The use of HPLC/MS, GC/MS, NMR, UV and IR to identify a degradation product of eperisone hydrochloride in the tablets.

Understanding drug degradation in the pharmaceutical dosage forms is critical as it has significant impacts on drug efficacy, safety profile and storage conditions. In this study, analytical techniques, such as high-performance liquid chromatograph mass spectrometry (HPLC/MS), gas chromatograph mass spectrometry (GC/MS) and nuclear magnetic resonance (NMR) had been applied to the identification of a drug degradation product which grew over time in the stability study of eperisone hydrochloride tablets. The target unknown degradation product is ionizable by atmospheric pressure chemical ionization (APCI) in a positive mode to determine its relative molecular weight. GC/MS with electron impact ionization (EI) was employed to determine the fragmentation pattern of this unknown compound. Structure elucidation of eperisone and its unknown degradation product by spectral data had been discussed in detail. The isolated unknown was analyzed by NMR, UV and IR, from which the structure of the degradation product was further confirmed as 1-(4-ethylphenyl)-2-methyl-2-propen-1-one.