Pharmaceutical registration, essential medicines, and registration depth in Sri Lanka: a longitudinal analysis, 1991–2025

Pharmaceutical registration determines which medicines may enter the market, yet its role in shaping pharmaceutical market structure in relation to essential medicines has received limited attention, particularly in low- and middle-income countries. This study examined how pharmaceutical registration portfolios in Sri Lanka evolved in relation to essential medicines alignment, therapeutic composition, and sources of supply. Pharmaceutical registrations were analysed in Sri Lanka at three time points (1991, 2009, and 2025) to examine changes in the structure of the registration portfolio and alignment with the Essential Medicines List (EML) at both product and active substance levels. Data for 1991 were derived from a published study, while analyses were conducted for 2009 and 2025 using national registration records. The number of registered products increased substantially between 1991 and 2009 and remained high in 2025, while the number of active substances changed modestly. Product-level alignment with the EML declined from 71.0% in 1991 to 38.0% in 2025, whereas active-substance-level alignment increased from 31.4% to 59.4%. This divergence reflected broader coverage of essential active substances alongside fewer products per substance. The composition of the register shifted, with a declining share of anti-infective medicines and increasing representation of medicines for chronic conditions. The registration portfolio remained import dependent, although the proportion of locally manufactured substances increased between 2009 and 2025. Registration depth among active substances was uneven, with many substances represented by few or no registered products. Pharmaceutical registration in Sri Lanka remained broadly aligned with essential medicines priorities over time, but this alignment occurred through changing portfolio structures. The study shows that assessments based on the number of registered products may not capture therapeutic breadth at the active-substance level. The findings highlight the importance of considering registration depth and import dependence when interpreting pharmaceutical market structure and supply vulnerabilities in import-dependent health systems.