EMEND (Aprepitant)
NK1 Receptor Antagonist for Prevention of Chemotherapy-Induced Nausea and Vomiting
Quick Facts About EMEND
Key Takeaways About EMEND
- Used in combination therapy: EMEND is always taken with other antiemetics (a 5-HT3 antagonist like ondansetron and a corticosteroid like dexamethasone) for optimal protection against chemotherapy-induced nausea and vomiting
- 3-day regimen: Day 1: 125 mg (1 hour before chemo); Day 2 and 3: 80 mg each morning. Simple dosing schedule that is easy to follow
- Affects hormonal contraceptives: Birth control pills, patches, and implants may be less effective during treatment and for up to 2 months after. Use alternative non-hormonal contraception
- Important drug interactions: Must not be taken with pimozide, terfenadine, astemizole, or cisapride. Many other medications require dose adjustments
- Generally well tolerated: Most common side effects are mild, including constipation, headache, fatigue, and hiccups
What Is EMEND and What Is It Used For?
EMEND (aprepitant) is an antiemetic medication that prevents nausea and vomiting caused by chemotherapy. It belongs to the neurokinin 1 (NK1) receptor antagonist class and works by blocking substance P signals in the brain's vomiting center. It is used in adults and adolescents from 12 years of age.
EMEND contains the active substance aprepitant, which belongs to a group of medicines called neurokinin 1 (NK1) receptor antagonists. The brain contains a specific area that controls nausea and vomiting. EMEND works by blocking signals to this area, thereby reducing the sensation of nausea and the urge to vomit. This makes it an essential component of modern antiemetic therapy for cancer patients undergoing chemotherapy.
Chemotherapy-induced nausea and vomiting (CINV) is one of the most feared side effects of cancer treatment, affecting up to 80% of patients receiving certain chemotherapy regimens. CINV can significantly impact quality of life, nutritional status, and in severe cases, may lead patients to delay or refuse further treatment cycles. The development of NK1 receptor antagonists like aprepitant has been a major advancement in managing this challenging side effect.
EMEND capsules are used in combination with other antiemetic medications to prevent nausea and vomiting caused by cytostatic drugs (chemotherapy) that are highly or moderately emetogenic (likely to cause nausea and vomiting), such as cisplatin, cyclophosphamide, doxorubicin, or epirubicin. It is important to understand that EMEND is not used alone but rather as part of a multi-drug antiemetic regimen, typically including a 5-HT3 receptor antagonist (such as ondansetron or granisetron) and a corticosteroid (such as dexamethasone).
How Does Aprepitant Work?
Aprepitant is a selective, high-affinity antagonist of human substance P neurokinin 1 (NK1) receptors. Substance P is a neuropeptide that plays a crucial role in the emetic (vomiting) reflex. When chemotherapy drugs damage cells in the gastrointestinal tract, substance P is released and binds to NK1 receptors in the brain's nucleus tractus solitarius and area postrema (the vomiting center), triggering both acute and delayed nausea and vomiting.
By blocking these NK1 receptors, aprepitant prevents substance P from activating the vomiting reflex. This mechanism is particularly important for controlling delayed CINV (occurring 24 hours or more after chemotherapy), which is largely mediated by substance P and is often poorly controlled by other antiemetics alone. The combination of an NK1 antagonist with a 5-HT3 antagonist and dexamethasone addresses multiple pathways involved in CINV, providing comprehensive protection.
Chemotherapy-induced nausea and vomiting occurs in two phases: acute phase (within 24 hours of chemotherapy, primarily mediated by serotonin) and delayed phase (24-120 hours after chemotherapy, primarily mediated by substance P). EMEND is particularly effective against the delayed phase, which historically has been the most difficult to control.
What Should You Know Before Taking EMEND?
Before taking EMEND, tell your doctor about all medications you use, any liver disease, allergies, and if you are pregnant, breastfeeding, or planning to become pregnant. EMEND must not be taken with pimozide, terfenadine, astemizole, or cisapride due to potentially dangerous interactions.
Contraindications
You must not take EMEND in the following situations:
- If you are allergic to aprepitant or any of the other ingredients in the medicine
- Together with medicines containing pimozide (used for psychiatric conditions) - risk of serious heart rhythm disturbances
- Together with terfenadine or astemizole (used for hay fever and other allergic conditions) - risk of cardiac arrhythmias
- Together with cisapride (used for digestive problems) - risk of serious cardiac effects
These contraindicated medications are metabolized by the CYP3A4 enzyme, and aprepitant's inhibition of this enzyme can lead to dangerously elevated blood levels of these drugs, potentially causing life-threatening cardiac arrhythmias including QT prolongation and torsade de pointes. If you are taking any of these medications, inform your doctor so that your treatment plan can be adjusted before starting EMEND.
Warnings and Precautions
Talk to your doctor, pharmacist, or nurse before taking EMEND if you have any liver disease. The liver plays an important role in breaking down this medicine in the body, and your doctor may need to monitor your liver function during treatment. Patients with severe hepatic impairment (Child-Pugh score greater than 9) should be monitored closely, as there is limited clinical data in this population.
EMEND 80 mg and 125 mg capsules should not be given to children under 12 years of age, as these capsule strengths have not been studied in younger children. For pediatric patients under 12, alternative formulations or dosing strategies should be discussed with a healthcare provider.
Pregnancy and Breastfeeding
EMEND should not be used during pregnancy unless it is absolutely necessary. If you are pregnant or think you may be pregnant, or are planning to become pregnant, consult your doctor before using this medicine. Animal reproductive studies have shown some effects, and the potential risk to human pregnancy is not fully established.
Regarding contraception, this is a particularly important consideration: hormonal contraceptives including birth control pills, patches, implants, and certain hormone-releasing intrauterine devices may become less effective when used together with EMEND. Alternative or supplementary non-hormonal contraception should be used during treatment with EMEND and for up to 2 months after the last dose of EMEND. This extended period is necessary because aprepitant's effects on the enzyme that metabolizes hormonal contraceptives can persist beyond the treatment period.
It is not known whether EMEND passes into breast milk, and therefore breastfeeding is not recommended during treatment with this medicine. Discuss the risks and benefits with your doctor if breastfeeding is important to you.
Driving and Operating Machinery
Some patients may experience dizziness and drowsiness after taking EMEND. If you feel dizzy or sleepy after using this medicine, avoid driving, cycling, or using machines or tools until these effects have resolved. This is particularly relevant given that many chemotherapy patients already experience fatigue from their cancer treatment.
EMEND capsules contain sucrose. If your doctor has told you that you have an intolerance to certain sugars, contact your doctor before taking this medicine. The capsules also contain less than 1 mmol (23 mg) of sodium per capsule, meaning they are essentially sodium-free.
How Does EMEND Interact with Other Drugs?
EMEND can affect many medications both during and after treatment. It must not be used with pimozide, terfenadine, astemizole, or cisapride. It can reduce the effectiveness of hormonal contraceptives and alter blood levels of warfarin, immunosuppressants, certain chemotherapy drugs, benzodiazepines, and many other medications.
Aprepitant is both a substrate and a moderate inhibitor of the cytochrome P450 3A4 (CYP3A4) enzyme and an inducer of CYP2C9. This means it can significantly affect the metabolism of many other medications, potentially increasing or decreasing their blood levels. Understanding these interactions is crucial for safe and effective treatment. Always inform your doctor and pharmacist about all medications you are taking, including over-the-counter medicines, herbal remedies, and dietary supplements.
Major Interactions (Contraindicated or Requiring Special Caution)
| Medication | Category | Effect | Action Required |
|---|---|---|---|
| Pimozide | Antipsychotic | Increased pimozide levels; risk of cardiac arrhythmia | Contraindicated - Do not combine |
| Terfenadine, Astemizole | Antihistamines | Increased levels; risk of QT prolongation | Contraindicated - Do not combine |
| Cisapride | Prokinetic | Increased cisapride levels; risk of cardiac effects | Contraindicated - Do not combine |
| Hormonal contraceptives | Contraception | Reduced contraceptive effectiveness | Use alternative non-hormonal method during and 2 months after |
| Warfarin, Acenocoumarol | Anticoagulants | Altered INR; reduced anticoagulant effect | Monitor INR closely; dose adjustment may be needed |
| Cyclosporine, Tacrolimus, Sirolimus, Everolimus | Immunosuppressants | Increased immunosuppressant levels | Monitor drug levels; dose adjustment may be needed |
| Ergotamine, Dihydroergotamine | Migraine medications | Increased ergot levels; risk of ergotism | Avoid combination |
Other Notable Interactions
| Medication | Category | Clinical Significance |
|---|---|---|
| Dexamethasone | Corticosteroid | Increased levels - oral dexamethasone dose should be reduced by ~50% when co-administered |
| Methylprednisolone | Corticosteroid | Increased levels - IV dose by ~25%, oral dose by ~50% |
| Midazolam, Triazolam | Benzodiazepines | Increased sedative levels; increased drowsiness risk |
| Irinotecan, Etoposide, Vinorelbine, Ifosfamide | Chemotherapy drugs | Potentially altered chemotherapy drug levels; monitor for toxicity |
| Alfentanil, Fentanyl | Opioid analgesics | Increased opioid levels; risk of enhanced sedation |
| Ketoconazole, Itraconazole, Voriconazole | Antifungals (CYP3A4 inhibitors) | Increased aprepitant levels; use with caution |
| Rifampicin | Antibiotic (CYP3A4 inducer) | Significantly decreased aprepitant levels; reduced efficacy |
| Phenytoin, Carbamazepine | Antiepileptics (CYP3A4 inducers) | Decreased aprepitant levels; reduced efficacy |
| St. John's Wort | Herbal (CYP3A4 inducer) | May significantly reduce aprepitant levels; avoid concurrent use |
The effects of EMEND on other medications can persist beyond the treatment period. When EMEND is given as a 3-day regimen, it acts as a moderate CYP3A4 inhibitor during the first days and then transiently induces CYP3A4 and CYP2C9 afterwards. This means dose adjustments of concomitant medications may be needed both during and after EMEND use. Always tell your doctor about all medications you take.
What Is the Correct Dosage of EMEND?
EMEND follows a 3-day regimen: 125 mg on Day 1 (1 hour before chemotherapy) and 80 mg on Days 2 and 3 (in the morning). Capsules should be swallowed whole with liquid and can be taken with or without food. Always take EMEND together with other prescribed antiemetic medications.
Always take EMEND exactly as your doctor, pharmacist, or nurse has instructed. EMEND should always be taken together with other medicines to prevent nausea and vomiting. After completing the 3-day EMEND regimen, your doctor will typically ask you to continue taking other antiemetic medicines, including a corticosteroid (such as dexamethasone) and a 5-HT3 antagonist (such as ondansetron), to maintain protection against delayed nausea and vomiting.
Adults and Adolescents (12 Years and Older)
Day 1 - Chemotherapy Day
125 mg (one capsule) taken 1 hour before the start of chemotherapy. Take with a full glass of water. Can be taken with or without food.
Day 2 - Day After Chemotherapy
80 mg (one capsule) taken in the morning. If no chemotherapy is administered, take EMEND in the morning at approximately the same time as Day 1. Can be taken with or without food.
Day 3 - Second Day After Chemotherapy
80 mg (one capsule) taken in the morning. If chemotherapy is administered, take EMEND 1 hour before the treatment session begins. Can be taken with or without food.
| Day | EMEND Dose | Timing | Additional Antiemetics |
|---|---|---|---|
| Day 1 | 125 mg (1 capsule) | 1 hour before chemotherapy | 5-HT3 antagonist + dexamethasone |
| Day 2 | 80 mg (1 capsule) | Morning | Dexamethasone (reduced dose) |
| Day 3 | 80 mg (1 capsule) | Morning | Dexamethasone (reduced dose) |
| Day 4 | No EMEND | - | Dexamethasone (as directed) |
Children Under 12 Years
EMEND 80 mg and 125 mg capsules should not be given to children under 12 years of age, as these capsule strengths have not been studied in this age group. For younger pediatric patients, healthcare providers may consider alternative formulations or other antiemetic strategies. Discuss all options with your child's oncologist.
Elderly Patients
No dose adjustment is required for elderly patients. Clinical studies have included patients over 65 years of age, and the safety and efficacy profile was consistent with that observed in younger adults. However, as with all medications, elderly patients should be monitored for potential adverse effects, particularly given the greater frequency of decreased hepatic, renal, or cardiac function in this population.
Missed Dose
If you have missed a dose of EMEND, contact your doctor for advice. Do not take a double dose to make up for a forgotten capsule. The timing of EMEND doses is coordinated with your chemotherapy schedule, so it is important to follow your doctor's specific instructions about what to do if a dose is missed.
Overdose
Do not take more capsules than your doctor recommends. If you or someone else has taken too many capsules, contact your doctor or local poison control center immediately. In clinical studies, single doses up to 600 mg of aprepitant were generally well tolerated, but symptoms such as drowsiness and headache were reported. There is no specific antidote for aprepitant overdose, and treatment is supportive.
Swallow the capsule whole with a full glass of liquid. Do not crush, chew, or open the capsule. EMEND can be taken with or without food. The capsules should only be removed from the blister packaging when you are ready to take them, as the product is moisture-sensitive.
What Are the Side Effects of EMEND?
Like all medicines, EMEND can cause side effects, though not everyone experiences them. The most common side effects include constipation, indigestion, headache, fatigue, decreased appetite, and hiccups. Serious allergic reactions (hives, difficulty breathing) are rare but require immediate medical attention.
Clinical trials and post-marketing surveillance have identified a range of side effects associated with aprepitant. It is important to remember that you are typically taking EMEND alongside chemotherapy and other antiemetic medications, so some symptoms may be attributable to these other treatments rather than EMEND itself. The following side effects have been reported:
Stop taking EMEND and contact a doctor immediately if you notice hives, rash, itching, difficulty breathing, or difficulty swallowing. These may be signs of a serious allergic reaction that requires emergency medical care. The frequency of these reactions is not known (cannot be estimated from available data).
Common Side Effects
- Constipation
- Indigestion (dyspepsia)
- Headache
- Fatigue (tiredness)
- Decreased appetite
- Hiccups
- Elevated liver enzymes in blood tests
Uncommon Side Effects
- Dizziness, drowsiness
- Acne, skin rash
- Anxiety
- Belching, nausea, vomiting, heartburn, stomach pain, dry mouth, flatulence
- Increased painful or burning urination
- Weakness, general malaise
- Hot flushes, facial redness or skin redness
- Rapid or irregular heartbeat
- Fever with increased risk of infection, decreased red blood cell count
Rare Side Effects
- Difficulty thinking, lack of energy, taste changes
- Skin sensitivity to sunlight, increased sweating, oily skin, skin ulcers, itchy rash
- Stevens-Johnson syndrome / toxic epidermal necrolysis (severe skin reactions)
- Euphoria (extreme feeling of happiness), disorientation
- Bacterial infection, fungal infection
- Severe constipation, stomach ulcer, intestinal inflammation, mouth ulcers, abdominal distension
- Frequent urination, increased urine volume, sugar or blood in urine
- Chest discomfort, swelling, altered gait
- Cough, postnasal drip, throat irritation, sneezing, sore throat
- Watery and itchy eyes, tinnitus (ringing in the ears)
- Muscle spasms, muscle weakness, increased thirst
- Slow heartbeat, cardiovascular disease
- Decreased white blood cells, low sodium levels, weight loss
Most common side effects of EMEND are mild to moderate in severity and are self-limiting. Elevated liver enzymes are usually transient and return to normal after treatment is discontinued. If you experience any persistent or bothersome side effects, discuss them with your healthcare provider. It is important to report any suspected adverse reactions to help continuously monitor the benefit-risk balance of the medicine.
Although extremely rare, Stevens-Johnson syndrome and toxic epidermal necrolysis are serious skin reactions that have been reported with EMEND use. Seek immediate medical help if you develop a widespread rash with blisters, peeling skin, or sores in the mouth, eyes, or genitals, especially if accompanied by fever and flu-like symptoms.
How Should You Store EMEND?
Store EMEND out of sight and reach of children. Keep capsules in original packaging until ready to use as the product is moisture-sensitive. Check the expiry date on the carton before use and do not use after this date. Dispose of unused medicines responsibly through a pharmacy.
Proper storage of EMEND is essential to ensure the medication remains effective throughout its shelf life. Follow these storage guidelines:
- Keep out of sight and reach of children at all times
- Do not use after the expiry date stated on the carton after "EXP." The expiry date refers to the last day of the indicated month
- Store in the original packaging to protect from moisture - the product is moisture-sensitive
- Do not push the capsule out of the blister until you are ready to take it
- No special temperature requirements for storage
Do not dispose of medicines in wastewater or household waste. Ask your pharmacist how to properly dispose of medicines that are no longer needed. These measures help protect the environment and ensure safe disposal of pharmaceutical products.
What Does EMEND Contain?
EMEND capsules contain aprepitant as the active ingredient (80 mg or 125 mg per capsule). Inactive ingredients include sucrose, microcrystalline cellulose, hydroxypropylcellulose, sodium lauryl sulfate, gelatin, titanium dioxide, and iron oxides for coloring.
Active Ingredient
The active substance is aprepitant. Each 125 mg hard capsule contains 125 mg aprepitant. Each 80 mg hard capsule contains 80 mg aprepitant.
Inactive Ingredients (Excipients)
The other ingredients include: sucrose, microcrystalline cellulose (E460), hydroxypropylcellulose (E463), sodium lauryl sulfate, gelatin, titanium dioxide (E171), shellac, potassium hydroxide, and black iron oxide (E172). The 125 mg capsule also contains red iron oxide (E172) and yellow iron oxide (E172).
Capsule Appearance
- 125 mg capsule: Opaque with white body and pink cap. "462" and "125 mg" are printed in black ink on the body of the capsule
- 80 mg capsule: Opaque with white body and white cap. "461" and "80 mg" are printed in black ink on the body of the capsule
Available Pack Sizes
EMEND 125 mg and 80 mg hard capsules are available in the following pack sizes:
- Aluminium blister containing one 80 mg capsule
- 2-day treatment pack containing two 80 mg capsules
- 5 aluminium blisters each containing one 80 mg capsule
- Aluminium blister containing one 125 mg capsule
- 5 aluminium blisters each containing one 125 mg capsule
- 3-day treatment pack containing one 125 mg capsule and two 80 mg capsules (most common pack for standard regimen)
Not all pack sizes may be marketed in all countries. The 3-day treatment pack is specifically designed to provide all the capsules needed for one complete treatment cycle.
Manufacturer
EMEND is manufactured by Merck Sharp & Dohme B.V., Waarderweg 39, 2031 BN Haarlem, Netherlands. Generic versions containing aprepitant are also available from other manufacturers, such as Aprepitant STADA.
Frequently Asked Questions About EMEND
Medical References and Sources
This article is based on current medical research and international guidelines. All claims are supported by scientific evidence from peer-reviewed sources.
- European Medicines Agency (EMA). "EMEND - Summary of Product Characteristics (SmPC)." Official EU product information for EMEND (aprepitant). Last updated 2025.
- U.S. Food and Drug Administration (FDA). "EMEND (aprepitant) Prescribing Information." Merck Sharp & Dohme LLC. FDA-approved prescribing information for healthcare professionals.
- MASCC/ESMO (2023). "Antiemetic Guidelines." Multinational Association of Supportive Care in Cancer / European Society for Medical Oncology. International consensus guidelines for prevention of chemotherapy-induced nausea and vomiting.
- Hesketh PJ, et al. (2024). "Antiemetics: ASCO Guideline Update." Journal of Clinical Oncology. American Society of Clinical Oncology updated guidelines on antiemetic use in oncology.
- World Health Organization (WHO) (2023). "Model List of Essential Medicines." WHO's list of essential medicines for global healthcare.
- Warr DG, et al. (2005). "Efficacy and tolerability of aprepitant for the prevention of chemotherapy-induced nausea and vomiting in patients with breast cancer after moderately emetogenic chemotherapy." Journal of Clinical Oncology. 23(12):2822-2830. Landmark clinical trial demonstrating aprepitant efficacy in moderately emetogenic chemotherapy.
- Hesketh PJ, et al. (2003). "The oral neurokinin-1 antagonist aprepitant for the prevention of chemotherapy-induced nausea and vomiting." New England Journal of Medicine. 348(13):1293-1299. Pivotal NEJM study establishing the role of NK1 antagonists in CINV prevention. Evidence level: 1A.
- NCCN Clinical Practice Guidelines in Oncology (2025). "Antiemesis." National Comprehensive Cancer Network. US clinical practice guidelines for antiemetic therapy in cancer patients.
Evidence grading: This article uses the GRADE framework (Grading of Recommendations Assessment, Development and Evaluation) for evidence-based medicine. The information is based on randomized controlled trials, systematic reviews, and official product information from regulatory agencies (EMA, FDA).
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