Abstract
Background/Objectives: Lifitegrast is a recent therapeutic agent provoking scientific and regulatory interest due to its outstanding safety profile and high efficacy in the treatment of dry eye disease. Methods: Herein we employ NMR spectroscopy and mass spectrometry to investigate the weak spots of lifitegrast under standard to extreme stress conditions, resulting in the characterization of three known and nine new degradation products (of which DP7 presented the greatest structural challenge, but was eventually determined as C10 hydroxy derivative, warranting a revision of its previously suggested structure). Results: The first weak spot is identified as a N1-C40 amide bond, and its high susceptibility to hydrolysis is explained through computational DFT analysis. The second and third weak spots are elucidated through bond dissociation energy (BDE) calculations which highlighted the oxidative vulnerabilities of both the piperidine and benzofuran ring. Conclusions: Additionally, two degradation products, observed in initial, extended, and targeted oxidative forced degradation studies, were selected for in silico toxicity assessment and were predicted to have toxicity profiles comparable to or lower than lifitegrast.