Quality assessment and in vitro bioequivalence studies of chlorpheniramine maleate tablets marketed within Zaria metropolis, Kaduna State, Nigeria

Abstract

Chlorpheniramine maleate is a widely used over-the-counter antihistamine for the relief of allergy and cold symptoms. This study evaluated the bioequivalence of ten chlorpheniramine maleate tablet samples (coded A–J) compared with the innovator brand. Pharmacopeial methods (BP/USP 2009) were applied to assess physicochemical properties, while three UV-spectrophotometric methods were developed and validated in line with ICH Q2 (2022) guidelines to determine drug release in simulated physiological media (pH 1.2, 4.5, and 6.8). In vitro dissolution testing was performed using USP Apparatus II at 37 ± 0.5°C and 100 rpm across the three pH media, with samples collected at intervals up to 60 minutes. Dissolution profiles were analyzed using difference (f₁) and similarity (f₂) factors, as well as dissolution efficiency (% DE). All samples passed the identification test. However, sample G failed the friability test, and sample D failed both disintegration and dissolution requirements. Generics B, F, and H met acceptable f₁ and f₂ limits in all media. samples C, E, G, J, and I showed equivalence in one or two media, while D failed in all. All samples had % DE values within ±10% of the reference. In conclusion, only B, F, and H were bioequivalent and interchangeable.