Liquid chromatographic analysis of ethacrynic acid and degradation products in pharmaceutical systems.

An accurate, reproducible, and specific reversed-phase high-performance liquid chromatographic (HPLC) system was developed for the determination of ethacrynic acid and its degradation products. The method was used in stability studies of the drug in the solid state, in solution, and in dosage forms. Three degradation products were isolated by preparative chromatography and identified by several techniques, principally NMR and MS. TLC Rt and HPLC response factors are quoted. A degradation scheme consistent with the observed stability profiles is proposed.