Comparative in vitro bioequivalence evaluation of atenolol tablets available in Sri Lanka

Abstract

Abstract: The availability of multiple brands for a single drug places health professionals and patients in a dilemma of drug substitution. Hence, evaluating bioequivalence of different brands compared to respective innovator drug is a timely need. This study was performed to compare the in vitro bioequivalence of commercially available brands of atenolol 50 mg tablets in the Sri Lankan market. Four different brands of atenolol 50 mg tablets (A1 – A4) and the innovator drug (A5) were selected for the study. All the tablets were tested for organoleptic properties, uniformity of weight, thickness and diameter, hardness, friability, assay percentage and dissolution. To evaluate in vitro bioequivalence of the selected drugs, their dissolution profiles were compared with the innovator drug using calculated fit factors (difference and similarity factors) and dissolution efficiencies of respective brands. The results of organoleptic properties of all the tested tablets showed no sign of defects. Tablets’ thickness, diameter and hardness complied with the general standards. All the tested tablets complied with the British Pharmacopoeial (BP) standards for uniformity of weight, friability, assay percentage and dissolution. Tablets; A1-A4 had similarity factors above 50 and the difference factors below 15 revealing that their dissolution profiles are similar to the innovator product. According to the dissolution efficiency calculations, only A1, A2, and A3 of the selected brands of atenolol 50 mg tablets were similar with the innovator. Hence, the brands; A1, A2 and A3 could be regarded as bioequivalent thus expected to produce similar therapeutic effects.