in an in vitro membraneless drug diffusion cell. The
drug and the internal standard, oxaprozin, were extracted from isopropyl
myristate with a mixture of dimethyl sulfoxide:methanol:water (2:1:1)
and quantitated using a reversed-phase C
18
column. The chromatograms
were completely free from interfering peak, and the relative retention
times of flurbiprofen and the internal standard were 4.9 and 6.8 min,
respectively. Calibration plots were linear over the concentration range
of 1–200mg/mL of flurbiprofen with correlation coefficient of >0.99.
Mathew et al.[101] developed a stability-indicating HPLC method for
the determination of flurbiprofen in tablets. The method is accurate,
precise, and the relative standard deviation was 0.7%. The inactive ingre-
dients present in the tablet did not interfere with Assay procedure. The
extraction procedure from the tablets was very simple. The recovery from
the synthetic mixtures was quantitative. The drug appears to be very
sensitive to strong acid and bases since a 5-min boiling caused the degra-
dation of the drug (100%) in both the solutions. Samples were mixed with
methanol for 5min and filtered. The filtrate was treated with methanolic
ibuprofen solution (internal standard, 4mg/mL) and diluted with 40%
methanol in 0.02M potassium dihydrogen phosphate aqueous buffer
before analysis by HPLC on a column (30 cm3.9mm) of C
18
with a
mobile phase (2.2mL/min) of 48% acetonitrile in 0.01 M potassium dihy-
drogen phosphate aqueous buffer and detection at 234nm. The method
was used to study the degradation of flurbiprofen.
Spraul et al.[102] identified the two major human urinary metabolites
of flurbiprofen, namely the glucuronides of flurbiprofen and 40-hydroxy-
flurbiprofen using
1
H and
19
F NMR spectroscopy. In vivo conjugation
of the racemic drug and its metabolites with D-glucuronic acid results in
diastereomeric molecules which give NMR spectra, thereby permitting
the diastereomeric proportions to be evaluated. The cause of the observed
deviation from equal proportions is discussed. This study represents the
first use of both
19
F NMR and 600MHz
1
H NMR spectroscopy coupled to
HPLC. Urine was freeze dried and reconstituted at a 10-fold increase in
concentrated 2H
2
O containing 2% acetonitrile. Portions (50 ml) of the solu-
tion were analyzed on a Spherisorb ODS-2 column (25cm4.6mm)
with gradient elution with 2H
2
O/acetonitrile/phosphate (detail given)
and detection at 254 nm. On-flow
19
F NMR and stopped-flow
1
H NMR
were used to detect any metabolites; the two major urinary metabolites,
the glucuronides of flurbiprofen and of 40-hydroxyflurbiprofen, were
identified.
162 Alaa A.-M. Abdel-Aziz et al.

Chi et al.[103] determined flurbiprofen by an HPLC analysis of flurbi-
profen in rat plasma. Plasma was vortex mixed with a methanolic solution
of oxaprozin (internal standard, 10mg/mL) and 0.1 M HCl. Flurbiprofen
was extracted into cyclohexane, and the extract was evaporated to dry-
ness under N
2
. The residue was reconstituted in the mobile phase, and the
solution was analyzed by HPLC on a column (15cm4.6mm i.d.) of
Cosmosil C
18
(5mm) with a guard column packed with pellicular C
18
(30mm), 0.02M phosphate buffer of pH 7:acetonitrile (19:6) as mobile
phase (1.2mL/min) and detection at 254nm. The calibration graph was
linear from 0.1 to 30mg/mL of flurbiprofen. Mean intraday and interday
RSD were 4.74% and 5.08%, respectively. The mean recovery was 93.1%.
The method was validated by analyses of flurbiprofen injected into rats
and sampled in blood at intervals up to 36h.
Foda and Al-Gohary [104] described that an HPLC method was used
for determination of flurbiprofen in pharmaceutical dosage forms
using a Bonda Pack C
18
column (10cm8 mm i.d.), 0.05M ammonium
acetate/acetonitrile (2:3, pH 5.2) as mobile phase (0.8 mL/min), methyl-p-
hydroxybenzoate (1mg/mL as internal standard) and detection at 247nm.
The calibration graph was linear for 0.5–9mg/mL, and the recovery and
RSD were 100.1% and 0.4%, respectively.
Deshpande et al.[105] determined flurbiprofen by an HPLC method
using fluorescence detector at 315nm (excitation at 250nm) in plasma on
5mmC
18
column (15cm4.6 mm i.d.) and acetonitrile:phosphate buffer of
pH 5.9 (68:32) as mobile phase (1.2mL/min). The internal standard
used was biphenyl benzoic acid. The calibration graph was linear from
1to24mg/mL of flurbiprofen. At the 4 mg/mL level, intraday and interday
RSD were 2.36% and 2.03%, and the corresponding values at the 8 mg/mL
were 2.13% and 3.61%. The recovery was 85.882.75%.
Park et al. [106] determined flurbiprofen in rat plasma using HPLC
with fluorescence detection. Plasma (50ml) was deproteinized by vortex-
ing and centrifuging with 125ml acetonitrile. A 10 micro l portion of the
supernatant was analyzed by HPLC on a 5 micro m C
18
column (25cm
4.6mm i.d.) with a guard column of similar material with acetonitrile:
water:phosphoric acid (1200:800:1) as mobile phase (1.5 mL/min) and
fluorescence detection at 285nm (excitation at 250 nm). The calibration
graph ranged from 0.05 to 5mg/mL with a mean recovery of 95.14%. The
mean interday RSD was 1.37%. There was no interference from endoge-
nous substances observed in any of the biological samples analyzed.
Giagoudakis and Markantonis [107] presented and validated an HPLC
method employing ultraviolet detection for the analysis of flurbiprofen
and diclofenac in a 225mL plasma sample. Chromatographic separations
were performed using a C
18
Sperisorb 5mm column (25cm4.6mm).
The mobile phase was pumped isocratically at a flow rate of 1mL/min.
The degassed mobile phase consisted of acetonitrile–0.1 M sodium acetate
Flurbiprofen 163

(35:65) adjusted to pH 6.3 with glacial acetic acid. The method is simple
with short retention time and excellent limits of detection.
Hutzler et al.[108] developed a sensitive and specific HPLC assay for
40-hydroxyflurbiprofen and flurbiprofen in human urine and plasma. No
extraction procedure was necessary for analysis of these compounds,
which reduced the time involved in sample preparation. The analytes
were separated on a Brownlee Spheri-5 C
18
column with a mobile phase of
acetonitrile: 20mM dibasic potassium phosphate buffer of pH 3 (2:3).
Fluorescence detection at 320nm (excitation at 260nm) was utilized,
providing excellent sensitivity. The limit of quantitation for 40-hydroxy-
flurbiprofen and flurbiprofen was 0.25mg/mL in urine and 0.05 and
0.25mg/mL, respectively, in plasma. Intraday, interday, freeze–thaw,
and in-process stability were tested for both compounds, and the coeffi-
cient of variation was <14% in all cases.
Tu et al.[109] determined the content of flurbiprofen and 2-(4-biphe-
nyl) propionic acid in flurbiprofen sustained release tablets by HPLC
method. The contents were determined at 247 nm for flurbiprofen and
245nm for 2-(4-biphenyl) propionic acid (a Shimpack CLS-ODS column
with methanol-aqueous phase) (60:40) as mobile phase. The average
recovery was 100.61% with relative standard deviation of 0.45% for
flurbiprofen and 100.18% with relative standard deviation of 1.75 for
2-(4-biphenyl) propionic acid. The detection limit for 2-(4-biphenyl) pro-
pionic acid was 12.5ng/mL. The method was simple, accurate, and
reproducible.
Pe
´hourcq et al.[110] developed a rapid and stereospecific HPLC
micro-method to quantify flurbiprofen enantiomers. Both flurbiprofen
enantiomers and indomethacin, used as internal standard, were extracted
with methylene chloride from 100mL of acidified plasma. The resolution
of the R- and S-forms was performed on a bonded vancomycin chiral
stationary phase (Chirobiotic V) with 20% of tetrahydrofuran in ammo-
nium nitrate (100mM, pH 5) as mobile phase. Calibration curves were
linear in the range 0.5–10mg/mL for both enantiomers. A good accuracy
was obtained for all quality controls, with intraday and interday variation
coefficients equal or less than 7.7%. Recovery of both enantiomers was
found in the range of 77.4–86.3%. The lower limit of quantitation was
0.25mg/mL for both enantiomers, without interference of endogenous
components. This validated micro-method has been successfully applied
for quantifying R- and S-flurbiprofen in rat plasma.
Ding et al.[111] determined flurbiprofen in human plasma by
reversed-phase HPLC method. The plasma concentration of flurbiprofen
was determined by HPLC at 247nm on Irregular-HC
18
column with
methanol–7.42mM phosphoric acid solution (75:25) as a mobile phase
and flow rate of 1mL/min. Samples were pretreated by solvent extrac-
tion. The linear range was 0.05–20mg/mL with detection limit of 0.2 ng.
164 Alaa A.-M. Abdel-Aziz et al.

The average recovery was 98.3%. The results showed that the method was
convenient and practicable.
Aboul-Enein and Ali [112] investigated the thermodynamic study of
the enantiomeric resolution of flurbiprofen by HPLC using Chiralpak
AD-RH column. The chiral resolution of ()-flurbiprofen was achieved
using water–acetonitrile (60:40, v/v) containing 0.1% acetic acid on a
Chiralpak AD-RH column at 20C. The enantioresolution was studied
with different percentages of acetonitrile. Thermodynamic parameters
(enthalpy, entropy, and free energy) were calculated by carrying out the
enantioresolution experiments at 0–60 C. The enantioresolution was
found to be exothermic in nature. Attempts have been made to explain
the mechanism of chiral resolution of flurbiprofen on the Chiralpak AD-
RH column.
Sajeev et al.[84] described a rapid UV spectrophotometric method and
a reversed-phase HPLC method for the determination of flurbiprofen in
bulk and in pharmaceuticals. The solvent system wavelength of detection
and chromatographic conditions were obtained in order to maximize the
sensitivity of both methods. The detection limit was 0.34mg/mL for the
UV method and 15mg/mL for the HPLC method. The methods were
employed with a high degree of precision and accuracy for the determi-
nation of total drug in two ophthalmic drop formulations of flurbiprofen.
The results of analysis were treated statistically, as USP 2000 and
International Conference of Harmonization Guidelines for validation of
analytical procedure, and by recovery studies. The results obtained in the
ultraviolet method were comparable with those obtained by using HPLC.
The column used in the liquid chromatography was a reversed-phase
4.6mm12.5 cm (5 mm) of LiChroCART Purospher end-capped C
18
LC
column. The mobile phase was methanol–acetonitrile–phosphate buffer
(pH 5.6, 40:20:40) at a flow rate of 0.75mL/min. The eluate was analyzed
at a wavelength of 248nm.
Teng et al.[113] assessed a method of analysis of flurbiprofen in
biological fluids. A simple HPLC method was developed for simulta-
neous determination of flurbiprofen enantiomers in rat serum. Serum
(0.1mL) was extracted with 2,2,4-trimethylpentane–isopropanol (95:5,
v/v) after addition of the internal standard, S-naproxen and acidification
with sulfuric acid. Separation was achieved on a Chiralpak AD-RH col-
umn with UV detection at 247nm. The calibration curve was linear rang-
ing from 0.05 to 50mg/mL for each enantiomer. The assay was applied to
the in vivo kinetic study of flurbiprofen in rats.
Paik et al.[114] performed the enantiomeric composition tests on
flurbiprofen present in patch products and in urine excretions following
patch applications as diastereomeric (R)-(þ)-1-phenylethylamides by
achiral gas chromatography and by gas chromatography-mass spectrom-
etry (GC-MS) in selected ion-monitoring mode. The method for
Flurbiprofen 165

determination of (R)- and (S)-enantiomers in the range from 0.1 to 5.0mg
was linear (r¼0.9996) with acceptable precision and accuracy. The enan-
tiomeric compositions of flurbiprofen in one patch product were identi-
fied to be racemic with relatively good precision. The urinary excretion
level of (R)-flurbiprofen was two times higher than its antipode.
Pe
´hourcq et al.[115] studied the chiral resolution of flurbiprofen enan-
tiomers by HPLC on a glycopeptide-type column chiral stationary phase.
Bonded vancomycin chiral stationary phase (chirobiotic V) was investi-
gated for the chiral liquid chromatography analysis of flurbiprofen. The
selectivity factor (a) and the chiral resolution (R
s
)ofchirobioticVwere
evaluated first as a function of the buffer pH and molarity, and second as
a function of organic modifier type and composition of the mobile phase.
Four organic modifiers, tetrahydrofuration, isopropanol, dioxane, and
methanol, have been tested for their selectivity. Optimized conditions
using 20% of tetrahydrofuran in ammonium nitrate (100mM, pH 5) were
selected for the enantioseparation of flurbiprofen from their racemic forms.
Radwan and Abnoul-Enein [116] determined the stereoselective
HPLC of flurbiprofen in rat plasma. The influence of sustained release
formulation on the pharmacokinetics of flurbiprofen enantiomers R- and
S-flurbiprofen was investigated. Therefore, a stereoselective HPLC
method was developed and validated for the rapid, quantitative determi-
nation of R- and S-flurbiprofen in rat plasma. Flurbiprofen-loaded poly(D,
L-lactide-co-glycolide) nanoparticles (rac-flurbiprofen-PLGA) were
prepared by in emulsion-solvent evaporation technique. Optimum con-
ditions for rac-flurbiprofen-PLGA nanoparticle preparation were consid-
ered, and the in vitro release of rac-flurbiprofen, R-, and S-flurbiprofen
were followed up to 48h in phosphate buffer (pH 7.4).
Charoo et al.[117] developed a simple reversed-phase HPLC method
for the determination of flurbiprofen in rat plasma, excised skin extract,
and transdermal path formulations. The mobile phase was methanol–1%
phosphoric acid in water (80:20), at a flow rate of 0.5mL/min. Ibuprofen
was used as the internal standard. Flurbiprofen and ibuprofen were
detected by UV absorption at 250 and 220nm, respectively. The limit of
quantification was 0.1mg/mL. The response was linearly dependent on
concentration in the range of 0.1–10mg/mL, and accuracy and reproduc-
ibility were good. At these concentrations, intraday and interday assay
variability was below 8%. Recovery of flurbiprofen was greater than 94%
over the linear range of calibration plot.
Lo et al.[118] developed and validated a sensitive and accurate stabil-
ity-indicating HPLC method for determining the photodegradation of
flurbiprofen with linear regression of calibration curve, intraday test,
and interday test. The relative standard deviations of intraday and inter-
day tests were lower than 1.1% and 1.7%, respectively. The percentage
recovery was between 98.2% and 102%.
166 Alaa A.-M. Abdel-Aziz et al.

Albert et al.[119] determined flurbiprofen in human serum by reversed-
phase HPLC with fluorescence detection. Flurbiprofen was extracted from
hydrochloric acid-acidified serum with pentane–ether (80:20). An octadecyl
silane column was used with a mobile phase of acetonitrile–water–
phosphoric acid (650:350:0.5). A fluorescence detector with excitation at
250nm and emission at 315nm proved a quantifiable peak for 0.1mg/mL
of flurbiprofen in 0.5mL of plasma. A comparison between UV and fluores-
cence detection systems is presented. The method is applicable to human
bioavailability and pharmacokinetic studies with flurbiprofen.
Han et al.[120] developed a method based on cloud-point extraction
for the determination of flurbiprofen in rat plasma after oral and trans-
dermal administration by HPLC coupled with ultraviolet detection. The
nonionic surfactant Genapol X-080 was chosen as the extract solvent.
Variable parameters affecting the cloud-paint extraction efficiency were
evaluated and optimized. Chromatography separation was performed on
a Diamond C
18
column (4.6mm25 cm, 10 mm) by isocratic elution with
UV detection at 254nm. The assay was linear over the range of 0.2–50 and
0.1–10mg/mL for oral and transdermal administration, respectively, and
the lower limit of quantification was 0.1mg/mL. The extraction recoveries
were more than 84.5%, the accuracies were within 3.8%, and the intra-
day and interday precisions were less than 10.1% in all cases. The method
indicated good performance in terms of reproducibility, specificity, line-
arity, precision, and accuracy and was applied to pharmacokinetic study
of the drug in rats after oral and transdermal administration.
Yang et al.[121] determined the flurbiprofen content in flurbiprofen
dry suspension by an HPLC method. The Hypersil C
18
column (25cm
4.6mm, 5mm) was used with the mobile phase of acetronitrile–0.02 mol/L
potassium dihydrogen phosphate (54:46, adjusting pH 6 with triethyla-
mine), and the detection wavelength was 254nm. The method had a good
linear relationship in the range of 2–64mg/mL (r¼0.9999). The precision of
the intraday and interday relative standard deviation was about 0.79%
and 1.04%, respectively. The average recovery rates of low, medium, and
high concentration of flurbiprofen were 99.38%, 100.05% and 99.78%,
respectively. The method is selective and accurate for the content deter-
mination of the drug in flurbiprofen dry suspension.
Liu et al.[122] established a reversed-phase HPLC method for deter-
mining the contents of flurbiprofen and preservative in flurbiprofen
ophthalmic solution and to forecast its expiration date at room tempera-
ture. The expiration date of the eye drops was delivered classical constant
temperature. The results showed that the assay was linear for flurbiprofen
within a range of 6–72mg/L and for ethyl hydroxybenzoate within a
range of 7.5–90mg/L. The mean recovery of flurbiprofen was 100%, and
relative standard deviation was 0.62%. The mean recovery of ethyl hydro-
xybenzoate was 99.9%, and relative standard deviation was 0.70%. The
Flurbiprofen 167

expiration date (t0.9) for flurbiprofen at 25C was 3.7 years, and that for
ethyl hydroxybenzoate at 25C was 1.9 years. The method is simple,
rapid, and accurate and can be used for the quality control of flurbiprofen
ophthalmic solution.
Unal et al.[123] developed and validated a bioanalytical method for
the determination of flurbiprofen from human plasma by liquid chroma-
tography with UV detection. This method is reliable and robust. The
validation results were included specificity, accuracy, extraction recov-
ery, linearity, and range. The assay can be applied to the pharmacokinetic
and bioequivalence studies. The method was carried out at room temper-
ature using a reversed-phase Nucleosil C
18
(15cm4.6 mm, 5 mm) column.
The mobile phase consists of a mixture of 0.1M sodium acetate–
acetonitrate (65:35), and the pH of the mobile phase was adjusted to 6.30
by 85% orthophosphoric acid. Flow rate of the mobile phase was 1mL/
min. The detection wavelength, 248nm, was determined by scanning the
maximum absorbance wavelength of flurbiprofen and losartan (internal
standard) in the mobile phase.
Clarcke [3] recommended the following six systems:
(1) Column: C
8
symmetry (2504.6 mm i.d., 5 mm) with symmetry C
18
precolumn (20mm).
Column temperature: 30C.
Mobile phase: (A:B) phosphate buffer (pH 3.8):acetonitrile.
Elution program: (85:15) for 6.5min to (65:35) until 25 min to (20:80)
for 30min and back to initial condition for equilibration for 7 min.
Flow rate: 1mL/min for 6.5min, then linear increase to 1.5 mL/
min for 6.5–25min and hold for 3 min (re-equilibration is made at 1.5
mL/min).
Detection: UV diode array.
Retention time: 21.3min.
(2) Column: LiChrospher 60 RP-Select B (1254mm i.d., 5mm) with
precolumn LiChrospher 60 RP-Select B (44mm i.d., 5mm).
Mobile phase: (A:B) triethylammonium phosphate buffer (25 mM,
pH 3):acetobnitrile.
Elution program: (A:B) (100:0) to (30:70) in 30min, hold for 10 min
and back to initial conditions in 3min with equilibration for 10min
before next injection.
Flow rate: 1mL/min.
Detection: UV diode array.
Standards: Nitro-n-alkanes (C
1
to C
11
)10mL in 10mL acetonitrile.
Retention index: 585 [124].
(3) Column: C
18
end-capped LiChrospher 100 RP-18e, (1254m i.d.,
5mm) with precolumn LiChrospher 124.4.
Mobile phase: Add 146mL triethylamine and about 750 mL
phosphoric acid to 530mL water. Adjust pH to 3.3 using a
168 Alaa A.-M. Abdel-Aziz et al.

10% potassium hydroxide solution and finally add 470 mL acetoni-
trile.
Flow rate: 0.6mL/min.
Detection: UV diode array.
Retention time: 11.8min.
(4) Column: ODS Sphirisorb (2004.6mm, i.d., 5mm).
Mobile phase: Acetonitrile:acetic acid (45:55) for 2 min, to (75:25) at
3%/min, hold for 6min.
Flow rate: 1.7 mL/min.
Retention time: 0.89 (relative to meclofenamic acid) [125].
(5) Column: Supelcosil LC-DP (2504.6 mm, i.d., 5 mm).
Eluent: (A:B:C) Acetonitrile:phosphoric acid (0.025%, v/v):triethy-
lamine buffer.
Isocratic elution: (25:10:5).
Flow rate: 0.6mL/min.
Detection: UV diode array (l¼229nm).
Note: The triethylamine buffer is prepared by adding 9mL con-
centrated phosphoric acid and 10mL triethylamine to 900mL water,
adjusted to pH 3.4 with dilute phosphoric acid and made up to 1L
with water.
Retention time: 8min.
(6) Column: LiChrospher 100 RP-8 (2504 mm i.d., 5mm).
Eluent: (A:B:C) Acetonitrile:phosphoric acid (0.025%):triethyla-
mine buffer.
Isocratic elution: (60:25:15).
Flow rate: 0.6mL/min.
Detection: UV diode array (l¼229nm).
8.2.4.6. Gas chromatography–mass spectrometry Paik et al.[114] per-
formed the enantiomeric composition tests on flurbiprofen present in
patch products and in urine excretions following patch applications as
diastereomeric (R)-(þ)-1-phenylethylamides by achiral gas chromatography
and GC-MS in selected ion-monitoring mode.The method for determination
of (R)- and (S)-enantiomers in the range from 0.1 to 5.0mg was linear (r¼
0.9996) with acceptable precision and accuracy. The enantiomeric composi-
tions of flurbiprofen in one patch product were identified to be racemic with
relatively good precision. The urinary excretion level of (R)-flurbiprofen was
two times higher than its antipode.
Chao et al.[126] identified flurbiprofen and its photo-products in
methanol by GC-MS. A sample of 10mM flurbiprofen in methanol (or
ethanol) was photoirradiated with sixteen 8W low-pressure quartz mer-
cury lamps, irradiated at 306nm in a Panchum PR-2000 photochemical
reactor. In total, four major photo-products derived from each sample
Flurbiprofen 169

were observed from the HPLC chromatogram. The photo-products were
separated and their structures elucidated by various spectroscopic meth-
ods. Alternatively, using GC-MS, 11 major photo-products were
observed. A reaction scheme of flurbiprofen in methanol was proposed:
the photochemical reaction routes occur mainly via esterification and
decarboxylation, followed by oxidation with singlet oxygen to produce
a ketone, alcohols, and other derivatives.
Satomoto et al [127] developed a GC-MS assay method for the quantita-
tion of flurbiprofen in human plasma. Extraction or condensing procedure
was not required and the method reduced time involved in sample prepa-
ration. The analytes were separated on the fused-silica capillary column.
The operating conditions were injector, 250C; detector, 300C; and col-
umn, 50–280C. The total gas flow rate of helium (carrier) was 50mL/min,
and the pressure of column inlet was 100–200kPa. The retention time
was 18.1min, and the limit of quantitation was 0.5mg/mL. This method
provides an easy and simple method for the detection of flurbiprofen.
Liu et al.[128] used liquid chromatography tandem/mass spectromet-
ric method for the determination of flurbiprofen in human serum. The
serum samples were precipitated with methanol. The drug was deter-
mined by the method, using electrospray ionization. Flurbiprofen and its
internal standard, indomethacin, were detected on multiple reaction
monitoring by the transitions from the precursor to the product ion
(m/z243.3/198.8 and m/z356.3/312.0). The retention times of these two
analytes were 0.9 and 1.6min, respectively. An API3000 tandem mass
spectrometer and a Shimadzu liquid chromatograph were used for all
analytes. The analytical column was a Gemini C
18
column (5cm2.1 mm,
5mm). The mobile phase, acetonitrile–water (18:82), was used at a flow
rate of 0.3mL/min. The injection volume was 3mL, and the total run time
was 3min. The calibration curve had good linearity in the range of
0.05–50mg/mL (r¼0.9995). The method was sensitive, accurate, and sim-
ple for the determination of flurbiprofen in human serum. It is suitable for
the pharmacokinetics and bioavailability study of the drug.
8.2.4.7. Capillary zone electrophoresis Zhu and Lin [129] studied the chi-
ral separation of flurbiprofen by capillary electrophoresis. The acidic chiral
drugs flurbiprofen were successfully separated into two enantiomers when
b-cyclodextrins (b-CyDs) were used as chiral selectors by capillary zone
electrophoresis, under the conditions of 0.1mol/L phosphate buffer
with pH 4.92. The comparison of four CyDs, namely b-CyD, DM-b-CyD,
HP-b-CyD, and TM-b-CyD for chiral separation was made. Flurbiprofen
can only be separated by TM-b-CyD among the CyDs. The method of chiral
separation for weak acidic compounds was also developed. The optimum
pH value for their chiral separation was about 5, close to its pK
a
value.
170 Alaa A.-M. Abdel-Aziz et al.

Hamoudova and Pospisilova [130] determined flurbiprofen in pharma-
ceuticals by capillary zone electrophoresis with spectrophotometric detec-
tion. The separation was carried out in a fused-silica capillary (60cm100m
m i.d. effective length 45cm) at 30kV with UV detection at 232nm. The
optimized background electrolyte was 20mM N-(2-acetamido)-2-
aminoethane sulfonic acid with 20mM imidazole and 10mM a-cyclodextrin
of pH 7.3. 2-Naphthoxyacetic acid was used as internal standard. A single
analysis took less than 5min. Rectilinear calibration ranges were 1–60mg/L
for flurbiprofen. The relative standard deviations values (n¼6) was 1.29%
for flurbiprofen (at 10mg/L). This validated method has been successfully
applied for the routine analysis of 10 commercially available pharmaceuti-
cal preparations (syrup, tablets, cream, and gel).
Rousseau et al.[131] reported the determination of flurbiprofen enan-
tiomers in plasma samples using a single-isomer amino cyclodextrin
derivative in nonaqueous capillary electrophoresis using 6-monodeoxy-
6-mono (3-hydroxy) propylamino-b-cyclodextrin as the chiral sector. The
nonaqueous background electrolyte was made up of 40mM ammonium
acetate in methanol, and flufenamic acid was used as internal standard.
Solid-phase extraction was used for sample cleanup prior to the nonaque-
ous capillary electrophoresis separation. The nonaqueous capillary elec-
trophoresis method reducibility was optimized by evaluating different
capillary washing sequences between runs. After having tested various
conditions, trifluoroacetic acid (1M) in methanol was finally selected. The
solid phase extraction procedure was good, reproducible analyte recov-
eries were obtained using methanol for protein denaturation, and a poly-
meric phase combining hydrophobic interactions with anion exchange
properties (Oasis MAX) was selected as extraction sorbent. The method
was validated with respect to response function, trueness, precision,
accuracy, linearity, and limit of quantification.
Sadecka et al.[132] described an isotachophoretic method for the
determination of flurbiprofen in serum. The method involved deprotoni-
zation of the biological samples with ethanol. No interference from
metabolites or other drugs was observed.
9. PHARMACODYNAMICS
The major pharmacological properties have already been reviewed in 1975
[9]. Several discriminating techniques were applied to determine the lowest
effective oral dose (mg/kg) as anti-inflammatory, analgesic, and antipyretic
drug. In the anti-inflammatory tests, three animal species were used: guinea
pig, rat, and mouse [21,22,133]. In the guinea pig, the UV-erythema test was
employed in which the reference compound (aspirin, 80mg/kg) was found
to correspond to 0.25mg/kg of flurbiprofen. In the mouse model, the
Flurbiprofen 171

capillary permeability of the peritoneum was evaluated by use of a dye
(Pontamine sky blue). Aspirin at 120mg/kg was equivalent to 0.47mg/kg
of flurbiprofen. In the rat, three methods were employed: the carrageenan
edema test, and two adjuvant arthritis models for the developing state and
the established state. Reference compounds were, respectively, aspirin (81
mg/kg) in the first and indomethacin (1mg/kg) and phenylbutazone (10
mg/kg) in the two latter models. The corresponding lowest effective dose
for flurbiprofen was 0.11 and 0.33mg/kg in the two latter models. With the
carrageenan edema test, a subgroup of rats was also tested that were
bilaterally adrenalectomized to rule out any adrenocortical interference.
Several conclusions were drawn from this study. Flurbiprofen was devoid
of adrenocortical stimulating properties and was one of the most potent
agents of this type reported yet, at least 10 times more potent than ibupro-
fen. It was postulated that the mode of action in the mouse and rat was not
identical to that of aspirin. In US patent 3,755,427 (August 28, 1973) [134],it
was stated that flurbiprofen was between 75 and over 100 times as potent as
aspirin. It was reported that the relative potency of various hydratropic
acids were tested for their relaxing ability on guinea pig tracheal ring
contraction after sensitization by rat SRS-A [22]. Furthermore, the paper
provided information not only for flurbiprofen but also for the levorotary
()- and dextrorotary (þ)-enantiomers. It became apparent that the relaxing
potency of the racemic mixture () was unexpectedly too low as compared
to the dextrorotary component, suggesting that the dextrorotary component
was hindered by the simultaneous presence of the levorotary component.
The putative interaction between the two enantiomers was tested by the
simultaneous addition of the two separate enantiomers to the muscle bath.
Reversal by the dextrorotary component was diminished by the simulta-
neous presence of the () flurbiprofen. Taking this into consideration (þ),
flurbiprofen was approximately 80-fold more potent than () flurbiprofen.
10. PHARMACOKINETICS
Pharmacokinetic properties have been assessed in different species [135].
In human, when assessed by HPLC of the racemic molecule, a two-
compartment open model appeared the most appropriate for flurbiprofen
[136]. Drug absorption efficiency was found independent of the oral dose.
The intact drug resides mainly in the peripheral and central compart-
ments, disappearing with a terminal half-life of approximately 5.5 h. More
than 99% of flurbiprofen is bound to serum proteins. The serum flurbi-
profen concentrations in clinical use, however, show occupancy of less
than 10% of the primary binding sites. Drug interactions will therefore not
automatically occur with simultaneous use.
172 Alaa A.-M. Abdel-Aziz et al.

10.1. Metabolic pathway in human
Oxidation and conjugation are the main pathways of metabolism in
human. More than 95% of an oral dose is excreted via the kidney within
24h. In all, 40–47% of a daily oral dose is excreted as 2-[2-fluoro-40-
hydroxy-4-biphenylyl]propionic acid, 5% as 2-[2-fluoro-30,40-hydroxy-4-
biphenylyl]propionic acid, 20–30% as 2-[2-fluoro-30-hydroxy-40-methoxy-
4-biphenylyl]propionic acid, and 20–25% as the parent molecule
flurbiprofen. Between 65% and 85% of flurbiprofen and its metabolites
are present as glucuronide and sulfate conjugates. Stereoselective HPLC
of human plasma has also been performed [137]. After oral administra-
tion of 25mg of the R()-enantiomer of flurbiprofen, no indication was
found that inversion to the S(þ)-enantiomer occurred. This was confirmed
in healthy volunteers taking either 50mg R-() flurbiprofen or S(þ)
flurbiprofen [138].
Stereoselective studies have been performed following the disposition
of flurbiprofen in normal volunteers after a single 50 mg racemic dose
[139], in healthy female subjects following oral administration of the
single enantiomers of flurbiprofen, 50mg S(þ)- or R() flurbiprofen or
100mg R() flurbiprofen or placebo, in a four-way crossover design with
placebo [140], in patients with end-stage renal disease undergoing con-
tinuous ambulatory peritoneal dialysis (CAPD) after administration of a
single 100mg racemic dose [141], and stereoselective disposition of race-
mic flurbiprofen in single and multiple dosing in uraemic patients [142].
In patients with liver disease with ascites and in renal failure patients with
a creatinine clearance of less than 10mL/min, significant higher free
fractions of R()- and S(þ)-flurbiprofen were detected in conjunction
with lower albumin concentrations [143].
An overview of the clinical pharmacokinetics of flurbiprofen and its
enantiomers is presented in Ref. [144]. In a review [145] on the binding of
flurbiprofen to albumin in human plasma, it was reported that at low
therapeutic concentrations, the S(þ)-enantiomer has a higher protein
binding than its R() antipode. At high drug concentrations, there is no
measurable difference, however. In an ultrafiltration study done with
normal volunteers, the free fraction of R() flurbiprofen was higher
than its S(þ) antipode at lower drug levels but similar for both enantio-
mers at higher drug levels. Patients with renal impairment and patients
exhibiting hypoalbuminemia have higher free fractions of flurbiprofen
enantiomers than normal volunteers. Plasma protein binding of an enan-
tiomer is not influenced by its own concentration or the presence of
its antipode under clinical therapeutic conditions [146]. As mentioned
above, the main routes of biotransformation of flurbiprofen are through
oxidation and conjugation. Oxidation has been investigated more specifi-
cally [147] for the enantiomers of flurbiprofen utilizing human liver
Flurbiprofen 173

microsomes. The most prominent oxidative metabolism route is by cyto-
chrome P450. It was established that cytochrome P450 2C9 and its allelic
variant R144C catalyzed the oxidative reaction. Interestingly, there was
no stereoselective preference of one enantiomer over the other. Safety for
intestinal permeability changes when using the racemate or the separate
enantiomers of flurbiprofen was studied in rats, for which species, it was
established that only a minimal inversion of the R()-enantiomer
takes place. Intestinal permeability was measured by urinary excretion
of
51
Cr–EDTA [148].
It was established that at both dosages used (1 and 3mg/kg for the
racemic drug and half for the enantiomers), permeability was signifi-
cantly different from control. R() flurbiprofen was safest in both dos-
age ranges. S(þ) flurbiprofen inflicted similar damage as the racemic
form. It was shown [149] that in rats R() flurbiprofen gave the same
increase of intestinal permeability, but the difference was that the
impact on mucosal prostanoid production was smaller and not accom-
panied by ulcerative changes in the small intestine. Although it would
seem attractive to develop therapeutic R()-enantiomers of 2-arylproio-
nic acids due to its supposedly lower toxicological profile, it must be
borne in mind that the presumed pharmacological action required for
reducing inflammation is inhibition of prostaglandin synthesis. This
property resides primarily, in the case of flurbiprofen, in the S(þ)-
enantiomer for which a difference of 30–100 times compared to the R
()-enantiomer was established depending on the model used. Only
with full metabolic inversion of a R()- to a S(þ)-enantiomer would
such a therapeutic drug be a possibility. For flurbiprofen, this is not the
case in humans [150–152].
10.2. Elimination profile in equine urine
Flurbiprofen and its main acidic metabolites were detected in equine
urine after a single-dose administration of 500 mg flurbiprofen to two
2.5- to 3.5-years-old mares, in order to be used in equine doping
control routine analysis. The urine levels of the parent drug were deter-
mined using GC/MS. Five acidic metabolites were found in the urine
(Fig. 4.17). The structure of the proposed metabolites was confirmed by
HRMS accurate mass measurements (Fig. 4.18 and Table 4.5). The highest
flurbiprofen concentration was 204mg/mL at 1- to 3-h post administra-
tion. Flurbiprofen could be detected for 24–37h in urine using the stan-
dard screening procedure. All metabolites were present 25-h post
administration, while 40-hydroxyflurbiprofen could be traced for more
than 48h, and it is regarded as the long-term metabolite of flurbiprofen in
horse [153].
174 Alaa A.-M. Abdel-Aziz et al.

HO
H
3
CO
HO
CH
F
4⬘-Hydroxyflurbiprofen
2
CH
3
COOH
HO
CH
F
X⬘-Hydroxyflurbiprofen
5
CH
3
COOH
CH
F
Flurbiprofen
1
CH
3
COOH
CH
F
3⬘,4⬘-Dihydroxy flurbiprofen
3
CH
3
COOH
HO
HO
CH
F
X⬘-hydroxy-y⬘-methoxy-flurbiprofen
6
CH
3
COOH
CH
F
3⬘-Hydroxy-4⬘-methoxy-flurbiprofen
4
CH
3
COOH
H
3
CO
HO
FIGURE 4.17 The chemical structures of flurbiprofen and its five metabolites [135].
TABLE 4.5 Calculated data of the exact mass measurements of the flurbiprofen and its
metabolites (I–V)[153]
Compound Calculated mass Real mass Dm/m(ppm)
a
Flurbiprofen (I) 316.1271 316.1296 7.9
301.1039 301.1061 7.3
40-OH-flurbiprofen (II) 404.1633 404.1640 1.7
389.1426 389.1405 5.4
30-40-diOH-flurbiprofen (III) 492.2090 492.1985 21.3
477.1755 477.1750 1.0
30OH-40-MeO-flurbiprofen (IV) 434.1769 434.1746 5.3
419.1459 419.1511 12.4
x0-OH-flurbiprofen (V) 404.1635 404.1640 1.2
389.1382 389.1405 5.9
a
Dm/m¼(real masscalculated mass/real mass)10
6
[153].
Flurbiprofen 175

m/z->
m/z->
A
bundance
m/z->Abundance
Abundance
0
200,000
400,000
600,000
800,000
1,000,000
1,200,000
1,400,000
1,600,000
1,800,000
2,000,000
2,200,000
2,400,000
2,600,000
2,800,000
3,000,000
3,200,000
73
73
73
73
77
77
131
117 133 152
165 180
198 316
301
147 165 196
253
268
287
389
404
95 147 179 202 253
Scan 469 (8,553 min): IR05,D
Scan 484 (8,731 min): IR05,D
Scan 408 (7,828 min): IR05,D
Scan 220 (5,603 min): IR05,D
287 375 460 477
492
267
55
91 131147
229
Full mass scan of 3⬘-MeOH,4⬘-OH-Flurbiprofen-bisTMS (IV)
Full mass scan of 3⬘,4⬘-diOH-Flurbiprofen-trisTMS (III)
Full mass scan of 4⬘-OH-Flurbiprofen-bisTMS (II)
Full mass scan of Flurbiprofen-TMS (I)
267 287 317 341 375 404 419 434
M
+
-COOTMS
M
+
-COOTMS
M
+
-COOTMS
M
+
-COOTMS
M
+
-CH
3
M
+
-CH
3
M
+
-CH
3
M
+
M
+
M
+
M
+
-(COOTMS, OTMS, F)
M
+
-(COOTMS, F, CH
3
)
M
+
-(COOTMS, F, CH
3
)
M
+
-(COOTMS, F)
M
+
-(COOTMS, F)
M
+
-2CH
3
M
+
-CH
3
M
+
M
+
-COOTMS, OCH
3
, F
20,000
0
0
0
100,000
300,000
500,000
700,000
900,000
1,100,000
1,300,000
1,500,000
1,700,000
1,900,000
2,100,000
2,300,000
2,600,000
2,800,000
100,000
200,000
300,000
400,000
500,000
600,000
700,000
800,000
900,000
1,000,000
40,000
60,000
80,000
100,000
120,000
140,000
160,000
180,000
200,000
220,000
240,000
260,000
280,000
FIGURE 4.18 Mass spectrum and fragmentation pattern of TMS derivatives of flurbi-
profen (I) and flurbiprofen metabolites (II–VI) in urine samples taken from a Skyrian mare
5h after oral administration of 500mg flurbiprofen. The sample had been prepared
according to the screening procedure for NSAIDs [153].
176 Alaa A.-M. Abdel-Aziz et al.

ACKNOWLEDGMENTS
The authors wish to thank Mr. Tanvir A. Butt, Pharmaceutical Chemistry Department, College
of Pharmacy, King Saud University for his secretarial assistance in preparing this chapter.
REFERENCES
[1] 14th ed., Maryadele J. O’Neil (Ed.), The Merck Index, an Encyclopedia of Chemicals,
Drugs and Biologicals, Merck Research Laboratories Division of Merck Co., Inc.,
Whitehouse Station, NJ, 2006.
[2] 13th ed., S. Budavari (Ed.), The Merck Index, Merck & Co., Inc, Rahway, NJ, 2001.
[3] Anthony C. Moffat, M. David Osselton, Brian Widdop, third ed., Clarcke’s Analysis of
Drugs and Poisons in Pharmaceuticals, Body Fluids and Postmortem Materials, vol. 2,
Pharmaceutical Press, London, UK, 2004 1056.
[4] K. Uekama, T. Imai, F. Hirayama, M. Otagiri, K. Harata, Chem. Pharm. Bull. 32 (1984)
1662–1664.
[5] P. Camps, S. Gime
´nez, Tetrahedron Asymm. 6 (1995) 991–1000.
[6] R. Morrone, G. Nicolosi, A. Patti, M. Piattelli, Tetrahedron Asymm. 6 (1995) 1773–1778.
[7] P. Spizzo, A. Basso, C. Ebert, L. Gardossi, V. Ferrario, D. Romano, F. Molinari, Tetra-
hedron 63 (2007) 11005–11010.
[8] S. Gro
¨sch, K. Schilling, A. Janssen, T.J. Maier, E. Niederberger, G. Geisslinger, Bio-
chem. Pharmacol. 69 (2005) 831–839.
[9] S.S. Adams, K.F. McCullough, J.S. Nicholson, Arzneim. Forsch. 25 (1975) 1786–1791.
[10] Analgesic and anti-inflammatory agents, 29th ed., J.E.F. Reynolds (Ed.), Martindale:
The Extra Pharmacopeia, The Pharmaceutical Press, London, UK, 1989, pp. 1–46.
[11] R.N. Sud, R.S. Greval, R.S. Bajwa, Indian J. Med. Sci. 49 (1995) 205–209.
[12] M. Diestelhorst, B. Schmidt, W. Konen, U. Mester, P.S. Raj, J. Cataract Refract. Surg.
22 (Suppl. 1) (1996) 788–793.
[13] R.B. Vajpayee, B.P. Dhakal, S.K. Gupta, M.S. Sachdev, G. Satpathy, S.G. Honavar,
A. Panda, Aust. N. Z. J. Ophthalmol. 24 (1996) 131–135.
[14] A. Appiotti, L. Gualdi, M. Alberti, M. Gualdi, Clin. Ther. 20 (1998) 913–920.
[15] D.S. Jones, C.R. Irwin, A.D. Woolfson, J. Djokic, V. Adams, Pharm. Sci. 88 (1999)
592–598.
[16] M. Hofer, M. Pospisil, I. Pipalova, Folia Biol. 42 (1996) 267–269.
[17] J.D. McCracken, W.J. Wechter, Y. Liu, R.L. Chase, D. Kantoci, E.D. Murray Jr., D.
D. Quiggle, Y. Mineyama, J. Clin. Pharmacol. 36 (1996) 540–545.
[18] L. Juchelkova, M. Hofer, M. Pospisil, I. Pipalova, Physiol. Res. 47 (1998) 73–80.
[19] S.M. Soulier, J.C. Page, L.C. Larsen, B.C. Grose, J. Foot Ankle Surg. 36 (1997) 414–417
discussion 446.
[20] U. Bragger, T. Muhle, I. Fourmousis, N.P. Lang, A. Mombelli, J. Periodontal Res.
32 (1997) 575–582.
[21] M.L. Brochier, Eur. Heart J. 14 (1993) 951–957.
[22] M.E. Greig, R.L. Griffin, J. Med. Chem. 18 (1975) 112–116.
[23] J. Lotsch, G. Geisslinger, P. Mohammadian, K. Brune, G. Kobal, Br. J. Clin. Pharmacol.
40 (1995) 339–346.
[24] N.M. Davies, Clin. Pharmacokinet. 28 (1995) 100–114.
[25] G. Geisslinger, S.H. Ferreira, S. Menzel, D. Schlott, K. Brune, Life Sci. 54 (1994)
PL173–PL177.
[26] W.J. Wechter, J. Clin. Pharmacol. 34 (1994) 1036–1042.
[27] D. Picot, P.J. Loll, R.M. Garavito, Nature 367 (1994) 243–249.
[28] R. Garg, A. Kurup, S.B. Mekapati, C. Hansch, Chem. Rev. 103 (2003) 703–732.
Flurbiprofen 177

[29] A.S. Michaelidou, D. Hadjipavlou-Litina, Chem. Rev. 105 (2005) 3235–3271.
[30] J.R. Vane, R.M. Botting, Inflamm. Res. 44 (1995) 1–10.
[31] W.L. Smith, R.M. Garavito, D.L. DeWitt, J. Biol. Chem. 271 (1996) 33157–33160.
[32] B. Cryer, M. Feldman, Am. J. Med. 104 (1998) 413–421.
[33] B.M. Peskar, S. Kluge, B.A. Peskar, S.M. Soglowek, K. Brune, Prostaglandins 42 (1991)
515–531.
[34] N. Kawai, N. Kato, Y. Hamada, T. Shioiri, Chem. Pharm. Bull. 31 (1983) 3139–3148.
[35] D.D. Leipold, D. Kantoci, E.D. Murray Jr., D.D. Quiggle, W.J. Wechter, Chirality
16 (2004) 379–387.
[36] W.J. Wechter, D.D. Leipold, E.D. Murray Jr., D.D. Quiggle, J.D. McCracken, R.
S. Barrios, N.M. Greenberg, Cancer Res. 60 (2000) 2203–2208.
[37] J.L. Eriksen, S.A. Sagi, T.E. Smith, S. Weggen, P. Das, D.C. McLendon, V.V. Ozols,
K.W. Jessing, K.H. Zavitz, E.H. Koo, T.E. Golde, J. Clin. Invest. 112 (2003) 440–449.
[38] G.K. Wilcock, Alzheimers Dement. 2 (2006) 150–152.
[39] L. Gasparini, E. Ongini, D. Wilcock, D. Morgan, Brain Res. Rev. 48 (2005) 400–408.
[40] R.C. Griesbach, D.P.G. Hamon, R.J. Kennedy, Tetrahedron Asymm. 8 (1997) 507–510.
[41] D.P.G. Hamon, R.A. Massy-Westropp, J.L. Newton, Tetrahedron 51 (1995)
12645–12660.
[42] B.J. Armitage, J. S. Nicholson, US Patent 4,036,989..
[43] W. Engel, E. Seeger, H. Teufel, G. Engelhardt, US Patent 3,859,338..
[44] S.S. Adams, B.J. Armitage, J.S. Nicholson, A. Ribera Blancafort, US Patent 4,053,639..
[45] S.C. Stinson, Chem. Eng. News 9 (1995) 44–72.
[46] T.Z. Wang, E. Pinard, L.A. Paquette, J. Am. Chem. Soc. 118 (1996) 1309–1318.
[47] N.M. Davies, J. Chromatogr. B Biomed. Sci. Appl. 691 (1997) 229–261.
[48] S. Beilles, P. Cardinael, E. Ndzie, S. Petit, G. Coquerel, Chem. Eng. Sci. 56 (2001)
2281–2294.
[49] Q.M. Gu, C.S. Chen, C.J. Sih, Tetrahedron Lett. 27 (1986) 1763–1766.
[50] W. Rhys-Williams, F. McCarthy, J. Baker, Y.F. Hung, M.J. Thomason, A.W. Lloyd, G.
W. Hanlon, Enzyme Microb. Technol. 22 (1998) 281–287.
[51] H.-A. Bae, K.-W. Lee, Y.-H. Lee, J. Mol. Catal. B Enzym. 40 (2006) 24–29.
[52] E.G. Lee, H.S. Won, H.-S. Ro, Y.-W. Ryu, B.H. Chung, J. Mol. Catal. B Enzym. 26 (2003)
149–156.
[53] J.Y. Wu, S.W. Liu, Enzyme Microb. Technol. 26 (2000) 124–130.
[54] J.D. Stewart, Curr. Opin. Chem. Biol. 5 (2001) 120–129.
[55] S.H. Wu, Z.W. Guo, C.J. Sih, J. Am. Chem. Soc. 112 (1990) 1990–1995.
[56] G. Duan, C.B. Ching, Biochem. Eng. J. 2 (1998) 237–245.
[57] H.Y. Zhang, X. Wang, C.B. Ching, J.C. Wu, Biotechnol. Appl. Biochem. 42 (2005) 67–71.
[58] R. Gandolfi, R. Gualandris, C. Zanchi, F. Molinari, Tetrahedron Asymm. 12 (2001)
501–504.
[59] A. Romano, R. Gandolfi, F. Molinari, A. Converti, M. Zilli, M.D. Borghi, Enzyme
Microb. Technol. 36 (2005) 432–438.
[60] F. Molinari, R. Gandolfi, A. Converti, M. Zilli, Enzyme Microb. Technol. 27 (2000)
626–630.
[61] R. Gandolfi, A. Converti, D. Pirozzi, F. Molinari, J. Biotechnol. 92 (2001) 21–26.
[62] P. Thorpe, J. Castar, Drugs Fut. 1 (1976) 323 US Patent 3755427.
[63] M. Schlosser, H. Geneste, Chem. Eur. J. 4 (1989) 1969–1973.
[64] G. Lu, R. Franzen, X.J. Yu, Y.J. Xu, Chin. Chem. Lett. 17 (2006) 461–464.
[65] Y. Terao, Y. Ijima, H. Kakidani, H. Ohta, Bull. Chem. Soc. Jpn. 76 (2003) 2395–2397.
[66] 16th ed., British Pharmacopoeia, vol. 1, Her Majesty Stationary Office Publication, Ltd.,
London, 2000 Online, CD.
[67] I. Kumar, K. Manju, R.S. Jolly, Tetrahedron Asymm. 12 (2001) 1431–1434.
[68] G. Mollica, M. Geppi, R. Pignatello, C.A. Veracini, Pharm. Res. 23 (2006) 2129–2140.
178 Alaa A.-M. Abdel-Aziz et al.

[69] G. Metz, X.L. Wu, S.O. Smith, J. Magn. Reson. 110 (1994) 219–227.
[70] B.M. Fung, A.K. Khitrin, K. Ermolaev, J. Magn. Reson. 142 (2000) 97–101.
[71] R. Kitamaru, F. Horii, K. Murayama, Macromolecules 19 (1986) 636–643.
[72] J.G. Powles, J.H. Strange, Proc. Phys. Soc. 82 (1963) 6–15.
[73] M. Geppi, S. Guccione, G. Mollica, R. Pignatello, C.A. Veracini, Pharm. Res. 22 (2005)
1544–1555.
[74] R. Pignatello, M. Ferro, G. Puglisi, AAPS PharmSciTech 3 (2002) 35–45.
[75] D.L. VanderHart, W.L. Earl, A.N. Garroway, J. Magn. Reson. 44 (1981) 361–401.
[76] P. Hodgkinson, Prog. Nucl. Magn. Reson. Spectrosc. 46 (2005) 197–222.
[77] G. Antonioli, P. Hodgkinson, J. Magn. Reson. 168 (2004) 124–131.
[78] J.L. Flippen, R.D. Gilardi, Acta Cryst. B31 (1975) 926–928.
[79] J.R. Yates, S.E. Dobbins, C.J. Pickard, F. Mauri, P.Y. Ghi, R.K. Harris, Phys. Chem.
Chem. Phys. 7 (2005) 1402–1407.
[80] C.H. Schwalbe, S.J. Teat, S.E. David, W.J. Irwin, B.R. Conway, P. Timmins, Acta Cryst.
A61 (2005) C350.
[81] B.D. Anderson, R.A. Conradi, J. Pharm. Sci. 74 (1985) 815.
[82] United States Pharmacopoeia, USP 24-NF 19 through supplement 3, 24th ed., United
States Pharmaceutical Convention, Inc, Rockville, MD, 2001 pp. 2214–2216.
[83] R.I. El-Bagary, Bull. Facul. Pharm. Cairo University, 38 (2000) 67–73 .
[84] C. Sajeev, P.R. Jadhav, D. Ravishankar, R.N. Saha, Anal. Chim. Acta 463 (2002)
207–217.
[85] C.S. Chauthan, I. Singhvi, P.K. Choudhury, Asian J. Chem. 19 (2007) 3286–3288.
[86] M.M. Baraka, M.M. El-Henawee, H.M. Khalil, Zagazig J. Pharm. Sci. 5 (1996) 138–142.
[87] X.X. Wang, G. Aodeng, A. Juan, Neimenggu Daxue Xuebao, Ziran Kexueban 40 (2009)
431–434.
[88] A.A. Bunaciu, C. Petrisor, H.Y. Aboul-Enein, Instrum. Sci. Technol. 26 (1998) 353–362.
[89] A.A. Bunaciu, A. Grasu, H.Y. Aboul-Enein, Anal. Chim. Acta 311 (1995) 193–197.
[90] V.V. Dhavse, D.V. Parmar, P.V. Devarajan, J. Chromatogr. B 694 (1997) 449–453.
[91] M.I.R.M. Santoro, A.K. Singh, E.R.M. Kedor-Hackmann, J. Liq. Chromatogr. Relat.
Technol. 26 (2003) 517–527.
[92] G. Zhang, Y. Chai, S. Ji, Y. Zhong, X. Ying, J. Li, Y. Wu, Acad. J. Sec. Mil. Med. Univ.
Shanghai 20 (10) (1999).
[93] B.G. Snider, L.J. Beaubien, D.J. Sears, P.D. Rahn, J. Pharm. Sci. 70 (1981) 1347–1349.
[94] W.J. Adams, B.E. Bothwell, W.M. Bothwell, G.J. VanGiessen, D.G. Kaiser, Anal. Chem.
59 (1987) 1504–1509.
[95] S.A. Babhair, J. Liq. Chromatogr. Relat. Technol. 11 (1988) 463–473.
[96] M.P. Knadler, S.D. Hall, J. Chromatogr. Biomed. Appl. 494 (1989) 173–182.
[97] R.T. Sane, S.M. Purandare, V.G. Nayak, M.D. Joshi, S.N. Dhumal, P.S. Mainkar,
V.R. Nerukar, V.R. Bhate, Indian Drugs 26 (1989) 503–505.
[98] S. Kumbhat, N.K. Mathur, Anal. Lett. 23 (1990) 627–634.
[99] H.Y. Aboul-Enein, S.A. Bakr, J. Liq. Chromatogr. 15 (1992) 1983–1992.
[100] H. Kim, S.C. Chi, Yakche Hakhoechi 22 (1992) 63–68.
[101] M. Mathew, V. Das Gupta, C. Bethea, Drug Dev. Ind. Pharm. 19 (1993) 493–498.
[102] M. Spraul, M. Hofmann, I.D. Wilson, E. Lenz, J.K. Nicholson, J.C. Lindon, J. Pharm.
Biomed. Anal. 11 (1993) 1009–1015.
[103] S.C. Chi, H. Kim, S.C. Lee, Anal. Lett. 27 (1994) 377–389.
[104] N.H. Foda, O.M. Al-Gohary, Anal. Lett. 27 (1994) 2523–2534.
[105] S.G. Deshpande, K.K. Singh, M.R. Baichwal, Indian Drugs 32 (1995) 227–229.
[106] K.M. Park, Z.G. Gao, C.K. Kim, J. Liq. Chromatogr. Relat. Technol. 20 (1997) 1849–1855.
[107] G. Giagoudakis, S.L. Markantonis, J. Pharm. Biomed. Anal. 17 (1998) 897–901.
[108] J.M. Hutzler, R.F. Frye, T.S. Tracy, J. Chromatogr. B 749 (2000) 119–125.
[109] L. Tu, W. Weng, H. Xu, Fudan Xuebao, Yixue Kexueban 28 (2001) 78–79.
Flurbiprofen 179

[110] F. Pe
´hourcq, M. Matoga, C. Jarry, B. Bannwarth, Biomed. Chromatogr. 18 (2004)
330–334.
[111] X. Ding, S. Wang, Y. Zhang, S. Gao, Zhongguo Yiyuan Yaoxue Zazhi 21 (2001) 472–473.
[112] H.Y. Aboul-Enein, I. Ali, Pharmazie 57 (2002) 682–685.
[113] X.W. Teng, S.W.J. Wang, N.M. Davies, J. Pharm. Biomed. Anal. 33 (2003) 95–100.
[114] M.J. Paik, D.T. Nguyen, K.R. Kim, Arch. Pharm. Res. 27 (2004) 1295–1301.
[115] F. Pe
´hourcq, C. Jarry, B. Bannwarth, Biomed. Chromatogr. 15 (2001) 217–222.
[116] M.A. Radwan, H.Y. Aboul-Enein, Chirality 16 (2004) 119–125.
[117] N.A. Charoo, A.A.A. Shamsher, K. Kohli, K.K. Pillai, Z. Rahman, Chromatographia
62 (2005) 493–497.
[118] C. Lo, Y. Liou, Y. You, A. Wu, Fenxi Huaxue 34 (2006) 1327–1330.
[119] K.S. Albert, W.R. Gillespie, A. Raabe, M. Garry, J. Pharm. Sci. 73 (1984) 1823–1825.
[120] F. Han, R. Yin, X.L. Shi, Q.A. Jia, H.Z. Liu, H.M. Yao, L. Xu, S.M. Li, J. Chromatogr. B
868 (2008) 64–69.
[121] M. Yang, J. Huang, X. Lei, X. Zhong, Zhongguo Yaoye 17 (2008) 15–16.
[122] A.W. Liu, J. Li, Y. Sang, S. Xu, S. Xu, Z. He, Shenyang yaoke Daxue Xuebao 25 (2008)
800–805.
[123] B.O. Unal, S. Guler, D.D. Erol, Hacettep Univ. J. Facul. Pharm. 29 (2009) 25–35.
[124] J. Hartstra, J.P. Franke, R.A. de Zeeuw, through ref. 3, vol. 1, p. 517.
[125] E.M. Koves, J. Chromatogr. 692 (1995) 103–119.
[126] S.H. Chao, H.T. Ho, F.A. Chen, P.Y. Lin, Y.C. Yu, A.B. Wu, Biomed. Chromatogr.
21 (2007) 527–533.
[127] M. Satomoto, Y. Adachi, H. Higuchi, K. Watanabe, T. Satoh, Masui 51 (2002) 431–434.
[128] Y. Liu, G. Liu, Y. Liu, S. Li, J. Jia, C. Yu, Yaowu Fenxi Zazhi 28 (2008) 1248–1251.
[129] X.F. Zhu, B.C. Lin, SePu 18 (2000) 70–72.
[130] R. Hamoudova, M. Pospisilova, J. Pharm. Biomed. Anal. 41 (2006) 1463–1467.
[131] A. Rousseau, M. Pedrini, P. Chiap, R. Ivanyi, J. Crommen, M.F. Jacques, A.C. Servais,
Electrophoresis 29 (2008) 3641–3648.
[132] J. Sadecka, A. Hercegova, J. Polonsky, Pharmazie 55 (2000) 859–860.
[133] E.E. Nishizawa, D.J. Wynalda, D.E. Suydam, B.A. Molony, Thromb. Res. 3 (1973)
577–588.
[134] S.S. Adams, J.B. Armitage, J.S. Nicolson, US Patent 3,755,427, 1973..
[135] P.C. Risdall, S.S. Adams, E.L. Crampton, B. Marchant, Xenobiotica 8 (1978) 691–703.
[136] D.G. Kaiser, C.D. Brooks, P.L. Lomen, Am. J. Med. 80 (1986) 10–15.
[137] F. Jamali, B.W. Berry, M.R. Tehrani, A.S. Russell, J. Pharm. Sci. 77 (1988) 666–669.
[138] G. Geisslinger, S. Menzel-Soglowek, J. Chromatogr. Biomed. Appl. 573 (1992) 163–167.
[139] M.P. Knadler, D.C. Brater, S.D.S. Hall, Br. J. Clin. Pharmacol. 33 (1992) 369–375.
[140] G. Geisslinger, J. Lotsch, S. Menzel, G. Kobal, K. Brune, Br. J. Clin. Pharmacol. 37 (1994)
392–394.
[141] E.A. Cefali, W.J. Poynor, D. Sica, S. Cox, J. Clin. Pharmacol. 31 (1991) 808–814.
[142] M.P. Knadler, D.C. Brater, S.D. Hall, Br. J. Clin. Pharmacol. 33 (1992) 377–383.
[143] R. Blouin, I. Chaudhary, K. Nishihara, S. Cox, Br. J. Clin. Pharmacol. 35 (1993) 62–64.
[144] N.M. Davies, Clin. Pharmacokinet. 28 (1995) 100–114.
[145] F. Lapicque, N. Muller, E. Payan, N. Dubois, P. Netter, Clin. Pharmacokinet. 25 (1993)
115–123.
[146] M.P. Knadler, D.C. Brater, S.D. Hall, J. Pharmacol. Exp. Ther. 249 (1989) 378–385.
[147] T.S. Tracy, B.W. Rosenbluth, S.A. Wrighton, F.J. Gonzalez, K.R. Korzekwa, Biochem.
Pharmacol. 49 (1995) 1269–1275.
[148] N.M. Davies, M.R. Wright, A.S. Russell, F. Jamali, J. Pharm. Sci. 85 (1996) 1170–1173.
[149] T. Mahmud, S. Somasundaram, G. Sigthorsson, R.J. Simpson, S. Rafi, R. Foster, I.
A. Tavares, A. Roseth, A.J. Hutt, M. Jacob, J. Pacy, D.L. Scott, J.M. Wrigglesworth,
I. Bjarnason, Gut 43 (1998) 775–782.
180 Alaa A.-M. Abdel-Aziz et al.

[150] M.R. Wright, N.M. Davies, F. Jamali, J. Pharm. Sci. 83 (1994) 911–912.
[151] S. Menzel-Soglowek, G. Geisslinger, W.S. Beck, K. Brune, J. Pharm. Sci. 81 (1992)
888–891.
[152] G. Geisslinger, S. Menzel-Soglowek, W.S. Beck, K. Brune, Agents Actions Suppl.
44 (1993) 31–36.
[153] C. Tsitsimpikou, M.-H.E. Spyridaki, I. Georgoulakis, D. Kouretas, M. Konstantinidou,
C.G. Georgakopoulos, Talanta 55 (2001) 1173–1180.
Flurbiprofen 181