Isolation and Structural Characterization of Finasteride Degradation Products by Preparative HPLC, HRMS, and NMR

This study investigates the degradation profile of finasteride, a drug used for benign prostatic hyperplasia and androgenetic alopecia, under stress conditions. Using LC–MS, three degradation products were identified under acidic conditions, with minimal degradation in alkaline and oxidative environments. The degradation products were isolated and analyzed using preparative HPLC, HRMS, and NMR spectroscopy. The study revealed that the degradation process of DP-1 involved cleavage of the tert-butyl amide and addition of water across the alkene moiety. The structure of DP-1 was established through various spectroscopic techniques, and it, along with other degradation products, was found to be previously undescribed. These findings enhance the understanding of finasteride's degradation chemistry, aiding impurity profiling, stability studies, and quality control of its formulations.