Class Name(s):

• 56:22.32 Neurokinin-1 Receptor Antagonists

Pronunciation:

• (a pre' pi tant) (fos" a pre' pi tant)

Brand Name(s):

• Cinvanti^®
• Emend^®; also available generically

WHY is this medicine prescribed?

Aprepitant injection and fosaprepitant injection are used to prevent nausea and vomiting. Aprepitant and fosaprepitant injections are in a class of medications called antiemetics. They work by blocking the action of neurokinin, a natural substance in the brain that causes nausea and vomiting.

HOW should this medicine be used?

Aprepitant injection comes as an emulsion (liquid) and fosaprepitant injection comes as a powder to be mixed with liquid and given intravenously (into a vein) by a doctor or nurse in a medical facility. Aprepitant or fosaprepitant injection is usually given as a one-time dose on day 1 of a chemotherapy treatment cycle, finishing about 30 minutes before the start of chemotherapy.

Are there OTHER USES for this medication?

This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.

What SPECIAL PRECAUTIONS should I follow?

Before using aprepitant or fosaprepitant injection,

• tell your doctor or pharmacist if you are allergic to this medication, any part of this medication, or any other medications, foods or substances. Tell your doctor or pharmacist about the allergy and what symptoms you had.
• some medications should not be taken with aprepitant or fosaprepitant injection. Other medications may cause dosing changes or extra monitoring when taken with aprepitant or fosaprepitant injection. Make sure you have discussed any medications you are currently taking or plan to take before receiving aprepitant or fosaprepitant injection with your doctor and pharmacist. Before starting, stopping, or changing any medications while receiving aprepitant or fosaprepitant injection, please get the advice of your doctor or pharmacist.
• tell your doctor if you have or have ever had liver disease.
• tell your doctor if you are pregnant, plan to become pregnant, or are breastfeeding. If you are using hormonal contraceptives (birth control pills, patches, rings, implants, or injections) during treatment with aprepitant or fosaprepitant you should also use an additional nonhormonal method of birth control (spermicide, condom) to avoid pregnancy during treatment with aprepitant or fosaprepitant and for 1 month after your final dose. Talk to your doctor about birth control methods that will work for you. If you become pregnant while using aprepitant or fosaprepitant injection, call your doctor.
• you may experience a reaction during or shortly after you receive a dose of aprepitant or fosaprepitant injection. Tell your doctor immediately if you experience any of these symptoms during or shortly after you receive treatment: swelling around your eyes, rash, hives, itching, redness, flushing, difficulty breathing or swallowing, feeling dizzy or faint, or fast or weak heartbeat. Your doctor will probably stop the infusion, and may treat the reaction with other medications.

What SPECIAL DIETARY instructions should I follow?

Unless your doctor tells you otherwise, continue your normal diet.

What SIDE EFFECTS can this medicine cause?

Aprepitant injection and fosaprepitant injection may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

• tiredness or weakness
• diarrhea
• pain, redness, itching, hardness, or swelling at the injection site
• weakness, numbness, tingling, or pain in arms or legs
• headache
• heartburn

Some side effects can be serious. If you experience any of these symptoms, call your doctor immediately:

• peeling or blistering of the skin
• frequent or painful urination, sudden need to urinate right away

Aprepitant and fosaprepitant may cause other side effects. Call your doctor if you have any unusual problems while using this medication.

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online (http://www.fda.gov/Safety/MedWatch) or by phone (1-800-332-1088).

What OTHER INFORMATION should I know?

Keep all appointments with your doctor.

Do not let anyone else use your medication. Ask your pharmacist any questions you have about refilling your prescription.

Keep a written list of all of the prescription and nonprescription (over-the-counter) medicines, vitamins, minerals, and dietary supplements you are taking. Bring this list with you each time you visit a doctor or if you are admitted to the hospital. You should carry the list with you in case of emergencies.

This report on medications is for your information only, and is not considered individual patient advice. Because of the changing nature of drug information, please consult your physician or pharmacist about specific clinical use.

The American Society of Health-System Pharmacists, Inc. represents that the information provided hereunder was formulated with a reasonable standard of care, and in conformity with professional standards in the field. The American Society of Health-System Pharmacists, Inc. makes no representations or warranties, express or implied, including, but not limited to, any implied warranty of merchantability and/or fitness for a particular purpose, with respect to such information and specifically disclaims all such warranties. Users are advised that decisions regarding drug therapy are complex medical decisions requiring the independent, informed decision of an appropriate health care professional, and the information is provided for informational purposes only. The entire monograph for a drug should be reviewed for a thorough understanding of the drug's actions, uses and side effects. The American Society of Health-System Pharmacists, Inc. does not endorse or recommend the use of any drug. The information is not a substitute for medical care.

AHFS^® Patient Medication Information™ Copyright, 2026. The American Society of Health-System Pharmacists^®, 4500 East-West Highway, Suite 900, Bethesda, Maryland. All Rights Reserved. Duplication for commercial use must be authorized by ASHP.

Selected Revisions: October 15, 2026.