Safinamide-d 4 -1 is deuterium labeled Safinamide. Safinamide is a potent, selective, and reversible monoamine oxidase B ( MAO-B ) inhibitor (IC50=0.098 µM) over MAO-A (IC50=580 µM). Safinamide also blocks sodium channels and modulates glutamate (Glu) release, showing a greater affinity at depolarized (IC50=8 µM) than at resting (IC50=262 µM) potentials. Safinamide has neuroprotective and neurorescuing effects and can be used for the study of parkinson disease, ischemia stroke etc.al.