Access to essential medications like metformin in Iran's healthcare system is significantly enhanced by preventing financial distress and ensuring robust cash flow through integrating quantity discounts and government subsidies. This study investigates their role in optimizing supply chain coordination, enhancing profitability, and reducing costs. By examining a two-tier pharmaceutical supply chain involving collaboration among government entities, pharmaceutical companies, and insurers under price controls, the research employs analytical models to assess their impact on stakeholder coordination and overall efficiency. The findings demonstrate that these strategies improve collaboration and optimize total supply chain profits. This study provides actionable insights into leveraging quantity discounts and government subsidies to strengthen coordination in Iran's pharmaceutical supply chain, ultimately ensuring equitable access to high-quality medications.