Modeling the Buy-back Contract in the Supply Chain of Pharmaceutical Aid by Considering the Investment in the Expired Drugs Reprocess

Every year, natural catastrophes like floods and earthquakes impact various regions, making the design of an efficient drug supply chain crucial for disaster preparedness. This study addresses this need by modeling supply chain decisions related to the storage and distribution of drugs before and after a crisis. It introduces an innovative approach by integrating a repurchase (Buy-Back) contract that includes reprocessing expired drugs, enhancing supply chain optimization under uncertainty. The study employs the Particle Swarm Optimization (PSO) algorithm, which effectively competes with exact methods, particularly in complex scenarios where traditional approaches may fail. This research not only provides a framework for optimizing the location of drug depots, resource allocation, and investment in reprocessing facilities but also offers actionable insights for enhancing disaster preparedness and response in pharmaceutical supply chains.