Development and Validation of a Pharmacovigilance Framework for Herbal-Drug Interactions in Nigeria: A Multi-Zone Mixed-Methods Investigation

Background: The concurrent use of herbal medicines and conventional drugs is prevalent across all Nigerian geopolitical zones, yet a structured pharmacovigilance framework for detecting, assessing, and managing herbal-drug interactions does not currently exist within the national regulatory infrastructure. This research aims to develop and validate such a framework using evidence generated from multi-zone field investigations. Methods: A sequential mixed-methods design spanning three phases will be employed. Phase one involves ethnopharmacological surveys across six geopolitical zones to identify the most commonly co-used herbal and conventional drug combinations (n = 1,200 patients). Phase two employs in vitro cytochrome P450 interaction studies and pharmacokinetic profiling of the top ten identified combinations. Phase three uses a consensus-based modified Delphi technique with regulatory, clinical, and academic experts (n = 45) to validate the proposed framework components. Results: Preliminary ethnopharmacological data from pilot sites reveal concurrent herbal-conventional drug use in 63 percent of patients. CYP3A4 and CYP2D6 inhibition potential has been identified in four commonly used herbal preparations. Delphi consensus on framework domains is currently underway. Conclusion: This research will produce a contextually grounded, scientifically validated pharmacovigilance framework for herbal-drug interactions in Nigeria, contributing a novel regulatory tool to national medicines safety governance. Keywords: pharmacovigilance, herbal-drug interactions, Nigeria, cytochrome P450, regulatory framework