Recycling of active pharmaceutical ingredients Metformin hydrochloride and Losartan potassium from expired medications and crystal structure of a new Losartan polymorphic form.

Abstract

The disposal of expired pharmaceutical tablets, particularly those from household sources, is a growing environmental concern due to the accumulation of pharmaceutical contaminants in water ecosystems. Despite FDA recommendations to discard expired medications, studies have shown that many of these pills retain up to 90 % of their original potency long after their expiration date. This opens up the possibility for recycling and reusing the Active Pharmaceutical Ingredients (APIs) contained in these expired pills. This study presents a simple yet effective extraction protocol for recovering APIs from expired tablets of Metformin hydrochloride and Losartan potassium. The method achieved recovery yields of 88 % for Losartan and 37 % for Metformin. Structural characterization via NMR, HPLC, IR, HRMS, and both powder, and single-crystal X-ray diffraction confirmed the integrity and high purity of the recovered APIs compared to chemical standards. Biological assays carried out in L929 cell line revealed that the extracted APIs retained comparable activity to their chemical-standard counterparts, suggesting their potential for reuse in biochemical assays. During the recrystallization process by using PDRX, a new polymorphic form of Losartan potassium was discovered and named "Form M". In addition, a twelve-month stability study showed no degradation for either API at storage conditions. These results suggest that expired APIs are chemically and biologically viable for repurposing, as synthetic precursors in chemical research and in biological assays. The protocol is scalable, adaptable to pharmaceutical companies, and applicable in both industrial and research settings, offering a sustainable solution to pharmaceutical waste. By recovering APIs for educational and industrial use, this approach promotes environmental stewardship and resource efficiency in pharmaceutical science.