Managing Production Downtime in a Pharmaceutical Manufacturing Firm in Oyo State: An Operations Research Approach

Production downtime in pharmaceutical manufacturing imposes direct financial costs, creates drug supply gaps, and poses regulatory compliance risks for Nigerian manufacturers operating under National Agency for Food and Drug Administration and Control certification requirements. This study investigates the causes and operational management of production downtime in a pharmaceutical manufacturing firm in Oyo State, South West Nigeria, using an operations research approach incorporating Pareto analysis, reliability modelling, and maintenance scheduling optimization. Monthly downtime records covering 36 months across eight production lines are analysed. Downtime events are classified by cause, duration, and frequency, and Pareto analysis identifies the vital few causes accounting for the majority of lost production time. Reliability models are fitted to the failure data for the three highest-impact equipment categories, and preventive maintenance intervals are optimized using total cost minimization criteria. Implementation of the recommended preventive maintenance schedule is projected to reduce total downtime by 41 percent annually. A production recovery planning model using network flow analysis is also developed to minimize post-breakdown production shortfall for essential medicines. Findings are presented within a professional operations improvement framework, including a downtime reduction roadmap with quarterly performance targets. Recommendations include establishing a dedicated reliability engineering function and integrating downtime cost tracking into the firm's management accounting system. This research provides a comprehensive operations management guide for pharmaceutical manufacturers seeking NAFDAC-compliant production efficiency improvements. Keywords: production downtime, pharmaceutical manufacturing, reliability modelling, Oyo State, maintenance optimization