Successful characterization of degradation products of drugs using LC-MS tools: Application to piroxicam and meloxicam

The degradation behavior of piroxicam and meloxicam was studied by subjecting the drugs individually to hydrolytic (acidic, basic and neutral), oxidative, photolytic and thermal stress. Both the drugs showed significant degradation in hydrolytic, oxidative and photo-neutral conditions, while they were stable under dry heat and on exposure to light in the solid state. In total, five and four degradation products were formed from piroxicam and meloxicam, respectively. For characterization of the degradation products, mass fragmentation pathways of both the drugs were established with the help of MS/TOF, MSn and H/D exchange mass studies, followed by LC-MS/TOF and on-line H/D exchange experiments on the degradation products. The collected data helped to identify the degradation products of both the drugs. Eventually, degradation pathways were established, along with proposition of mechanisms for the formation of the degradation products.