Fig 2 - uploaded by Xiao Yu (Shirley) Wu
Content may be subject to copyright.
Source publication
A detailed theoretical analysis of drug release from a two-dimensional membrane-reservoir tablet into a sink is presented. An entire process of drug release was modeled including a phase of drug release from a constant reservoir followed by a phase of non-constant reservoir. Explicit theoretical solutions were obtained for the first time for the tw...
Context in source publication
Context 1
... t lag and t burst are often referred to time lag and initial burst, illustrated in Fig. 2 as the intercepts on the x -axis of the plot of M vs. t . When all of dispersed drug is dissolved, the reservoir in the tablet becomes non-constant, i.e., C becomes a variable. As C is governed by the release rate in both the axial and the radial directions, the total amount of drug released from the tablet is no longer a simple summation of the amount of drug released from , and 3 . Instead, C has to be calculated as a function of time based on mass balance from the following ...
Similar publications
Although the solid dispersion method has been known to increase the dissolution rate of poorly water-soluble drugs by dispersing them in hydrophilic carriers, one obstacle of the solid dispersion method is its limited solubilization capacity, especially for pH-dependent soluble drugs.
pH-modified solid dispersion, in which pH modifiers are incorpor...
These days an alternative to soft capsules is liquid-filled hard capsules. Their filling technology was investigated earlier with highly viscous formulations, while hardly any academic research focused on low-viscosity systems. Accordingly, this work addressed the filling of such oils that are splashing during the dosing process. It was aimed to fi...
Citations
... As a control, an equal amount of rapamycin molecules dissolved in the release medium was applied to the air side of the membrane as a source of nonconstant activity (Fig. 5b). With the direct diffusion of drugs without the presolvation step, the release of rapamycin from the nonconstant liquid reservoir followed a first-order profile 46 and reached equilibrium after 19 h (Fig. 5c). In contrast, drug release from the solid reservoir was retarded because it must be solvated into drug molecules prior to diffusion. ...
Urethral stricture secondary to urethral injury, afflicting both patients and urologists, is initiated by excessive deposition of extracellular matrix in the submucosal and periurethral tissues. Although various anti-fibrotic drugs have been applied to urethral stricture by irrigation or submucosal injection, their clinical feasibility and effectiveness are limited. Here, to target the pathological state of the extracellular matrix, we design a protein-based nanofilm-controlled drug delivery system and assemble it on the catheter. This approach, which integrates excellent anti-biofilm properties with stable and controlled drug delivery for tens of days in one step, ensures optimal efficacy and negligible side effects while preventing biofilm-related infections. In a rabbit model of urethral injury, the anti-fibrotic catheter maintains extracellular matrix homeostasis by reducing fibroblast-derived collagen production and enhancing metalloproteinase 1-induced collagen degradation, resulting in a greater improvement in lumen stenosis than other topical therapies for urethral stricture prevention. Such facilely fabricated biocompatible coating with antibacterial contamination and sustained-drug-release functionality could not only benefit populations at high risk of urethral stricture but also serve as an advanced paradigm for a range of biomedical applications.
... As a control, an equal amount of rapamycin molecules dissolved in release medium was applied to the air side of the membrane as a source of non-constant activity (Fig. 4b). With the direct diffusion of drugs without the pre-solvation step, the release of rapamycin from the non-constant liquid reservoir followed a first-order profile 48 and reached equilibrium after 19 h (Fig. 4c). In contrast, drug release from solid reservoir was retarded because it must be solvated into drug molecules prior to diffusion. ...
Urethral stricture, which afflicts both patients and urologists, involves excessive deposition of extracellular matrix in the submucosal and periurethral tissues. Although various anti-fibrotic drugs have been applied to urethral stricture by irrigation or submucosal injection, their clinical feasibility and effectiveness are limited. To prevent stricture after endoscopic therapy, urethroplasty, and traumatic catheterization, we designed a protein-based nanofilm-controlled drug delivery system and assembled it on the catheter to target inordinate extracellular matrix deposition. This approach is simple to manufacture and simultaneously integrates excellent anti-biofilm property into a urinary catheter in one step. Stable and controlled drug delivery over tens of days ensures optimal efficacy and negligible side effects. Anti-fibrotic catheters maintain extracellular matrix homeostasis by reducing fibroblast-derived collagen production and enhancing metalloproteinase 1-induced collagen degradation in a rabbit model of urethral injury, resulting in the greatest improvement in lumen stenosis than other topical therapies for urethral stricture prevention. Such biocompatible coating with antibacterial contamination and sustained-drug-release functionality could also be an advanced paradigm for a range of biomedical applications.
... The experimental release data were than fitted to selected kinetic models. The data were analyzed using zero order (11), first order (12), Higuchi (13) and Hixon-Crowell (14) mathematical models (Costa and Lobo, 2001;Dash et al., 2010;Zhou et al., 2010). The data were also fitted to Korsmeyer-Peppas model (15) to understand the drug release mechanism. ...
Bionanocomposites containing biopolymers and inorganic nanomaterials of natural origin are intensively studied as eco-firendly alternative to non-biodegradable materials for food packaging applications. The preparation and characterization of pectin and alginate films filled with halloysite (Hal) loaded with salicylic acid are presented here. Two types of Hal with different morphology, derived from Dragon and Dunino mines, were used for adsorption of the antimicrobial agent. The adsorption properties of the nanomaterials were comparable after their initial activation with sulphuric acid. The adsorption increased with increasing initial concentration of salicylic acid. The theoretical analysis of experimental data indicated good correlation with Freundlich isotherm and pseudo-second-order kinetic models. The in vitro release profiles differed depending on the type of biopolymer and the release medium. The release rates were slightly lower for materials with Hal Dunino than those of Hal Dragon in 20% v/v ethanol. Cumulative release was more controlled and prolonged with alginate films, especially in 50% v/v ethanol mimicking food with lipophilic properties. Moreover, alginate films demonstrated greater antimicrobial activity against selected food spoilage bacteria. Alginate materials were effective against four bacteria strains, while pectin films showed the ability of growth inhibition of only two strains tested.
... E xtended-release (ER) tablets are solid oral dosage forms formulated with excipients to extend drug release over a prolonged period after oral administration (1). Developing ER dosage forms is a challenge for formulation scientists given that tablets must be designed to release drugs slowly in the gastrointestinal (GI) tract; the control of drug release can be achieved mainly by formulation approaches like coatings, compressed coated tablets, osmotic pump systems, or hydrophilic polymers (2)(3)(4)(5)(6). ...
Developing extended-release (ER) formulations with appropriate release characteristics can be challenging for formulation scientists. The aim of this study was to demonstrate the use of computer-simulated dissolution profiles associated with statistical experimental design in the development of doxazosin ER tablet formulations. Experimentadoxazosin ER tablets were prepared and tested using USP Apparatus 2 with 900 mL of simulated gastric fluid without enzyme at 37 ± 0.5 °C and 75 rpm for 960 minutes. The results were used to optimize calibration constants for the ingredients in the simulation software, DDDPlus. Design Expert software was used to obtain different mixtures between lactose and HPMC K100M, creating seven formulations with dissolution profiles simulated in DDDPlus. After statisticaanalysis, an optimized doxazosin ER formulation was identified, manufactured, and tested for comparison with the predicted profile. A correlation coefficient of 0.99 was obtained for observed and predicted dissolution profiles of the optimized doxazosin ER formulation. The use of test simulations led to a 66.67% reduction in analyst working hours and 77.78% reduction in both equipment usage time and dissolution medium volume. Computer simulations associated with design of experiments can save time and reduce costs in the development of ER formulations.
... Depending on the properties of active ingredients and coating substrate as well as the physical dimensions of the formulation, drug release mechanisms can vary significantly. For rigid solid dosage forms containing poorly soluble drugs and hydrophobic substrate, a combination of drug dissolution and diffusion through intact films may be the dominant release mechanisms [40,41]. In the case of highly soluble drugs and osmotic substrates (e.g. ...
Water-soluble polymers are often used as pore formers to tailor permeability of film-forming hydrophobic polymers on coated dosage forms. However, their addition to a coating formulation could significantly increase the viscosity thus making the coating process difficult. Moreover, the dissolution of pore formers after oral administration could compromise film integrity resulting in undesirable, inconsistent release profiles. Therefore, a non-leaching, pH-responsive nanoparticulate pore former is proposed herein to preserve film integrity and maintain pH-dependent permeability. Poly(methacrylic acid)-polysorbate 80-grafted-starch terpolymer nanoparticles (TPNs) were incorporated within an ethylcellulose (EC) film (TPN-EC) by casting or spray coating. TPNs at 10%wt (pore former level) only increased viscosity of EC coating suspension slightly while conventional pore formers increased the viscosity by 490% to 11,700%. Negligible leaching of TPNs led to superior mechanical properties of TPN-EC films compared to Eudragit® L-EC films. As pH increased from 1.2 to 6.8, TPN-EC films with 10% pore former level exhibited an 8-fold higher diltiazem permeability compared to Eudragit® L-EC films. The pH-dependent drug release kinetics of diltiazem HCl beads coated with TPN-EC films was tunable by adjusting the pore former level. These results suggest that the TPNs are promising pH-sensitive nanoparticulate pore formers in EC-coated dosage forms.
... The multi-particulate prolonged release reservoir type preparations combine the advantages of the multiparticulate preparations with the drug release modulation capabilities offered by the polymeric coated of reservoir type preparations [3,10,11]. ...
Background and aims:
Felodipine is a dihydropyridine calcium antagonist that presents good characteristics to be formulated as prolonged release preparations. The aim of the study was the formulation and in vitro characterization of a reservoir type prolonged release system with felodipine, over a 12 hours period using the Simplex method.
Methods:
The first step of the Simplex method was to study the influence of the granules coating method on the felodipine release. Furthermore the influence of the coating polymer type, the percent of the coating polymer and the percent of pore forming agent in the coating on the felodipine release were studied. Afterwards these two steps of the experimental design the percent of Surelease applied on the felodipine loaded granules and the percent of pore former in the polymeric coating formulation variables were studied. The in vitro dissolution of model drug was performed in phosphate buffer solution (pH 6.5) with 1% sodium lauryl sulfate. The released drug quantification was done using an HPLC method. The release kinetics of felodipine from the final granules was assessed using different mathematical models.
Results:
A 12 hours release was achieved using granules with the size between 315-500 μm coated with 45% Surelease with different pore former ratios in the coating via the top-spray method.
Conclusion:
We have prepared prolonged release coated granules with felodipine using a fluid bed system based on the Simplex method. The API from the studied final formulations was released over a 12 hours period and the release kinetics of the model drug substance from the optimized preparations fitted best the Higuchi and Peppas kinetic models.
... Again in 2005, they investigated dispersed drug release from two dimensional matrix tablets [11]. Recently Zhou et al. considered theoretical analysis of release kinetics of coated tablets containing constant and non-constant drug reservoirs [12]. Also Helbling et al. derived an explicit analytical solution for the case of controlled dispersed-drug release from planar non-erodible polymeric matrices based on Refined Integral Method [13]. ...
Heat-stable, multivitamin-loaded, and surface-coated liposomes tailored for pH-triggered delivery of both lipophilic and hydrophilic bioactives were synthesized from a cocktail of milk fat globule membrane (MFGM) phospholipids, supercritically extracted from buttermilk powder. Liposomes from MFGM-phospholipids (ML) were fabricated using a novel organic solvent free process based on venturi-based rapid expansion of a supercritical solution. A commercially available pH-responsive polymer, Eudragit® S100 was used to coat MLs (Eu-ML). Eu-MLs were heated to 60, 75, and 90 °C for 30 min and were observed to be heat-stable as established by CLSM images, structural characterizations, and encapsulation efficiency measurements. Coating of liposomes with Eudragit® S100 protected encapsulated payload from deleterious gastric environment and facilitated site-specific pH-triggered release in the simulated intestinal condition. This study established a green method to fabricate heat-stable liposomal vehicles for pH-triggered delivery of bioactive compounds with excellent potential for scale-up and applications in the food, pharmaceutical, and cosmetic industries.
Background:
In developing countries, particularly in Iraq, the use of generic medicines has been increasing in recent years, primarily as a cost-saving measure in healthcare provision. In the Iraqi market, famotidine tablets are available from different pharmaceutical companies. As a result, regular pre-marketing quality testing is required to check the quality and identify which product might safely substitute the innovator product in the event of the innovator brand’s unavailability or high cost.
Objective:
various quality control tests have been conducted to determine the Pharmaceutical Equivalence of the different generic and brands of Famotidine film-coated tablets marketed in Iraq.
Materials and Methods:
Four different samples of the most commonly available Famotidine 20 mg tablets in the Iraqi market were tested for drug contents, friability, and hardness. Additionally, the in-vitro drug release and kinetics were evaluated.
Results:
slight differences in the products’ content were found; however, they were within the acceptable requirement of British Pharmacopeia (BP) and The United States Pharmacopoeia (USP) 30, NF 25. Similarly, the friability and hardness were within the excellent range according to the B.P. and USP. The results of our study indicated that the tested brand (Famodin) and the three generic products (Famosam, Ulceran, and Famodar) of Famotidine tablets have a unique pattern of in-vitro release profiles. However, all the tested brands and generic pills complied with the USP specifications for the immediate release dosage forms except for Famosam. Release kinetic for the four tested products indicates first-order kinetic models.
Conclusion:
The findings revealed that nearly all of the tested Famotidine tablet brands and generics met the pharmacopeial requirements for oral tablets. As a result, if acquiring the innovative brand of famotidine tablets is difficult to obtain, healthcare providers may be advised to use the tested products instead.
