Aprepitant Oral (Emend®); Fosaprepitant IV (Emend®); Aprepitant IV (Cinvanti®)

Author: Marisa Healy, BSN, RN
Last Reviewed: February 15, 2024

Pronounce: ap-RE-pi-tant; fos-a-PRE-pi-tant

Classification: Antiemetic, Substance P/Neurokinin 1 Receptor Antagonist

About: Aprepitant Oral (Emend®); Fosaprepitant IV (Emend®); Aprepitant IV (Cinvanti®)

This medication is a Substance P/Neurokinin 1 Receptor Antagonist. A protein called substance P transmits nerve messages from the gut to the vomiting center of the brain, also called the chemoreceptor trigger zone. Chemotherapy can cause substance P to activate neurokinin 1 receptors. This medication works to block the neurokinin 1 receptors to prevent both acute and delayed nausea and vomiting.

How to Take Aprepitant

The oral (taken by mouth) formulation of this medication, aprepitant (Emend®), can be taken with or without food. It is dosed daily for 3 days, beginning on the day of chemotherapy. The capsules should be swallowed whole. They should not be opened. Check to make sure you are taking the correct dose each day since they vary from Day 1 to Day 2.

The liquid suspension formulation is available and is made by mixing a powder version of the medication with water. This will be done by a healthcare provider. Your provider will tell you when to take this medication in relation to when you receive your chemotherapy. Check to make sure you are taking the correct dose each day since they vary from Day 1 to Day 2.

The intravenous (IV, into a vein) formulations of the medication should be given prior to the start of your chemotherapy. The IV formulation only needs one dose to work as compared to the oral formulations, which need to be given for multiple days.

Even when carefully and correctly administered by trained personnel, the IV formulation of this drug may cause a feeling of burning and pain. There is a risk that this medication may leak out of the vein at the injection site, causing tissue damage that can be severe. If the area of injection becomes red, swollen, or painful at anytime during or after the injection, tell your care team right away. Do not apply anything to the site unless told to do so by your care team.

Be sure to tell your healthcare provider about all medications and supplements you take. This medication can interfere with the blood levels of other medications including pimozole, ketoconazole, diltiazem, midazolam, rifampin, and paroxetine, among others. If you take warfarin this medication could interfere with your INR level. Your INR will be closely monitored while you are taking this medication. This medication can also interfere with hormonal forms of contraception. It is important to use a non-hormonal form of contraception while taking this medication and for 1 month after your last dose.

Storage and Handling

All oral versions of aprepitant should be stored in the original, labeled container at room temperature. Keep containers out of reach of children and pets.

Where do I get this medication?

The oral formulations of aprepitant are available through retail/mail order pharmacy. Your oncology team will work with your prescription drug plan to identify an in-network retail/mail order pharmacy for medication distribution. You can work with your doctor’s office if this medication needs a prior authorization.

Insurance Information

The oral versions of this medication may be covered under your prescription drug plan. Patient assistance may be available to qualifying individuals without prescription drug coverage. Co-pay cards, which reduce the patient co-pay responsibility for eligible commercially (non-government sponsored) insured patients, may also be available. Your care team can help you find these resources, if they are available. The IV formulations would be covered by your medical insurance.

Possible Side Effects of Aprepitant

This medication is given to manage and/or prevent side effects of your cancer treatment. If you are having side effects from this medication you should talk to your team about if this medication is necessary to your treatment or if there are other options to help manage the side effect this medication is treating. These are some of the most common side effects:


Fatigue is very common during cancer treatment and is an overwhelming feeling of exhaustion that is not usually relieved by rest. While on cancer treatment, and for some time after, you may need to change your schedule to manage fatigue. Plan times to rest during the day and save your energy for more important activities. Exercise can help fight fatigue. A simple daily walk with a friend can help. Talk to your healthcare team for helpful tips on dealing with this side effect.

Allergic Reactions

In some cases, patients can have an allergic reaction to this medication. Signs of a reaction can include: hives, rash, itching, skin peeling, sores, difficulty breathing, and difficulty swallowing. If you notice any changes in how you feel, let your nurse know immediately. If you are receiving the intravenous version of this medication the infusion will be slowed or stopped if this occurs.

Reproductive Concerns

Exposure of an unborn child to this medication could cause birth defects, so you should not become pregnant or father a child while on this medication. Hormonal birth control may not work as well while taking this medication. Effective non-hormonal birth control (for example condoms) should be used during treatment and for at least 1 month after treatment. Even if your menstrual cycle stops or you believe you are not producing sperm, you could still be fertile and conceive. You should consult with your healthcare team before breastfeeding while receiving this medication.