Challenges and Proposed Solutions for Optimizing the Pharmaceutical Supply Chain Using the WHO Health System Building Blocks Framework: A Systematic Review.

Background: Equitable access to medicines is a cornerstone of the health system and is essential for achieving universal coverage. The pharmaceutical supply chain faces challenges that lead to drug shortages and disruptions in service delivery. This study aimed to identify challenges and effective solutions for optimizing the pharmaceutical supply chain. Methods: This systematic review was conducted in 2025 in accordance with a predefined protocol and the PRISMA guidelines. Web of Science, Scopus, PubMed, and Embase were searched up to October 25, 2025, supplemented by a search of grey literature through Google Scholar. Studies addressing challenges or optimization strategies related to pharmaceutical supply chains were included. Methodological quality was independently assessed using the CASP, JBI, and MMAT appraisal tools according to study design. Data were synthesized using the WHO Health System Building Blocks framework. Results: A total of 23,110 studies were identified, of which 30 met the inclusion criteria. The included studies were conducted across 16 countries, reflecting a geographically diverse and internationally representative evidence base. Frequently reported challenges included weak governance and supervision, insufficient financial resources, shortages of raw materials and dependence on foreign markets, inadequate forecasting and planning, and weaknesses in pharmaceutical production and distribution systems. The most proposed optimization strategies included strengthening policymaking and centralized monitoring, enhancing intersectoral collaboration, investing in digital information systems and demand forecasting, supporting domestic production capacity, and ensuring sustainable financing to prevent medicine shortages and improve supply chain resilience. Conclusion: Evidence suggests that strengthening governance structures, improving inter-sectoral coordination, and increasing transparency and accountability are key prerequisites for optimizing pharmaceutical supply chains. Financial stability, developing domestic production capacity, and strategic investments in human resources further contribute to supply chain resilience. These findings highlight the need for policymakers to prioritize governance reforms, sustainable financing strategies, domestic manufacturing capacity, and digital supply chain systems to improve medicine availability and reduce the risk of drug shortages.