ABSTRACT
OBJECTIVE: Lamotrigine (LTG) an anticonvulsant drug with a dissociation constant (pKa: 5.7), suffers from enhanced blood plasma spike after each dose, when administered as fast release tablet. Being BCS class-II candidate and pH dependent solubility, development of release-controlled tablets of LTG is a major challenge. This investigation aims at designing the release-controlled tablet (RCT) formulation of LTG using a solid dispersion (SD) technique via addressing its solubility and release problems. MATERIAL AND METHODS: RCT of LTG was fabricated using SD blend of Eudragit RL and Eudragit RS and PVP K-30 with different polymer blend ratio (1:5 and 1:7). The optimization of RCT of LTG was performed using D-optimal mixture design with three independent variables, three response variables, and one constraint. The dissolution rate was determined and data were then fitted to different mathematical models. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) studies and tableting parameters were analyzed. RESULT: In vitro studies of predicted optimized batches (POBs) have shown that drug release over a period of 12hours was 88.05±3.4% in media I, 86.10±3.7% in media II and 85.84±4.2% in media III. An in vitro kinetic model equating R2-value for all the tested models indicated that the first order and Higuchi release kinetics model were the most appropriate. CONCLUSION: Based on the optimized formulation consisting of SD of LTG with Eudragit RL, Eudragit RS and PVP K-30, the release rate was consistently similar throughout the GI tract, regardless of the pH of the environment.
ABSTRACT
Objectives: Desoximetasone (DMS) is a widely recommended drug for the topical treatment of plaque psoriasis. However, low water solubility and short half life of DMS present major obstacles in the development of an effective topical formulation. Thus, there is a demand for the development of a safe and effective topical system to deliver hydrophobic DMS. The present study aimed to develop an Aloe vera-based emulgel formulation to ensure enhanced skin deposition of DMS for effective treatment of plaque psoriasis. Materials and Methods: Different formulations (DE1-DE4) of Aloe vera emulgel were prepared using dispersion technique, wherein varying concentrations of propylene glycol (6-14% w/w) and carbopol 934 (0.5-1.0% w/w) were used. Results: Zetasizer measurements revealed that the globule size of the formulations ranged from 10.34 µm±0.9 to 14.60 µm±1.4 (n=50). Extrudability analysis for the DE3 and DE2 formulations revealed an extrudability of 5.6±0.11 g/cm2 and 5.8±0.13 g/cm2, respectively. The pH of the formulations was recorded in the range of 5.8-6.8. Among these formulations, DE3 showed a maximum drug content of 94.64%±0.29 (n=3), and thus was used for further in vitro evalutions. A texture analyzer showed that an optimized DE3 formulation was firmer and exhibited optimal spreadability in comparison with the DE2 formulation. For DE3, the mean max force that represented "firmness" was recorded to be 833.37 g, where as the mean area, denoting "work of shear", was 324.230 g.sec. The DE3 formulation exhibited DMS permeation of 95.40±1.6% over a period of 7 h, as detrmined using an in house fabricated Franze diffusion cell. Evaluation of in vitro release kinetics revealed that the release of DMS fitted into the Korsmeyer-Peppas model. Conclusion: Physicochemical characteristics and enhanced in vitro permeation of DMS from Aloe vera emulgel highlight its suitability to be efficiently employed for the topical treatment of skin ailments.
ABSTRACT
BACKGROUND: Nifedipine is a potential therapeutic agent for the treatment of cardiovascular disturbances, although it suffers from short half-life (t1/2, 2 hr). OBJECTIVE: To address the problem, we first prepared nifedipine loaded sustained release microsponges and then formulated tablets for effective clinical application and patient compliance. METHOD: Preparations of microsponges were carried out using different compositions of nifedipine and polymer (1:1, 1:2 and 1:3 % molar ratio) using emulsion solvent diffusion technique. RESULTS: The microsponges with molar ratio 1:3 (formulation code: MF-3) found optimized as revealed by analyzing surface morphology, better powder flow properties (angle of repose; 28.80 ± 0.9, Hausner ratio 1.15 ± 0.2, % compressibility 15.28 ± 0.5% and higher % drug content (80 ± 1.9 %). Different batches of tablets were then formulated incorporating MF-3 microsponges and different proportions (10-50 %) of microcrystalline cellulose and starch as additives. Among tablet formulations, batch composed of 48% of MF-3, 30% of MCC, 20 % of starch and 2 % of talc (TF-33), showed 92.73 ± 2.19 % drug release during 24 hr in vitro release study in comparison to other batches including commercial formulation which was found to be released completely in 20 hr. Further, stability analysis revealed good drug retention of loaded nifedipine as well as consistent in vitro release pattern over a period of 90 days at 40°C and 75% RH. CONCLUSION: The microsponge tablet delivery system was found to be superior concerning the therapeutic advantage as well as manufacturing feasibility of nifedipine.