Aprepitant (Emend)

How does it work?

Emend capsules contain the active ingredient aprepitant, which is a type of medicine called a neurokinin receptor antagonist. It is used to prevent nausea and vomiting that can be caused by chemotherapy treatment for cancer.

Vomiting is controlled by an area of the brain called the vomiting centre. The vomiting centre is responsible for causing feelings of sickness (nausea) and for the vomiting reflex. It is activated when it receives nerve messages from another area of the brain called the chemoreceptor trigger zone (CTZ) and when it receives nerve messages from the gut.

A protein called substance P is involved in transmitting nerve messages to the vomiting centre. Substance P acts on neurokinin-1 receptors that are found in the vomiting centre in the brain.

Chemotherapy causes substance P to activate these neurokinin-1 receptors, resulting in feelings of sickness.

Aprepitant works by blocking the neurokinin-1 receptors in the brain. This stops substance P from acting on them and so prevents nausea and vomiting.

Aprepitant is used to prevent acute and delayed sickness that can be caused by chemotherapy, in particular by a medicine called cisplatin. It is given in combination with a steroid, eg dexamethasone, and a 5HT3 antagonist, eg ondansetron, as part of a three day regimen around each cycle of chemotherapy. These medicines all work in a different way to prevent sickness.

Emend capsules should be swallowed whole.

What is it used for?

  • Preventing nausea and vomiting caused by chemotherapy for cancer.

Warning!

  • This medicine could make hormonal contraceptives, eg the pill, mini-pill or patch less effective at preventing pregnancy. If you are using hormonal contraceptives, you should use an extra back-up method of contraception, eg condoms, to prevent pregnancy, both during treatment with this medicine and for two months after the last dose. Alternatively, your doctor may suggest that you use a different non-hormonal method of contraception instead. Ask your doctor or pharmacist for further advice.

Use with caution in

  • Moderate to severely decreased liver function.

Not to be used in

  • Rare hereditary problems of fructose intolerance, glucose-galactose malabsorption or sucrase-isomaltase insufficiency (Emend capsules contain sucrose).
  • This medicine is not recommended for children and adolescents under 18 years of age, as its safety and efficacy have not been studied in this age group.

This medicine should not be used if you are allergic to one or any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy.If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.

Pregnancy and Breastfeeding

Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.

  • The safety of this medicine during pregnancy has not been studied. It should not be used during pregnancy unless considered essential by your doctor. Seek medical advice from your doctor.
  • It is not known if this medicine pases into breast milk. Women who need this medicine should not breastfeed during treatment. Seek further medical advice from your doctor.

Side effects

Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Because a side effect is stated here, it does not mean that all people using this medicine will experience that or any side effect.

  • Hiccups
  • Feeling weak
  • Fatigue
  • Disturbances of the gut, such as constipation, diarrhoea, indigestion, abdominal pain, flatulence
  • Headache
  • Loss of appetite
  • Dizziness
  • Thirst
  • Disorientation
  • Anxiety
  • Abnormal dreams
  • Hot flushes
  • Sensation of ringing or other noise in the ears (tinnitus)
  • Slowed heart rate
  • Cough
  • Conjunctivitis
  • Dry mouth
  • Skin reactions such as rash or itching
  • Muscle cramps
  • Increased need to pass urine, pain passing urine

The side effects listed above may not include all of the side effects reported by the drug's manufacturer.For more information about any other possible risks associated with this medicine, please read the information provided with the medicine or consult your doctor or pharmacist.

How can this medicine affect other medicines?

It is important to tell your doctor or pharmacist what medicines you are already taking, including those bought without a prescription and herbal medicines, before you start treatment with this medicine. Similarly, check with your doctor or pharmacist before taking any new medicines while taking this one, to ensure that the combination is safe.

This medicine should not be taken in combination with the following medicines, as it could increase the amount of these medicines in the blood, potentially causing serious side effects:

  • astemizole
  • cisapride
  • pimozide
  • terfenadine.

Aprepitant may also increase the blood levels of various other medicines, including the following:

  • benzodiazepines, eg alprazolam, midazolam, triazolam
  • dexamethasone
  • dihydroergotamine
  • docetaxel
  • ergotamine
  • etoposide
  • irinotecan
  • methylprednisolone
  • paclitaxel
  • vinorelbine.

If you are having treatment with any of these medicines, you should let your doctor know if you get any new or increased side effects after you start taking this medicine. Your doctor may need to adjust your doses.

Aprepitant may decrease the blood levels of the following medicines, which could make them less effective:

  • phenytoin
  • tolbutamide.

Aprepitant may decrease the anti-blood-clotting effect of the anticoagulant medicine warfarin. If you regularly take warfarin your blood clotting time (INR) should be monitored closely, both while you are taking this medicine and for two weeks following each three day course.

Aprepitant may reduce the effectiveness of hormonal contraceptives, eg the pill, mini-pill or patch. If you are using hormonal contraceptives, you should use an extra back-up method of contraception, eg condoms, to prevent pregnancy, both during treatment with this medicine and for two months after the last dose. Alternatively, your doctor may suggest that you use a different non-hormonal method of contraception instead.

The following medicines are not recommended while you are having treatment with this medicine, as they could decrease the amount of aprepitant in your blood and make it less effective:

  • carbamazepine
  • phenobarbital
  • phenytoin
  • rifampicin
  • the herbal remedy St John's wort (Hypericum perforatum).

The following medicines should be used with caution while you are having treatment with this medicine, as they could increase the amount of aprepitant in your blood and so increase the risk of side effects:

  • clarithromycin
  • ketoconazole
  • ritonavir
  • telithromycin.

Other medicines containing the same active ingredient

There are currently no other medicines available in the UK that contain aprepitant as the active ingredient.