Nowadays, retailers in the trade industry are focused on meeting customers’ needs, as their priority is to make as many sales per day as possible. Stockouts lead to unattended sales, which mean loss of income. This endangers the place of the MSBs in the industry. This paper aims to prove that proposing a supply management model will reduce the number of lost sales due to stockouts. For this study, we analyzed three key processes (purchasing, storage and distribution), where we identified problems such as incomplete shipments and unfulfilled POs and replacement requests. To prove the viability of our proposal, a pilot was carried out in a pharmacy that has five dispensing premises and a central warehouse, which improved its stock availability from 82% to 89.5%.