Analytical Review of Factors Influencing Bioavailability of Oral Drug Formulations Manufactured in Nigeria

The bioavailability of orally administered drugs is influenced by multiple formulation, manufacturing, and physiological factors, and systematic analytical review of bioavailability determinants for pharmaceutical products manufactured locally in Nigeria is absent from the literature. This study conducted an analytical review of factors influencing oral drug bioavailability with specific reference to locally manufactured Nigerian pharmaceutical products. A systematic analytical review of published dissolution testing data, comparative bioavailability studies, and regulatory submissions for locally manufactured oral formulations was conducted, drawing on NAFDAC regulatory documentation, peer-reviewed publications (2018 to 2024), and pharmaceutical industry technical reports. Nineteen drug classes marketed by 32 Nigerian pharmaceutical manufacturers were included. Analysis focused on dissolution profile quality, formulation excipient selection, manufacturing process variability, and post-marketing stability data. Results identified dissolution failure as the most common bioavailability-relevant quality concern, affecting 38.7 percent of reviewed solid oral formulations. Excipient-drug incompatibilities were identified in 24.3 percent of reviewed products. Stability data confirmed accelerated degradation under Nigerian tropical storage conditions in 31.2 percent of reviewed product dossiers. Generic-to-reference product dissolution dissimilarity was identified for critical-dose drugs in 22.6 percent of cases reviewed. The study provides the first comprehensive analytical synthesis of bioavailability determinants for locally manufactured oral products in Nigeria, identifying actionable improvements for manufacturers, regulators, and prescribers.

Keywords: bioavailability, oral drug formulations, local pharmaceutical manufacturing, Nigeria, dissolution testing