Last reviewed 2026-04-20 · How we verify

Emend (APREPITANT)

Emend works by blocking the action of a natural substance called substance P, which is involved in the vomiting reflex.

Emend (Aprepitant) is a small molecule substance P/neurokinin-1 receptor antagonist developed by Merck and currently owned by MSD Merck Co. It targets the substance P receptor to prevent nausea and vomiting caused by chemotherapy and post-operative procedures. Emend was FDA-approved in 2003 for these indications and has since become available as a generic medication. The drug has a half-life of 13 hours and bioavailability of 62%. It is used in combination with other antiemetics to provide effective control of nausea and vomiting.

At a glance

Mechanism of action

Aprepitant is selective high-affinity antagonist of human substance P/neurokinin (NK1) receptors. Aprepitant has little or no affinity for serotonin (5-HT3), dopamine, and corticosteroid receptors, the targets of existing therapies for chemotherapy-induced nausea and vomiting (CINV).Aprepitant has been shown in animal models to inhibit emesis induced by cytotoxic chemotherapeutic agents, such as cisplatin, via central actions. Animal and human Positron Emission Tomography (PET) studies with aprepitant have shown that it crosses the blood brain barrier and occupies brain NK1 receptors. Animal and human studies show that aprepitant augments the antiemetic activity of the 5-HT3-receptor antagonist ondansetron and the corticosteroid dexamethasone and inhibits both the acute and delayed phases of cisplatin-induced emesis.

Approved indications

• Chemotherapy-induced nausea and vomiting
• Prevention of Post-Operative Nausea and Vomiting

Common side effects

• Asthenia/Fatigue
• Nausea
• Dehydration
• Dizziness
• Abdominal Pain
• Fever
• Mucous Membrane Disorder
• Headache
• Insomnia
• Hiccups
• Neutropenia
• Anorexia

Drug interactions

• CYP2C9 Substrates
• alfentanil
• astemizole
• carbamazepine
• cisapride
• desogestrel
• dexamethasone
• ethinylestradiol
• fosphenytoin
• levonorgestrel
• methylprednisolone
• norethisterone

Key clinical trials

• Pilot Study of Aprepitant Effect on Aldosterone Secretion in Diabetic Patient (Diabetes Mellitus) With Hypertension Associated With Low Renin (PHASE2)
• Mechanisms Underlying Hypotensive Response to ARB/NEP Inhibition - Aim 3 (PHASE4)
• Personalized Antiemetic Regimen According to Patients' Pharmacogenetic Profile (PHASE2)
• Adding Aprepitant to a Multimodal Strategy for the Prevention of Postoperative Nausea and Vomiting in High-risk Outpatient Surgical Patients (PHASE3)
• Phase 2 Bunionectomy HTX-011 Administration Study (PHASE2)
• Aprepitant Injectable Emulsion in Patients With COVID-19 (GUARDS-1) (PHASE2)
• Effect of Aprepitant on Post-operative Nausea and Vomiting in Otologic Surgery (PHASE4)
• 5-Azacytidine and/or Nivolumab in Resectable HPV-Associated HNSCC (PHASE2)

Patents

Primary sources

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