Developing an Original Biopharmaceutical Classification and In Vitro-In Vivo Correlation Framework for Locally Manufactured Nigerian Pharmaceuticals

The Biopharmaceutics Classification System provides a regulatory framework for predicting oral drug absorption, yet its application to locally manufactured Nigerian pharmaceuticals, which exhibit distinct formulation characteristics and are produced under tropical conditions, has not been systematically investigated. This study developed an original biopharmaceutical classification and in vitro-in vivo correlation (IVIVC) framework specifically applicable to locally manufactured solid oral pharmaceutical products in Nigeria. A systematic methodology encompassing solubility classification, dissolution method development, and IVIVC model construction was employed across 25 selected drug products manufactured by five Nigerian pharmaceutical companies. Aqueous solubility was determined in biorelevant media (FaSSIF, FeSSIF). Dissolution profiles were generated using USP Apparatus II with six dissolution media and validated against the BCS classification criteria. In vivo pharmacokinetic data were obtained from bioequivalence studies conducted in compliance with NAFDAC registration requirements. IVIVC models were developed using the convolution approach in Phoenix WinNonlin. Results classified 44.0 percent of products as BCS Class I, 28.0 percent as Class II, and 28.0 percent as Classes III and IV. IVIVC Level A correlations were established for 8 of 12 BCS Class II products. Formulation-related IVIVC failures were characterised for six products, with dissolution-limited absorption attributed to excipient incompatibilities and particle size variability. The framework provides an original contribution to biopharmaceutics science applicable to Nigerian product development and regulatory science.

Keywords: biopharmaceutics classification system, IVIVC, local pharmaceutical manufacturing, Nigeria, drug absorption