Fosaprepitant-d 4 (dimeglumine) is deuterium labeled Fosaprepitant (dimeglumine). Fosaprepitant dimeglumine (MK-0517) is a proagent of Aprepitant. Fosaprepitant dimeglumine is a neurokinin-1 receptor antagonist, which is development for the prevention of chemotherapy-induced nausea and vomiting (CINV).