Statistical Evaluation of In-vitro Dissolution Profiles of Different Brands of Simvastatin 20 Mg Tablets Available in Local Market of Karachi

Objective: Simvastatin is lipid lowering agent that reduces the risk of total mortality and morbidity. For such a sensitive medicine, the availability of un-control brands, local and multinational is a point of thought. The objective of this study was to provide a comparative assessment of dissolution profile of six different brands of Simvastatin by applying dissolution profile comparison approach to check the possibility of interchangeability of different brands. Method: Dissolution was carried out with six units of each brand using USP apparatus-II (Paddle) at 37 ± 0.5°C in 900 ml phosphate buffer medium pH 7.0 with 0.5% SLS at 50 rpm. Samples were withdrawn from the dissolution medium at 5, 10, 15, 30, 45 and 60 min interval, and analyzed spectrophotometrically at 239 nm. Various statistical methods recommended by FDA such as Model-independent methods including difference f1 and similarity factor f2, Model dependent methods such as, First order, HixsonCrowell and Weibull methods and One way ANOVA were used for the comparison of in vitro dissolution profiles. Results: From results it was evaluated that all methods are useful and applicable in determination of similarity among all local test brands with innovator in dissolution and point up that model-independent method is simpler in interpretation in comparison with ANOVA and modeldependent method. ANOVA method presented similarity among all means of drug release with p-value >0.05. Model dependent methods are well explained and discriminative among various brands, Weibull is the best fit model on drug release data. The drug release mechanism was a detailed of Log dissolved amount of drug versus log time. Among all model dependent methods; Weibull is more sensitive and explanatory for release behavior and in determination between differences of two dissolution profiles. Conclusion: On basis of evaluation it was concluded that a low cost brand SIMB can be useful in lipid lowering therapy.