Aprepitant to prevent sickness (Emend)

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Aprepitant is an anti-sickness medicine. It is taken alongside other medicines to help stop sickness after chemotherapy.

Take one 125 mg capsule an hour before chemotherapy, and then one 80 mg capsule each morning for the next two days.

The most common side-effects are hiccups, indigestion, constipation and headache.

Type of medicineNeurokinin-receptor antagonist anti-sickness medicine
Used forPrevention of sickness associated with chemotherapy in adults
Also calledEmend®
Available asCapsules

Aprepitant is known as a neurokinin-receptor antagonist. It is prescribed alongside other medicines to help stop you from feeling sick after chemotherapy. It works by blocking the effect of a naturally produced chemical, called 'substance P'.

Chemotherapy (or 'chemo' as it is often called) can cause the release of an increased amount of substance P. There are small areas in your brain called neurokinin1 receptors. Substance P acts on these receptors and causes you to feel sick. Aprepitant works by blocking substance P from acting on the neurokinin1 receptors, and this stops you from feeling (or being) sick.

Some medicines are not suitable for people with certain conditions, and sometimes a medicine may only be used if extra care is taken. For these reasons, before you start taking aprepitant it is important that your doctor knows:

  • If you are pregnant or breast-feeding.
  • If you have any problems with the way your liver works.
  • If you have ever had an allergic reaction to a medicine.
  • If you are taking any other medicines, including any medicines you are taking which are available to buy without a prescription, such as herbal and complementary medicines. Aprepitant interferes with a number of other medicines, including the 'pill' and 'mini pill'.
  • Before you start treatment, read the manufacturer's printed information leaflet from inside your pack. The manufacturer’s leaflet will give you more information about aprepitant and a full list of side-effects which you may experience from taking it.
  • Take aprepitant capsules exactly as your doctor tells you to. You will be asked to take one 125 mg capsule one hour before your chemo treatment starts, and then one 80 mg capsule each morning for the next two days.
  • Swallow the capsules whole - it may help to take your doses with a drink of water. It is not important whether you take the capsules before or after food.
  • If you forget to take a dose, contact your doctor for advice about what to do. Do not take two doses together to make up for a missed one.
  • Even if you do not feel like eating or drinking, try to sip water regularly to prevent you from becoming dehydrated.
  • Rather than trying to eat three main meals a day, try eating small, simple but nourishing snacks, every few hours.
  • If you are using hormonal contraception (this includes the 'pill' and 'mini pill'), additional contraceptive precautions such as a condom will be required while you are on aprepitant, and for two months afterwards. If you need further advice about this, speak with your doctor or pharmacist.
  • If you buy any medicines, check with a pharmacist that they are suitable to take with your other medicines. This is because many other medicines can interfere with aprepitant and therefore may not be recommended for you.

Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the most common ones associated with aprepitant. You will find a full list in the manufacturer's information leaflet supplied with your medicine. The unwanted effects often improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following continue or become troublesome.

Common aprepitant side-effects - these affect less than 1 in 10 people who take this medicine
What can I do if I experience this?
HeadacheAsk your doctor to prescribe/recommend a suitable painkiller
Feeling tiredDo not drive or use tools or machines
ConstipationTry to eat a well-balanced diet, and drink several glasses of water each day
Loss of appetite, hiccups, indigestionIf troublesome, speak with your doctor
Changes to some blood testsYour doctor will check for this

If you experience any other symptoms which you think may be due to this medicine, speak with your doctor or pharmacist.

  • Keep all medicines out of the reach and sight of children.
  • Store in a cool, dry place, away from direct heat and light.

Never take more than the prescribed dose. If you suspect that you or someone else might have taken an overdose of this medicine, go to the accident and emergency department of your local hospital. Take the container with you, even if it is empty.

This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.

If you are having an operation or any dental treatment, tell the person carrying out the treatment which medicines you are taking.

Do not keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.

If you have any questions about this medicine ask your pharmacist.

Further reading & references

  • Manufacturer's PIL, Emend® 80 mg, 125 mg hard Capsules; Merck Sharp & Dohme Limited, The electronic Medicines Compendium. Dated July 2013.
  • British National Formulary; 66th Edition (September 2013) British Medical Association and Royal Pharmaceutical Society of Great Britain, London

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.

Original Author:
Helen Allen
Current Version:
Peer Reviewer:
Dr Adrian Bonsall
Document ID:
28715 (v1)
Last Checked:
Next Review:
The Information Standard - certified member

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