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Purpose: To prepare, using non-solvent addition technique, diclofenac sodium-ethylcellulose microparticles with modified drug release properties. Methods: Microparticles were prepared by non-solvent addition phase separation method and characterized by micromeritics, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), dissolution test and thermal analysis. Results: The microparticles were whitish, irregular, aggregated, and in the size range of 390 - 442 μm size. Drug embedment efficiency was 89 - 91 %. Characterisation studies indicate that there was no strong chemical interaction between the drug and the polymer in the microparticles. Polymer concentration and sustained release behavior were directly proportional. Conclusion: Non-solvent addition phase separation is a suitable method for preparing diclofenac sodium-ethylcellulose multi-unit controlled release drug delivery system. [ABSTRACT FROM AUTHOR]

Purpose: To employ response surface methodology (RSM) for statistical optimization of formulation factors in the preparation of celecoxib-loaded microspheres. Methods: Celecoxib microspheres were prepared by solvent evaporation method. Biodegradable/biocompatible polymers, Eudragit L-100 and polyvinyl pyrrolidone, were used in the encapsulation procedure. A central composite design employing Stat-Ease design Expert®, version 7.0.3 having a unit value of a was used according to reference protocols to assess the influence of two independent variables (i.e., the concentration of the two polymers used) on four dependent variables (i.e., recovery, encapsulation efficiency and % drug released). The polymers used were Eudragit-L100 (X1) and polyvinyl pyrrolidone (X2). The microspheres were characterized for size, shape, recovery (%), entrapment efficiency and drug release. Results: The recovered total weight of microspheres ranged between 49.4 ± 3.1 and 91.1 ± 4.8 %, and it decreased with increase in the concentration of PVP. Entrapment efficiency was in the range of 54.1 ± 2.9 to 95.6 ± 3.7 %, and was also dependent on polymer concentration. The release of celecoxib increased with decrease in Eudragit L-100 concentration and increase in PVP concentration. Higuchi model was the best-fit drug release from all the formulations. Korsemeyer-Peppas release exponent (n) indicates that drug release pattern was non-Fickian diffusion. Conclusion: Using RSM, it is possible to optimize the drug release properties of celecoxib-loaded microspheres. A celecoxib-loaded microsphere formulation with optimum recovery, entrapment efficiency and release behavior was proposed. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the pharmacokinetics of of a developed metoprolol and a reference standard (Mepressor®). Methods: Metoprolol tartrate-loaded Eudragit® FS microparticles were formulated and compressed into tablets. The tablets were tested for their physicochemical properties according to United States Pharmacopoeia (USP) criteria. In vivo studies of the formulations were carried out in 28 young healthy fasting male volunteers based on a randomized open label 4×4 crossover study design with a washout period of 7 days. Results: In vitro tests showed that the developed and reference standard of metoprolol tablets met compendia (USP) requirements. Zero order release of drug was observed from all the tablets. In vivo data demonstrated that there were significant (p < 0.05) differences in tmax, Cmax, MRT, AUC0-t, and AUC0-&infin; between the reference and test (developed) formulations. However, the 90 % class interval for the mean ratios of the ln-transformed Cmax, AUC0-t and AUC0-α for the reference, T1, T2, and T3 lied in the bioequivalence range (80 to 125 %) indicating bioequivalence between the compared formulations. Conclusion: It can be concluded from this single-dose study that the reference and test (developed) formulations met the predetermined criteria for bioequivalence in young healthy fasting male human subjects as the bioequivalence factor lie in the pre-determined limits for bioequivalence. Thus, the two formulations can be considered bioequivalent. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the penetration enhancing effect of two polysorbates polyoxyethylene 20 (POE-20) and polyoxyethylene 80 (POE-80)-on the in vitro percutaneous absorption of ascorbic acid (AA). Methods: For the permeation experiments, Franz diffusion cell covered with aluminum foil providing an effective diffusion area of 1.76 cm2 and hairless rabbit skin were used. A range of concentrations (1 – 5 %) of POE-20 and POE-80 was added to the ascorbic acid to determine their optimum enhancement concentration. Results: The cumulative amount of AA that diffused across the skin increased with increase in the concentration of the permeation enhancers. Without the enhancer, AA flux was 0.626 μg/cm2/h while mean permeability coefficient (Kp) was 2.09 × 10-6 cm/h. AA flux was 3.17 and 2.44 μg/cm2/h for POE-20 and POE-80, respectively, while mean permeability coefficient was 10.6 × 10-6 and 8.14 × 10-6 Kp, cm/h. Maximum flux (3.16 μg/cm /h) at POE-20 concentration of 5 % was obtained, with an enhancement ratio (ER) of 5.07 in relation to control (i.e., AA without enhancer). For POE-80 (5 %), maximum flux was 2.44 μg/cm2/h with an ER value of 3.89, compared to control. Conclusion: This study demonstrates that POE-20 and POE-80 exerted a penetration enhancing effect on the percutaneous absorption of L-ascorbic acid (AA). [ABSTRACT FROM AUTHOR]