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Ranitidine hydrogel/Asian Journal of Pharmaceutical Sciences 2011, 6 (5): 191-201
In vitro/in vivo study for controlled release of ranitidine
hydrochloride from polymeric blend hydrogel
Ganesan Poovi, Acharya Ramsai Karri, Hanuma Nayak Sriramamurthy, Magharla Dasaratha Dhanaraju
*
GIET School of Pharmacy, NH-5, Chaitanya Nagar, Rajahmundry, India
Received 1 April 2011; Revised 22 June 2011; Accepted 4 September 2011
_____________________________________________________________________________________________________________
Abstract
The objective of this study was to prepare and evaluate ranitidine hydrochloride immobilized polymer blend hydrogels. Three types
of blend hydrogels were prepared with three different ratios (5:1, 4:2, 3:3) by physically blending two different natural polymers and
a model drug, ranitidine hydrochloride, was immobilized into these hydrogels for the studies of blending effect, drug release, swelling
study and in-vivo study. The blending effect of gelatin with a polysaccharide polymer (agar and chitosan) results shown slower release
than blending of polysaccharide polymer alone. Among the three blend hydrogels, the slowest release was observed from the blend
hydrogel of gelatin-agar and gelatin chitosan polymers with a drug of 3:3 ratio. The swelling behavior was strongly dependent on the
polymer concentration in the formulations and the pH of the medium. Then the in-vitro release experiment revealed that the swelling is
the main parameter controlling the release rate of ranitidine hydrochloride from the hydrogel. The in-vivo study (pylorus ligation method)
shown that the oral administration of two different formulation did have signicant effect on properties of stomach in total acidity, free
acidity secretion, gastric pH, juice volume and ulcer index. These ndings were also conrmed by histological studies. From this study,
it was clear that blend hydrogel formulations had signicant anti-ulcer activity in animal models which might be due to its anti-secretary
activity.
Keywords: Hydrogel; Polymer blend; Ranitidine hydrochloride; Pylorus ligation method; Natural polymers
_____________________________________________________________________________________________________________
1. Introduction
Nowadays, hydrogels have become popular carriers
for drug delivery applications due to their biocompati-
bility and resemblance to biological tissues [1-6]. Hydro-
gels are three-dimensional hydrophilic polymer networks
that contain many pores hundreds of micrometers
in diameter [7-9] and swell in water or biological
uid without dissolving due to chemical or physical
cross links [10]. When the polymer network comes in
contact with aqueous solutions, the thermodynamic
compatibility of the polymer chains and water causes
the polymer to swell. As water penetrates inside the
glassy network, the glass transition temperature of the
polymer decreases and the hydrogel becomes rubbery.
Hydrogels can be used as a gastric retention device and
control the release kinetics due to their three-dimensional
structure [11]. Generally, drugs administered orally
are not adequately absorbed into the body because the
pulsatory force of the stomach in an acidic environment
easily breaks the carrier structures [12-15]. In addition
rapid gastrointestinal transit can result in incomplete
drug release from a device above the absorption zone,
leading to diminished efciency of the administered
dose. Therefore, different approaches have been
proposed to retain the dosage form in the stomach.
These include bioadhesive system, floating system,
swelling and expanding system [16]. Swelling devices
have frequently been used as a diet aid, sustained and
controlled release platform for local treatment in the
stomach and in the GI tract, colon-specic delivery,
pulsed & triggered drug delivery system and recently as
targeted gastro retentive device [17].
Hydrogel-based devices belong to the group of the
swelling-controlled drug delivery system [18]. Hence
after administration, hydrogels absorb a large volume
of environmental uids, which expand their volumes
__________
*Corresponding author. Address: GIET School of Pharmacy,
NH-5, Chaitanya Nagar, Rajahmundry 533294, India.
Tel: +91-883-2484444, 6577444; Fax: +91- 883-2484739
E-mail: mddhanaraju@yahoo.com
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considerably over very short time; their sheer bulk
hinders their transport to the next organ via the narrow
pylorus. This unique swelling property allows them to be
used as gastric retention carriers providing a sustained
release through long residence in the stomach [19].
Klausner et al [9] also reported that the Expandable
gastro retentive dosage forms have their size increased
by swelling, prolonging their gastric retention times.
After drug release, their dimensions are reduced
with evacuation from the stomach. Due to excellent
properties compared with homo-hydrogels derived from
single polymer, heterogeneous hydrogels derived from
polymer blends, block copolymers, or interpenetrating
polymer networks (IPN) have drawn much attention in
drug delivery system [20-24]. Polymer blend hydrogels
have more attracted attention due to their unique
properties. As a result of blending or interpenetrating
of more than two polymers have increased synergistic
properties and more complicated net work structures.
Interpenetrating polymer networks are defined as
a mixture of two or more inter winding cross linked
polymers where one of the network polymers is cross
linked in the presence of the other, which could help
improve the mechanical strength and resiliency of
the polymer [25]. Several works has been carried out
to study the gel formation by natural polymers and
biopolymers, such as polysaccharides and proteins,
which include the methods of inducing gelation in
aqueous solutions [26-29]. The use of natural polymers
in the design of hydrogels has received much attention
due to their large number of derivatizable groups, a
wide range of molecular weight, varying chemical
compositions, low toxicity, high stability, excellent
biocompatibility and biodegradability [30-32].
Ranitidine hydrochloride (RHCl or R), a specic H2-
receptor antagonist used to treat peptic and duodenal
ulcers, was chosen as the model drug in this study.
Bioavailability of 100 mg immediate-release ranitidine
was 51%–58% in the fasted condition. Ranitidine is
absorbed only in the initial upper part of the small
intestine [33]. The sustained-release dosage forms of
clinically acceptable RHCl designed with conventional
technology may not meet the desired requirements.
Consequently, prolonging ranitidine delivery into the
upper small intestine may result in increased absorption
while reducing frequent dosing and side effects. In
addition the gastro retentive drug delivery system helps
to retain the drug in the stomach and enhance the oral
sustained delivery of drugs in a particular region of the
gastrointestinal tract in that way the drug is released
continuously before it reaches the absorption window
and ensure optimal bio-availability [16,33]. Hence the
present study was carried out on the development of
gastro retentive delivery of polymeric blend hydrogel
from a pair of natural polymers gelatin, agar, chitosan
and the drug ranitidine hydrochloride (RHCl) in order
to overcome the problems associated with conventional
dosage form.
2. Material and methods
2.1. Materials
Chitosan (molecular weight: 65–90 kDa, viscosity
of 1% w/v aqueous solution in 2% (v/v) acetic acid:
130 mPa.s, deacetylation degree > 80%) was received
from India sea foods, cochin. agar and gelatin (type A,
approx.175 bloom) were received from Sigma–Aldrich,
Germany and used without any further purication.
Ranitidine hydrochloride was received as a gift sample
from Cadila Pharmaceuticals Ltd, Ahmedabad, India.
All other chemicals used were of analytical grade.
2.2. Hydrogel preparation
The hydrogels used in this study were prepared
from gelatin, agar and chitosan or their two component
blends. These hydrogels served as drug release matrices
after incorporating an appropriate amount of the drug,
RHCl. In this method 0.600 g of one gelling material
or a mixture of two of them was mixed with 20 ml
of RHCl aqueous solution prepared previously, so
that in all the obtained gel samples, the total polymer
concentration are all the same. For the single-polymer
systems, the mixture (polymer and RHCl solution) was
slowly heated to around 60, 80 or 90˚C for gelatin,
chitosan and agar hydrogels, respectively; for a blend
hydrogel, the higher melting temperature between
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two component polymers was adopted as the heating
temperature. Gentle stirring was needed here in order
to avoid bubbles in the nal gel solutions. After stirring
for about one hour, the optically clear solutions were
obtained. The resultant solutions were poured into an
upright placed glass syringe with a top cut off (machined
perpendicularly to the cylinder axis), which was kept
in an oven at 60˚C before use. The warm polymer
solutions in the syringe were allowed to evaporate and
equilibrate at the ambient temperature (about 25˚C) to
form a gel. The hydrogel samples based on the single
polymers (i.e. gelatin, agar and chitosan) are designated
as GR-type, AR-type and CR-type, respectively. These
hydrogels prepared based on two-component blend are
called GAR, GCR and CAR hydrogels for the blends
of gelatin–agar, gelatin-chitosan and chitosan-agar with
drug (RHCl or R) respectively. Table 1 shown the sample
designation and compositions for all the hydrogels
prepared in this study. For example, GA33R represents
the hydrogel containing a polymer blend consisting of
30wt. % gelatin, 30wt. % agar and appropriate amount
of the drug. These solid hydrogels were cut into the
disk-shaped samples with a sharp blade for the use of
following drug release experiments.
2.3. Swelling behavior study
The swelling characteristics of hydrogels were
studied both in the simulated gastric and intestinal pH
conditions using buffer pH 1.2 and pH 7.4, respectively.
Hydrogel were allowed to swell completely for about
24 h to attain equilibrium at 37 ± 0.1˚C. Adhered
liquid droplets on the surface of the particles were
removed by blotting with tissue papers and the swollen
hydrogels were weighed and dried in an oven at 60˚C
for 5 h until there was no change in the dry mass of
the samples. From the equilibrium mass%, M1 of the
sample, water uptake, S was calculated by measuring
the dry mass, M0 using the equation:
2.4. Drug release experiments
The in-vitro release hydrogel was carried out in
triplicate in stirred dissolution cells at 37 ± 0.1˚C by
suspending 1 g weight of disc-shaped hydrogel samples
(2.5 mm in thickness, 23 mm in diameter and 1 g in
weight) into a beaker containing 50 ml of release media
(pH 1.2 and 7.4) and distilled water. At certain time
intervals, 3ml solution was taken out from each release
system and the amount of RHCl released at that time
was determined by a UV spectrophotometer at 313 nm.
An equal volume of fresh medium was added to the
release system to maintain constant volumes.
2.5. In-vivo studies
2.5.1. Animals
Healthy Wister albino rats of either sex weighing
between (150–200 g) were used for present study. These
animals were used for anti-ulcer activity. The animals
were kept in polypropylene cages in a room maintained
under controlled atmospheric conditions in Research
Lab at GIET School of Pharmacy, Rajahmundry (A.P.)
India. The following study was designed according to
a standard method described by Zimmerman (1983).
%S = Mt – M0
M0
_________ ×100%
Table 1
Preparation of hydrogels composition and sample designation.
Gels designation
Gel composition Drug
(g)
Gelatin
(g)
Chitosan
(g)
Agar
(g)
Single
hydrogels
GR-type 0.6 — — 0.15
CR-type —0.6 —0.15
AR-type — — 0.6 0.15
Blend
hydrogels
GA 5:1 R 0.5 —0.1 0.15
GA 4:2 R 0.4 —0.2 0.15
GA 3:3 R 0.3 —0.3 0.15
GC 5:1 R 0.5 0.1 —0.15
GC 4:2 R 0.4 0.2 —0.15
GC 3:3 R 0.3 0.3 —0.15
CA 5:1 R —0.5 0.1 0.15
CA 4:2 R —0.4 0.2 0.15
CA 3:3 R —0.3 0.3 0.15
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The animals were stabilized for a week. They were
maintained in standard conditions at room temperature
and relative humidity at 60% ± 5% for 12 h light dark
cycle. Animals were provided with standard rodent
pellet diet (Amrut, India) and the food was withdrawn
18–24 h before the experiment though water was
allowed ad libitum. All experiments were performed
in the morning according to current guidelines for the
care of laboratory animals and the ethical guidelines
for investigations of experimental pain in conscious
animals [34]. The experimental protocol was approved
by the institutional animal ethics committee (IAEC)
GIET School of Pharmacy, Rajahmundry (A.P.), India,
vide approval number-1069/AC/07/CPCSEA.
2.5.2. Dosage
In the experiment, the rats were divided into four
groups (n = 6). Group 1 was the positive control group
which received saline (1 ml/kg, p.o.). Group 2 was the
standard control group which received ranitidine HCl
in the dose of 100 mg/kg body weight (p.o.). Groups 3
and 4 received GCR formulation and GAR formulation
in doses of 50 mg/kg body weight (p.o.) respectively.
2.5.3. Pylorus ligated (PL)-induced ulcers
Rats were deprived of food, but not water, for
about 18 h before the experiment. On day six, the rats
were kept for 18 h fasting and care was taken to avoid
coprophagy. Animals were anaesthetized using diethyl
ether, the abdomen was opened and pylorus ligation
was done without causing any damage to its blood
supply. The stomach was replaced carefully and the
abdomen wall was closed in two layers with interrupted
sutures. The animals were deprived of water during the
post-operative period (modified Shay et al., 1945 modal [35].
After 4 h, stomach was dissected out and the contents
of the stomach were collected and centrifuged. The
volume of the gastric juice was measured and this was
used for estimation of free acidity and total acidity [36].
Then cut open the stomach along the greater curvature
and ulcers were scored by a person unaware of the
experimental protocol in the glandular portion of the
stomach. Ulcer index is calculated by adding the total
number of ulcers per stomach and the total severity of
ulcers per stomach. The pooled group ulcers core is
then calculated according to the method of Sanyal et al [37].
2.5.4. Histopathological evaluation
The gastric tissue samples were fixed in neutral
buffered formalin for 24 h. Sections of tissue from
stomachs were examined histopathologically to study
the ulcerogenic and/or anti-ulcerogenic activity of
formulation. The tissues were xed in 10% buffered
formalin and were processed using a tissue processor.
The processed tissues were embedded in paraffin
blocks and about 5-µm thick sections were cut using
a rotary microtome. These sections were stained with
hematoxylin and eosin using routine procedures.
The slides were examined microscopically for
histopathological changes using microscope with
digital camera (Nikon Microscope; ECLIPSE 80) for
photography.
2.6. Statistical analysis
All values were reported as mean ± SEM. The sta-
tistical signicance of differences between groups was
assessed using one-way ANOVA. A value of P < 0.05
was considered signicant.
3. Results and discussion
In this study, the model drug RHCl was selected as
suitable candidate for gastro retensive swelling system
(hydrogel). The probable reason behind this selection
is colonatic metabolism of ranitidine, which is partly
responsible for the poor bioavailability of RHCl from
the colon. Dasharath et al [16] reported that the drug
selected for sustained release formulation should
posses absorption window either in colon or throughout
the GIT because most of these oral sustained release
formulation releases the drug at the colon. The model
drug RHCl is absorbed in only the initial part of the
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small intestine and has 50% absolute bioavailability.
These properties of RHCl refuse to accept the tradi-
tional approach to sustained release delivery [38-40].
Controlled and targeted delivery systems to stomach
could be achieved via the prolongation of the gastric
residence time. Such retention systems are more
suitable for drugs which exert a local effect in the
stomach. Among the various systems one of the
challenging systems is swellable system which includes
the products that swell after swallowing to an extent
that prevents the exit from the stomach through the
pylorus [41]. This results in retention of dosage form
in stomach for prolonged period. This favours the
retention of drug RHCl in the stomach and help to
interact with the H2 histamine receptor for prolonged
period.
In addition, size of dosage form is also one of
the factors among the other determinants of gastric
retention. Small size tablets are emptied from the
stomach during the digestive phase, where as large size
dosage forms are expelled during the house keeping
waves. If the dosage form is larger than the pylorus
opening, it cannot pass through pylorus, thereby,
the residence time in stomach increases. This can be
achieved by the swallable tablets, which are able to
swell at increases in size [41]. In addition to swelling,
the gel forming property of polymer can retain the drug
molecules with in dosage form, there by sustaining the
release of drug from the formulations.
The percent cumulative release profiles of RHCl
from 3:3 ratio of three two component blend hydrogels
(GA33 R, GC33 R, CA33R) and its corresponding
single component hydrogels (GR, CR, AR) at 37 ± 0.1˚C
is shown in Fig. 1A-C. From this gure a signicant
decrease in the release rate of RHCl was observed when
a blend hydrogel was used which may be due to difcult
in movement of the drug molecules from the hydrogel
network. From the Fig. 1, it was clearly understood that
the blending of single polymer releases the drug rapidly
due to negligible hydrodynamic hindrance of the drug
movement in the hydrogel network structure. Similar
nding was reported by Sjoberget et al [42]. The slow
drug release obtained from the polymer blend hydrogel
preparation suggest that no negligible hydrodynamic
hindrance of the drug movement in the hydrogel
network and produced extended pathway for the drug
to move through the polymer network. In addition from
Fig. 1 shown that adding of agar and chitosan (polysaccha-
ride component) to gelatin (protein) has signicantly
decreased the drug release rate when compare to adding
of agar and chitosan (two polysaccharide components)
due to similar IPN structure exist between two poly-
saccharides, which results in rapid drug release.
The release proles of three different weight ratio of
(5:1, 4:2, 3:3) RHCl dispersed blend hydrogel
formulation in distilled water at 37 ± 0.1˚C is shown in
Fig. 2A-C, where gelatin or chitosan was used as rst
polymer while agar or chitosan was used as second
polymer. Fig. 2A, 2B, 2C shows the release proles
for GAR hydrogel (gelatin and agar) GCR and CAR
hydrogels respectively. In order to evaluate the effect
of blend composition on drug release study, the above
three weight ratios of blending was selected and its
results clearly shown that reduced release rate with
increasing the content of the polysaccharide content
(10% < 20% < 30%), the release prole of RHCl is
also significantly lowered. Moreover, the release of
RHCl from CAR hydrogel shown insignicant effect
on blending ratio, which might be due to molecular
similarity between chitosan and agar i.e. same IPN
structures exist between chitosan and agar. Among
the three ratio, the 3:3 ratio gives the slowest release
profile which indirectly indicating the optimal IPN
formation. The reason behind this result revealed that
the mixture of equal amount of two inter winding
cross linked polymer participates the complete IPN
network structure formation. Where one of the network
polymers is cross linked or interpenetrated physically
in the presence of the other that could help improve
the complete IPN network structure. But in the case of
5:1, 4:2 ratio, the second polymer concentration has a
less quantity than the rst polymer. Hence the second
polymer amount could not be able to involve in the
formation of complete IPN network structure with the
rst one and may be the reason for the increased drug
release. According to this concept, among the three
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0 20 40 60 80 100 120 140 160 180 200
0
20
40
60
80
100
120
GR
AR
GAR
Time (min)
Cumulative drug released (%)
0 20 40 60 80 100 120 140 160 180 200
0
20
40
60
80
100
120
GR
CR
GCR
Time (min)
Cumulative drug released (%)
0 20 40 60 80 100 120 140 160 180 200
0
20
40
60
80
100
120
CR
AR
CAR
Time (min)
Cumulative drug released (%)
(A)
(B)
(C)
0 20 40 60 80 100 120 140 160 180 200
0
20
40
60
80
100
120
5:1
4:2
3:3
Time (min)
Cumulative drug released (%)
0 20 40 60 80 100 120 140 160 180 200
0
20
40
60
80
100
120
5:1
4:2
3:3
Time (min)
Cumulative drug released (%)
0 20 40 60 80 100 120 140 160 180 200
0
20
40
60
80
100
120
5:1
4:2
3:3
Time (min)
Cumulative drug released (%)
(A)
(B)
(C)
Fig. 2. Effect of blend compositions of percentage release of
RHCl from hydrogels based on (A) gelatin-agar-RHCl; (B)
gelatin-chitosan-RHCl; (C) chitosan-agar-RHCl at 37 ± 0.1˚C in
distilled water (mean ± SD, n = 3).
Fig. 1. Cumulative percentage release of RHCl from hydrogels
based on (A) gelatin-agar-RHCl; (B) gelatin-chitosan-RHCl; (C)
chitosan-agar-RHCl at 37 ± 0.1˚C in distilled water. (mean ± SD,
n = 3).
ratios, the 3:3 ratio only sustains the drug release from
the polymer network.
According to the result of blend composition and
blend ratios of polymer, among the three formulation
3:3 ratio of GAR and GCR formulation was selected
to study the in-vitro release of RHCl dispersed blend
hydrogel formulation at pH 1.2 and pH 7.4 buffers
at 37 ± 0.1˚C and results are presented in Fig. 3. It
has been observed from the Fig. 3, that the amount
of drug released from the blend hydrogel is higher in
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pH 1.2 solutions as compared to the release of drug
in solution of pH 7.4. The trends obtained are not
corresponding to the swelling pattern of the blend
hydrogels where the swelling has been observed
higher in pH 7.4 buffers. This may be due to the
more solubility of ranitidine hydrochloride in pH 1.2
buffers. At pH 1.2 the decreased swelling rate and
increased drug release in sustainable manner shown the
controlled releasing property of polymer with complete
network IPN structure due to strong hydrogen bond
and the water solubility property of drug. It has been
observed from the result that the selected ratio 3:3
prevent the formation of density or the complexity of
the gel network due to IPN structure thereby which
increase the drug release/molecular diffusion of a drug
immobilization in the hydrogel. The result shown the
increased swelling rate and controlled drug release
at pH 7.4 due to hydrophilic nature of the polymer,
water solubility property of the drug and formation of
complete network IPN structure. It favors absorption of
the drug in the initial upper part of small intestine (large
absorption site) and increases the bioavailability of the
drug. The retention of RHCl hydrogel preparation in
stomach and in colon for prolonged period may help
to treat not only the peptic ulcer but also the duodenal
ulcer.
Fig. 4 shown that the swelling ratio of the composite
hydrogel was gradually increase when changing the pH
from acidic (1.2) to basic (7.4) along with an increase
of the second polymer (polysaccharide), whereas no
difference was found between these three component
blend hydrogel. The extent of swelling was related
to the polysaccharide component concentration and
degree of polymer hydration. The result of decreased
swelling degree at pH 1.2 seemed that it had stronger
hydrogen bonds in addition to at a certain pH range
4–6, the majority of the base and acid groups are as
non-ionized forms, so hydrogen bonding between
amine and carboxylic acid may lead to a kind of cross
linking followed by a decreased swelling. At higher
pH, the carboxylic acid groups become ionized and
the electrostatic repulsive force between the charged
sites (COO-) causes increasing in swelling. Our nding
coincides with Patel and Patel [43] observation.
They reported that the swelling of the polymers
increases with the increase in sterculia contents in the
composition of polymer matrix. This is probably due
to the reason that higher degree of gum hydration has
occurred in the hydrogels prepared with higher gum
contents, which has increased the number of intimate
contacts between particle of gum and water, and led to
high swelling.
0 40 80 120 160 200 240
0
20
40
60
80
100
120
GAR
GCR
pH 1.2 pH 7.4
Time (min)
Cumulative drug released (%)
Fig. 3. In-vitro release of ranitidine hydrochloride from GAR
and GCR blend hydrogels formulations at pH 1.2 and 7.4 buffer
medium at 37 ± 0.1˚C (mean ± SD, n = 3).
0
100
200
300
400
500
600
700 CAR
GCR
GAR
pH 1.2 pH 7.4
CAR GCR GARCAR CAR GCR GAR
5:1
4:2
5:1
5:1
5:1
5:1
3:3
4:2
4:2
4:2
4:2
4:2
3:3
3:3
3:3
3:3
3:3
5:1
Medium
Water uptake (%)
Fig. 4. Water uptake percentage properties of different weight
ratio of CAR, GCR and GAR blend hydrogel formulations in
pH 1.2 and 7.4 buffer medium at room temperature. Bar diagram
represents the groups mean ± S.D (n = 3).
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In addition, natural polymers are normally high
molecular weight materials and generally swell slowly
to their equilibrium. With no doubt, the hydrophilic con-
tent of the hydrogel will affect the intermolecular forces
responsible for diffusion and swelling. As hydrophilicity
of the hydrogel increases, the interaction between water
and hydrogel will increase too; this facilitates water
diffusion and leads to greater swelling. Omidian and
Park [17] reported that the drug is water-soluble,
diffusion will be the primary approach and apparently,
as swelling increases, drug release will be the more
diffusion-controlled for water-soluble drugs. The
initial decrease in swelling at pH 1.2 and later increase
in swelling at pH 7.4 shown initial retarded release
(or sustained release) of drug followed by controlled
release of drug which was conrmed by the result of
release study (Fig. 3), at the same time which help to
increase the bioavailability of the drug. Moreover the
blend hydrogel preparation increases the residence time
at the stomach there by which prolong the H2-receptor
antagonist drug RHCl action on histamine H2-receptor.
In our in-vivo study, RHCl is used as acid reducing
agent and which was reported that this drug in a reverse
manner change the gastric pH. Hence estimation
of acid secretion is a valuable part of the study to
clarify the mechanism of action of the blend hydrogel
formulations. Among the different ulcer induced
method, the pyloric ligation induced gastric ulcer
method was selected since this method was particularly
used to study the formulation effect on gastric secretion.
The ligation of the pyloric end of the stomach causes
accumulation of gastric acid in the stomach that
produces ulcers. Agents that reduce secretion of gastric
aggressive factors such as acid and pepsin (anti-secretory)
and/or increase secretion of mucin (cytoprotective)
are effective in reducing development of gastric ulcers
[35,48-54]. Due to usage of acid reducing nature of
drug we concentrated only on the anti-secretory study
of gastric ulcers. From this study, oral administration
of two different formulation did have significant
effect on properties of stomach in acid secretion (total
acidity, free acidity), gastric pH, juice volume and
ulcer index. When compared to these two formulation
group with control group its reduction level showed no
signicant difference that the control group and two
formulation groups significantly decreased the total
acidity and free acidity, this suggests that it having an
anti-secretory effect (Table 2). Its antiulcer activity is
further supported by histopathological study shows
that protection of mucosal layer from ulceration and
inammation. Macroscopical change of pylorus ligation
was shown in Fig. 5A-D. Histopathological changes
on pylorus ligation model showed the degeneration,
hemorrhage, edematous appearance of the gastric
tissue, where as GA-R formulation (50 mg/kg) and
GC-R formulation (50 mg/kg) treated groups showed
regeneration and prevents the formation of hemorrhage
and edema and it was shown in Fig. 6A-D.These results
showed that the blend hydrogels were able to protect
ulcer formation by pyloric ligation method.
Table 2
Effects of oral administration of GAR and GCR blend hydrogel formulation on volume, acidity, and pH of gastric contents in pylorus
ligated (modied Shay modal) rats..
Group Treatment Mean volume of
gastric juice (ml)
pH of gastric
juice
Mean ulcer
index
Mean free acidity
(meq/l)
Mean total acidity
(meq/l)
I Control (pyloric ligation) 5.08 ± 0.01 2.4 ± 0.06 3.49 ± 0.11 80.28 ± 3.70 117.45 ± 1.89
II RHCl (100 mg/kg) 2.31 ± 0.06*** 5.2 ± 0.07*** 1.45 ± 0.06*** 44.74 ± 1.76*** 88.66 ± 1.56***
III GAR (50 mg/kg) 1.54 ± 0.04*** 4.6 ± 0.09*** 1.69 ± 0.04*** 39.80 ± 0.49*** 72.83 ± 0.94***
IV GCR (50 mg/kg) 1.58 ± 0.04*** 4.8 ± 0.06*** 1.68 ± 0.04*** 38.93 ± 0.50*** 73.00 ± 1.18***
Values are express as mean ± SEM of 6 observations, Statistical comparisons as follows: signicant at *P < 0.05, **P < 0.01,
***P < 0.0001 compared to control group.
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4. Conclusion
In this study, a blend hydrogel of three different ratio
was fabricated successfully by blending the drug (RHCl)
with two of three polymers: gelatin, agar and chitosan.
The blending effect on RHCl release shown slower
release when gelatin blended with a polysaccharide
polymer (agar and chitosan) than blending gelatin itself.
But no signicant difference produced when blending
of two polysaccharide polymer (agar and chitosan)
then blending agar and chitosan itself. The cumulative
percentage drug release results clearly indicated the
sustained and controlled release of RHCl from GAR
and GCR formulation at pH 1.2 and pH 7.4 buffer
medium. The in-vivo anti-ulcer activity evaluation
showed that the blend hydrogel formulation (GAR &
GCR) were effective to protect rat stomach against ulcer
formation in pylorus ligated rats and this nding was
further conrmed histologically. Blend hydrogel based
gastric retensive drug delivery system provides the
possibility of enhancing the bioavailability and control
the release of RHCl by prolonging the gastric emptying
time of the dosage form, ensuring availability of drug at
the absorption site for the desired period of time. From
the present investigation it may be concluded that the
blend hydrogel formulation is an effective formulation
in the design of a gastric retensive drug delivery system
of highly water soluble drugs like RHCl.
Fig. 6. Histopathology of pyloric ligation induced ulcer model (Hematoxin & Eosinx 10)
Fig. 5. Macroscopical appearance of pylorus ligation induced ulcer model (Hematoxin & Eosinx 10).
(D) GAR (50 mg/kg)
shows protected mucosal
layer
(C) GCR (50 mg/kg)
shows protected mucosal
layer
(B) RHCl (100 mg/kg)
shows protected mucosal
layer
(A) Control (P.L.) shows
severe damage
of mucosal layer
(D) GAR (50 mg/kg)
shows protected mucosal
layer
(C) GCR (50 mg/kg)
shows protected mucosal
layer
(B) RHCl (100 mg/kg)
shows protected mucosal
layer
(A) Control (P.L.) shows
severe damage
of mucosal layer
(D) GAR (50 mg/kg)
shows protected mucosal
layer
(C) GCR (50 mg/kg)
shows protected mucosal
layer
(B) RHCl (100 mg/kg)
shows protected mucosal
layer
(A) Control (P.L.) shows
severe damage
of mucosal layer
(D) GAR (50 mg/kg)
shows protected mucosal
layer
(C) GCR (50 mg/kg)
shows protected mucosal
layer
(B) RHCl (100 mg/kg)
shows protected mucosal
layer
(A) Control (P.L.) shows
severe damage
of mucosal layer
(D) GAR formulation
group rats (50mg/kg) shown
no significance change in
histopathology when
compare to standard control
group almost normal
appearance
(C) GCR formulation group
rats (50mg/kg) shown no
significance change in
Histopathology when
compare to standard
control group almost
normal appearance
(B) Standard control group
rats (RHCl (100mg/kg)
shown significance change
in histopathology almost
normal appearance
(A) Control grouprats
(pylorus ligation) shown
mucosal ulceration and
inflammation
(D) GAR formulation
group rats (50mg/kg) shown
no significance change in
histopathology when
compare to standard control
group almost normal
appearance
(C) GCR formulation group
rats (50mg/kg) shown no
significance change in
Histopathology when
compare to standard
control group almost
normal appearance
(B) Standard control group
rats (RHCl (100mg/kg)
shown significance change
in histopathology almost
normal appearance
(A) Control grouprats
(pylorus ligation) shown
mucosal ulceration and
inflammation
(D) GAR formulation
group rats (50mg/kg) shown
no significance change in
histopathology when
compare to standard control
group almost normal
appearance
(C) GCR formulation group
rats (50mg/kg) shown no
significance change in
Histopathology when
compare to standard
control group almost
normal appearance
(B) Standard control group
rats (RHCl (100mg/kg)
shown significance change
in histopathology almost
normal appearance
(A) Control grouprats
(pylorus ligation) shown
mucosal ulceration and
inflammation
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