Evaluation of In-vitro Bioequivalence of Commonly Prescribed Generics of Poorly Water Soluble Drug-Atorvastatin Calcium in Pakistan

Atorvastatin is a HMG-CoA reductase inhibitor which reduces the blood cholesterol levels and is commonly used for the treatment of hypertension. It is a poorly water soluble drug and has 14% oral bioavailability therefore mild formulation factors may affect its oral absorption and bioavailability. This study was aimed to conduct bioequivalence study for six commonly prescribed brands of atorvastatin. In this study in vitro bioavailability of six generic brands of atorvastatin were compared with the standard brand leader using their dissolution profiles and evaluation of pharmacokinetic data model independent approach (f1 and f2). Only one generic brand exhibits similar release profile and its f1 and f2 values were within range and the rest of the five brands did not show similar release patterns in comparison to the brand leader. The results of other physical test were found to be within range. It is concluded that all generic brands of atorvastatin are not bioequivalent in terms of their in vitro release behavior. Thus in vitro testing should be declared as mandatory requirement for registration of any pharmaceutical generic in Pakistan.