COMPARATIVE IN VITRO EVALUATION OF DIFFERENT BRANDS OF NIFEDIPINE 20mg RETARD TABLET PRODUCTS MARKETED IN ADDIS ABABA, ETHIOPIA

Abstract

Nifedipine has been formulated and marketed as extended-release-film coated tablet. A certain degree of success has been achieved in reducing the incidence of adverse effects by the use of slow-release formulations such as nifedipine retard. The aim of the present study was to evaluate the physicochemical quality attributes and in vitro equivalence of six brands of nifedipine retard tablets available in different retail outlets in Addis Ababa, Ethiopia. After constructing the calibration curve, the in vitro drug release studies were carried out using USP type I dissolution apparatus at 100 rpm. The dissolution was done in a medium of 0.1N HCl containing 0.5% sodium lauryl sulfate for 12 hrs. All the tablets met the requirement for tablet weight uniformity. The mean crushing strengths of sample tablets ranged from 49.2 to 111.2 N. All the brands studied released more than 80% within 12 hours which is within the tolerance limit.  However the release profile revealed that five of the brands showed over 15% drug release at 1st hour except product F which released only 14.32%. In conclusion, all the brands of tablets had uniform thickness and good hardness. Despite all the brands could sustained the release for over 12 hours recommended for such formulations, five of them showed higher release in the first hour which may affect their in vivo performance.” Keywords: nifedipine, retard tablets, physicochemical properties, crushing strengths, in vitro drug release