Part II: Forced Degradation Studies to Support Photostability
In Part One of this photostability blog series, a high level review on the background of photostability was presented. In this second part, work leading up to the execution of a photostability study on Active Pharmaceutical Ingredient (API) and pharmaceutical products will be discussed.
Prior to execution of a photostability study, the analytical test procedures (TP) must demonstrate the ability to detect degradants caused by photolysis (photodegradation). Not all compounds are susceptible to photolysis; a molecule must absorb the UV or visible light energy to be susceptible to this phenomenon. For example, if the absorption spectrum of a molecule has a maximum of ~254 nm and with minimal or no absorption above 300 nm, this molecule would not be susceptible to photodegradation during an ICH photostability study as the lowest wavelength of exposure is ~320 nm.