Aprepitant belongs to the class of medications called neurokinin 1 (NK1) receptor antagonists. It is used along with medications called 5-HT3 antagonists (such as ondansetron and granisetron) and dexamethasone to prevent nausea and vomiting caused by certain types of chemotherapy. It works by blocking neurokinin, a substance in the brain that causes nausea and vomiting.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

The recommended dose of aprepitant is 125 mg taken by mouth, 1 hour before chemotherapy and 80 mg once daily in the morning for the next 2 days following chemotherapy.

Aprepitant can be taken with or without food. It should not be taken for longer than 3 consecutive days during each cycle of chemotherapy.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important that this medication be taken exactly as prescribed by your doctor. If you miss a dose, contact your doctor for advice.

Store this medication at room temperature and keep it out of the reach of children.

Capsules

80 mg
Each white, opaque hard gelatin capsule with "461" and "80 mg" printed radially in black ink, contains 80 mg of aprepitant. Nonmedicinal ingredients: hydroxypropyl cellulose, microcrystalline cellulose, sodium lauryl sulfate, and sucrose; capsule shell: gelatin and titanium dioxide.

125 mg
Each opaque, hard gelatin capsule with white body and pink cap with "462" and "125 mg" printed radially in black ink, contains 125 mg of aprepitant. Nonmedicinal ingredients: hydroxypropyl cellulose, microcrystalline cellulose, sodium lauryl sulfate, and sucrose; capsule shell: gelatin, red ferric oxide, titanium dioxide, and yellow ferric oxide.

Tri-pack

The package contains two 80 mg capsules and one 125 mg capsule.

Do not take aprepitant if you:

• are allergic to aprepitant or to any of the ingredients of the medication
• are also taking any of the following medications: pimozide, terfenadine, astemizole, or cisapride

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• abdominal pain
• changed sense of taste
• constipation
• diarrhea
• dizziness
• dry mouth
• fatigue
• flushing
• hair loss
• headache
• hiccups
• loss of appetite
• muscle cramps
• upset stomach
• vomiting
• weakness

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor immediately if any of the following side effects occur:

• anxiousness
• fever
• low blood pressure
• increased sweating
• painful, burning urination
• red, itchy eyes with discharge
• ringing in the ears
• signs of infection (symptoms may include fever or chills, severe diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, weight loss, or listlessness)

Stop taking the medication and seek immediate medical attention if any of the following occur:

• severe rash, itching, or swelling of the hands and feet
• signs of a severe skin reaction such as blistering, peeling, a rash covering a large area of the body, a rash that spreads quickly, or a rash combined with fever or discomfort
• symptoms of a severe allergic reaction (e.g., difficulty breathing; hives; swelling of the face, eyes, lips, tongue, or throat)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Birth control: This medication may reduce the effectiveness of hormonal birth control pills during aprepitant treatment, and for 28 days after treatment. Use another (or backup) method of birth control during treatment and for 1 month following the last dose of aprepitant.

Other medications: Aprepitant may cause many drug interactions, especially with medications that are broken down mainly through the liver and with a blood thinner called warfarin (see "What medications can interact with this medication?"). Your doctor will monitor you closely if you are taking any of these medications.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: It is not known if aprepitant passes into breast milk. If you are a breast-feeding mother and are taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using this medication have not been established for children less than 18 years of age.

There may be an interaction between aprepitant and any of the following:

• alpha blockers (e.g., alfuzosin, doxazosin, tamsulosin)
• amiodarone
• anti-cancer medications (e.g., cabazitaxel, docetaxel, doxorubicin, etoposide, ifosfamide, irinotecan, vincristine)
• anti-psychotics (e.g., aripiprazole, olanzapine, pimozide, quetiapine, risperidone)
• apixaban
• "azole" antifungals (e.g., itraconazole, ketoconazole, voriconazole)
• barbiturates (e.g., butalbital, pentobarbital phenobarbital)
• benzodiazepines (e.g., chlordiazepoxide, clonazepam, diazepam, lorazepam)
• birth control pills (estrogens, progestins)
• bosentan
• buprenorphine
• buspirone
• calcitriol
• calcium channel blockers (e.g., amlodipine, diltiazem, nifedipine, verapamil)
• cannabis
• celecoxib
• chloroquine
• cobicistat
• colchicine
• conivaptan
• oral corticosteroids (e.g., dexamethasone, hydrocortisone, prednisone)
• cyclosporine
• dantrolene
• dapsone
• deferasirox
• diclofenac
• disopyramide
• dofetilide
• domperidone
• dronedarone
• eletriptan
• enzalutamide
• eplerenone
• estrogens (e.g., conjugated estrogen, estradiol, ethinyl estradiol)
• everolimus
• fentanyl
• fludrocortisone
• "gliptin" diabetes medications (e.g., linagliptin, saxagliptin, sitagliptin)
• grapefruit juice
• guanfacine
• HIV non-nucleoside reverse transcriptase inhibitors (NNRTIs; e.g., delavirdine, efavirenz, etravirine, nevirapine)
• HIV protease inhibitors (e.g., atazanavir, indinavir, ritonavir, saquinavir)
• hydrocodone
• hydroxyzine
• ivabradine
• losartan
• macrolide antibiotics (e.g., clarithromycin, erythromycin)
• maraviroc
• mefloquine
• methadone
• mifepristone
• mirtazapine
• modafinil
• naloxegol
• nefazodone
• nitrates (e.g., isosorbide dinitrate, isosorbide mononitrate)
• oxycodone
• pimecrolimus
• praziquantel
• primaquine
• progestins (e.g., dienogest, levonorgestrel, medroxyprogesterone, norethindrone)
• propafenone
• protein kinase inhibitors (e.g., bosutinib, crizotinib, dasatinib, erlotinib, imatinib, lapatinib, nilotinib, pazopanib)
• quinidine
• quinine
• rifabutin
• rifampin
• rilpivirine
• St. John's wort
• salmeterol
• seizure medications (e.g., carbamazepine, gabapentin, levetiracetam, phenytoin, topiramate)
• selective serotonin reuptake inhibitors (SSRIs; e.g., citalopram, fluoxetine, paroxetine, sertraline)
• serotonin/norepinephrine reuptake inhibitors (SNRIs; desvenlafaxine, duloxetine, venlafaxine)
• sildenafil
• siltuximab
• simeprevir
• sirolimus
• "statin" anti-cholesterol medications (e.g., atorvastatin, lovastatin, simvastatin)
• "sulfa" antibiotics (e.g., sulfamethoxazole, sulfadiazine)
• sulfonamide diabetes medications (e.g, gliclazide, glyburide)
• tacrolimus
• tamoxifen
• ticagrelor
• ticlopidine
• tocilizumab
• tolterodine
• tolvaptan
• trazodone
• tricyclic antidepressants (e.g., amitriptyline, clomipramine, desipramine, trimipramine)
• trimethoprim
• ulipristal
• warfarin
• zafirlukast
• zolpidem
• zopiclone

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.