Despite the increasing importance of inventories in terms of cost and business competitiveness, inventory replenishment policies have received little or no attention from hospitals in Ecuador, which despite having, in some cases, sophisticated computer systems to manage the replenishment of medicines, still use simple rules to parameterize them or simply rely on the experience of the buyers. This has led to scenarios of excess inventory, obsolescence, and in other cases, a low availability of essential medicines for patients. The present research shows how through 1) reduction of controllable variability, 2) stratification of the inventory, 3) improvement of forecasts accuracy, 4) implementation of replenishment policies based on optimization models, and 5) Staff training, was possible to reduce the pharmacy inventory costs in a local hospital by 27.14% while improving the level of shelf availability of medicines by 8%, measured three months after inventory policies implementation.