Neurokinin 1 is a G protein-coupled receptor found in the central nervous system and peripheral nervous system. The endogenous ligand for this receptor is substance P. It is found in high concentrations in the vomiting centre of the brain and produces a vomiting reflex when activated. Aprepitantis a neurokinin 1 (NK1) receptor antagonist. Aprepitant is indicated for prevention of acute and delayed
chemotherapy-induced nausea and vomiting. In clinical trials, it has been shown to be most effective for improving the anti-emetic response of the 5-HT3 receptor antagonist ondansetron and the corticosteroid dexamethasone for patients receiving highly emetogenic chemotherapy. Therefore, aprepitant is applied in combination with one of these drugs. The use of other drugs in combination with aprepitant should be checked carefully, since this drug is a substrate, inhibitor, and inducer of CYP3A4 and an inducer of CYP2C9. Adverse effects include hiccup, fatigue, elevated liver enzymes, and GI complaints.