New inventory model for perishable valuable materials such as special diseases' drugs

Inventory control models for perishable materials of different industries especially chemical, food and medicinal industries are very sensitive. Since drugs ingredients are mostly organic compounds and effective application of them in medications depend on appropriate stability level, the way drug compounds decayed follow chemical stability functions. In this research, at first, the drug products deteriorate function is studied and then an inventory model for medicinal products with drug deteriorate function is presented in order to obtain the least cost considering shortage of backlogging. Demand rate depending on inventory level is modeled in three levels: one producer, two distributors and six buyers. Finally, optimum of drug supply chain model costs is studied and compared in two modes of integrated and non-integrated.