title: A novel approach for inventory problem in the pharmaceutical supply chain.
abstract: BACKGROUND
  In pharmaceutical enterprises, keeping up with global market conditions is possible with properly selected supply chain management policies. Generally; demand-driven classical supply chain model is used in the pharmaceutical industry. In this study, a new mathematical model is developed to solve an inventory problem in the pharmaceutical supply chain.
  
  
  METHODS
  Unlike the studies in literature, the "shelf life and product transition times" constraints are considered, simultaneously, first time in the pharmaceutical production inventory problem. The problem is formulated as a mixed-integer linear programming (MILP) model with a hybrid time representation. The objective is to maximize total net profit. Effectiveness of the proposed model is illustrated considering a classical and a vendor managed inventory (VMI) supply chain on an experimental study.
  
  
  RESULTS
  To show the effectiveness of the model, an experimental study is performed; which contains 2 different supply chain policy (Classical and VMI), 24 and 30 months planning horizon, 10 and 15 different cephalosporin products. Finally the mathematical model is compared to another model in literature and the results show that proposed model is superior.
  
  
  CONCLUSIONS
  This study suggest a novel approach for solving pharmaceutical inventory problem. The developed model is maximizing total net profit while determining optimal production plan under shelf life and product transition constraints in the pharmaceutical industry. And we believe that the proposed model is much more closed to real life unlike the other studies in literature.
authors.affiliation: Industrial Engineering Department, Sakarya University, 54187, Sakarya, Turkey. gcandan@sakarya.edu.tr.
authors.forename: Gökçe
authors.initials: G
authors.lastname: Candan
authors.affiliation: Industrial Engineering Department, Sakarya University, 54187, Sakarya, Turkey. yazgan@sakarya.edu.tr.
authors.forename: Harun Reşit
authors.initials: HR
authors.lastname: Yazgan
mesh_terms: D004345:Drug Industry / Q000379:methods*; D008962:Models, Theoretical; D009716:Numerical Analysis, Computer-Assisted; D010934:Planning Techniques; D011382:Programming, Linear