A developed model and heuristic algorithm for inventory routing problem in a cold chain with pharmaceutical products

Inventory routing problem considers inventory allocation and routing problems simultaneously, in which the replenishment policies and routing arrangement are determined by the supplier under the vendor managed inventory mode. In this paper we study deterministic inventory routing problem in a pharmaceutical supply chain with a distributor and multiple geographically dispersed retailers. Two types of products are considered, first refrigerated which need temperature-controlled vehicles to be delivered and second non-refrigerated. Therefor our problem is defined in a cold chain which is a temperature-controlled supply chain. Vehicles capacity and holding capacity of retailers is consist of refrigerated and non-refrigerated parts. We propose a mixed integer linear programming (MILP) model. The objective is to minimize the sum of transportation and inventory costs. We also propose an adaptive large neighborhood search heuristic to solve the problem. In the initialization phase of the algorithm, a two phase heuristic algorithm is proposed. We used standard data sets to demonstrate the performance of the proposed algorithm.