Development of Discriminative Dissolution Medium for Valsartan

Dissolution is a valuable qualitative tool to asses the biological availability and batch to batch consistency. Discriminative dissolution mediums are highly desirable to differentiate the dissolution profiles of two identical products which are varied in their composition, formulation technique, manufacturing process and site of manufacturing. The objective of present investigation is to develop discriminative dissolution medium for valsartan by using two different marked formulations named as VALZAAR and VALENT. The dissolution studies were performed in four dissolution mediums (0.1N HCl (pH 1.2), pH 4.5 acetate buffer, pH 6.8 phosphate buffer and distill water) at three different agitation speeds (50, 75,100 RPM). Model independent approaches such as difference factor (f1) and a similarity factor (f 2) were used to compare dissolution profiles. Among all the cases in pH 6.8 phosphate buffer at 100 rpm drug releases at faster rate and best suited to maintain sink conditions. Irrespective of other cases pH 4.5 acetate buffer at 50 rpm was considered as a discriminative dissolution medium because of its lesser similarity factor and higher difference factor. From the present experimental investigation the rate of dissolution was found to be influenced by pH of the dissolution medium and speed of the agitation. The usage of 4.5 acetate buffer at 50 rpm was found to be a discriminative dissolution medium for valsartan tablets.