Near UV and visible light photo-degradation of therapeutic proteins: reaction mechanisms and significance for the development of pharmaceutical formulations

In the biotechnology industry, scientists are becoming increasingly aware that therapeutic protein formulations are susceptible to photo-degradation by near UV and/or visible light. Especially the reaction mechanisms leading to photo-degradation by visible light exposure are frequently unclear; however, progress in the characterization of a few of these processes has been made and this review summarizes reaction mechanisms which can rationalize some of the visible light-dependent photo-degradation in pharmaceutical formulations of therapeutic proteins. It will become clear that the mechanisms of photo-degradation do not necessarily depend only on the nature of the protein but also on the nature of excipients and common impurities.