OBJECTIVES: This paper aims to develop a robust optimization approach combining mathematical programming and discrete event simulation (DES) model as evaluation for the hospital to determine future optimized factors and hospital drugs distribution system (HDDS) scenario to inpatient to avoid stock out and ensure the punctuality of clinical treatments.

METHODS: This research analyzed the application of DES as a methodology to model the complex drug distribution system from hospital pharmacy to inpatient under well-defined conditions to evaluate the current drug distribution system from hospital pharmacy to inpatient group and to show potential areas for improvement.

RESULTS: The study shows that the best solution is to combine the route optimization and the stock management using scenario 2 (The ordering process is done if the stock of drugs in the nurse ward has reached a certain number, so that in each nurse ward has a medication stock of at least as much as the average demand for each type of drug package), which can reduce patient waiting time become 80.85 minutes, based on the current system 130.47 minutes (reduce 49.62 minutes overall).

CONCLUSIONS: This research has presented a model of drugs distribution system to see availability, quality, and time accuracy of drug delivered to inpatient in the hospital using Discrete Event Simulation (DES), as a model simulation-based tool to determine the efficient resources and scheduling time in ordering drugs stock and distribution process in correct time, place, quantity-based on current situation and simulate possible solution scenarios for future planning in drug distribution process. DES model accurately captures the variations in the system and it is flexible to simulate drug distribution scenarios allowing the improvement of the healthcare supply chain flexibility and performance.