A drug used with other drugs to prevent nausea and vomiting caused by chemotherapy and nausea and vomiting after surgery. Aprepitant blocks the action of a certain chemical in the central nervous system that may trigger nausea and vomiting. Blocking this chemical may help lessen nausea and vomiting. Aprepitant is a type of antiemetic and a type of substance P/neurokinin 1 receptor antagonist. Also called Cinvanti and Emend.