PHOTODEGRADATION OF ACTIVE INGREDIENTS AN D CURRENT METHODS FOR ITS ANALYTICAL INVESTIGATION

Photostability testing is an essential part of the stability testing p rogram for drug substances. In contrary to the thermal stability until now there are no internationally fixed testing conditions for the pho tostability testing. In order to obtain reproducible results, artifici al light sources with a defined light intensity and exposure time shou ld be used for the light exposure. The investigation of samples after light exposure must be performed with suitable analytical testing meth ods. Spectrophotometry can be used for preliminary studies. High perfo rmance liquid chromatography is the routine method for quantitative an alysis in stability testing. The coupling of chromatography and spectr oscopy is a new mean of getting more information about photodegradatio n processes. Since LC-MS using a particle beam interface provides eith er EI or CI spectra, it is especially well suited for the detection of the degradation pathways.