Therapeutic apartheid: a cross-sectional assessment of estimated cost, accessibility, affordability, and availability among psychotropic medications across 25 regions.

INTRODUCTION: Mental disorders affect approximately 20% of the global population and remain a leading cause of disability and premature mortality. Despite pharmacotherapy being central to treatment, access to psychotropic medicines is highly unequal, particularly in low- and middle-income countries. In South America, comprehensive national evaluations integrating availability, price, affordability, and geographic accessibility are scarce. OBJECTIVE: To assess the availability, cost, affordability, and geographic accessibility of psychotropic medicines across public and private sectors in all regions of Peru. DESIGN: A secondary cross-sectional analytical study. METHODS: We use open-access data from the Peruvian Observatory of Pharmaceutical Products between May 20 and 25, 2025. A total of 54 psychotropic medicines were included based on the WHO and national essential medicine lists and expert consensus. Outcomes included median unit cost (interquartile range), availability (% of facilities), affordability (days of minimum wage for a 30-day treatment), and regional accessibility. Public-private cost differences were assessed using Wilcoxon rank-sum tests and Cliff's Delta. RESULTS: Only 22.2% of psychotropics were classified as essential by both WHO and national criteria. Median costs were substantially higher in the private sector, with price differences ranging from 2- to 140-fold (e.g., risperidone 2 mg: $1.41 private vs $0.01 public; Cliff's Delta = 0.99). While essential medicines were generally affordable in the public sector (<1 day of minimum wage), newer and long-acting formulations required up to 276 days of labor. Public-sector availability was limited, and geographic accessibility showed marked centralization: several Amazonian and highland regions lacked access to key psychotropics, whereas private-sector availability was near-universal. CONCLUSION: Psychotropic medication access in Peru is characterized by profound economic and geographic inequities. TRIAL REGISTRATION: Not applicable.