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Aprepitant/Fosaprepitant Injection

pronounced as (a pre' pi tant) (fos" a pre' pi tant)

Why is this medication prescribed?

Aprepitant injection and fosaprepitant injection are used along with other medications to prevent nausea and vomiting in adults that may occur within 24 hours or several days after receiving certain cancer chemotherapy treatments. Fosaprepitant injection can also be used in children 6 months of age and older. Aprepitant and fosaprepitant injections are not used to treat nausea and vomiting that you already have. 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 injection 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. For children and teenagers receiving aprepitant injection and adults receiving fosaprepitant with certain chemotherapy treatments, oral aprepitant may also be given on days 2 and 3 of the chemotherapy treatment cycle.

You may experience a reaction during or shortly after you receive a dose of aprepitant injection 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.

Ask your pharmacist or doctor for a copy of the manufacturer's information for the patient.

Other uses for this medicine

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 and pharmacist if you are allergic to fosaprepitant, aprepitant, any other medications, or any of the ingredients in aprepitant injection or fosaprepitant injection. Ask your pharmacist for a list of the ingredients.
  • 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.

What special dietary instructions should I follow?

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

What side effects can this medication 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 ( 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.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.

Brand names

  • Cinvanti®
  • Emend®
Last Revised - 11/15/2023