LC/MS/MS study for identification of entacapone degradation product obtained by photodegradation kinetics

Entacapone is indicated for clinical use as an adjunct to levodopalcarbidopa to treat patients with idiopathic Parkinson's Disease who experience the signs and symptoms of end-of-dose wearing-off. The aim of this study was to determine the photodegradation kinetics and to elucidate the structure of the main degradation product. The stability of entacapone was studied in order to investigate the degradation kinetics of this drug using LC as a stability indicator. Entacapone was subjected to accelerated photodegradation. This study was carried out with methanolic solutions, prepared from coated tablets, in quartz cells under UV light at 254 nm. The degradation process of entacapone in solutions can be described by second-order kinetics under the experimental conditions used in this study. The LC/MS/MS determinations revealed that in the above conditions the photodegraded product formed the geometric isomer of entacapone (Z-entacapone). The obtained results show the importance of appropriate light protection during the drug development process, storage, and handling.