Physicochemical Equivalence Studies of Two Amlodipine Tablet Formulations

Abstract

Introduction: Based on the international drug regulatory requirements, all generic pharmaceutical manufacturers are obliged to ensure that their generic products are similar or equivalent to the innovative brand. The quality of generic medicines should be comparable with the innovator brand and therefore interchangeable with the innovator. Based on the Biopharmaceutical Classification System (BCS), dissolution tests can be used as a replacement for in vivo studies for drugs that belong to the BCS class I. Dissolution tests are considered the most sensitive in vitro parameters that can be with the highest probability of correlation with in vivo bioavailability. The comparison of in vitro dissolution tests using similarity factor (f2) is very often used as the most important parameter that can reflect the existence of bioavailability. Aim of the Study: The aim of this study was to compare the physico-chemical characteristics of two amlodipine formulations made by the same manufacturer using the dissolution test and similarity factors to ascertain their in vitro similarity. Material and methods: Two different generic copies of amlodipine 5 mg tablets produced by the same pharmaceutical manufacturer were evaluated using pharmaceutical parameters such as: uniformity of active ingredient test, weight uniformity text, disintegration test, hardness test, tablet friability test, and in vitro dissolution test. Results: The results have shown that different salts and different manufacturing procedures do not have effect on in vitro equivalence of amlodipine tablets. The similarity factor (f2) at pH 4.5, 1.2 and 6.8 was 63.90, 53.87 and 57.57, respectively. Although these values demonstrated equivalence, statistically significant differences were found in the degree of dissolution rates of tablets formulation depending on time and pH values. The results of our study showed equivalence of dissolution profiles of different amlodipine formulations. Conclusion: The results of our study have shown that the equivalence of dissolution profiles exists, although there were statistical differences in some pharmaceutical parameters.