How does it work?

Cetrotide injections contain the active ingredient cetrorelix, which is a synthetic form of a natural hormone called gonadotrophin releasing hormone (GnRH). It is known as a luteinising hormone releasing hormone antagonist. Cetrorelix is used together with another hormone called follicle stimulating hormone (FSH) in the treatment of infertility in women having assisted reproduction treatment, such as IVF.

Luteinising hormone releasing hormone (LHRH) is produced naturally in the body and acts on the pituitary gland in the brain. LHRH stimulates the release of two other hormones, luteinising hormone (LH) and follicle stimulating hormone (FSH).

Normally, in the ovaries in women, FSH increases the number of growing follicles and stimulates their development. Within the follicles are the developing eggs. FSH also increases the production of oestrogen, and under the influence of this hormone, the largest follicle continues to develop. As the amount of oestrogen in the blood increases, this triggers a surge of LH, which results in the release of an egg from the ovary (ovulation).

Assisted reproduction techniques such as IVF usually involve daily injections of FSH to artificially stimulate the production of follicles and eggs in the ovaries. This medicine is then given to block the action of natural LHRH in the pituitary gland. This prevents a premature surge of LH and allows the follicles to develop fully. When enough large follicles have developed, ovulation is then induced artificially with an injection of another hormone called human chorionic gonadotrophin (HCG), and the eggs are then harvested.

Treatment with Cetrotide is only given under the supervision of a specialist trained in the treatment of fertility problems. The injection is administered under the skin (subcutaneously), preferably in the lower abdomen.

What is it used for?

• Preventing premature ovulation in women having controlled ovarian hyperstimulation for assisted reproduction treatments, such as IVF.

Warning!

• Ovarian hyperstimulation syndrome (OHSS) can occur during or after treatment with FSH or menopausal gonadotrophin (which is a combination of FSH and LH). See the leaflet provided with your FSH or gonadotrophin injections for more information about this.
• If your fertility treatment does result in pregnancy, there are a few risks that you should be aware of. You should discuss these with your doctor before starting treatment. Pregnancy following assisted reproduction treatment is more likely to result in a multiple pregnancy (twins or more) than if you had conceived naturally. This carries an increased risk of problems for the mother during the pregnancy, and at or around the time of birth. There is a greater risk of miscarriage or abortion in women having fertility treatment than in the general population. There may also be a slightly higher risk of your baby being born with physical defects. There is a slightly higher risk of an ectopic pregnancy (where a fertilised egg implants outside the uterus) after IVF treatment than in the general population.

Use with caution in

• Women with signs and symptoms of active allergies or a history of allergies.

Not to be used in

• Allergy to other LHRH analogues, eg ganirelix.
• Moderate to severely decreased kidney function.
• Moderate to severely decreased liver function.
• Post-menopausal women.
• Pregnancy.
• Breastfeeding.

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.

• This medicine must not be used in women who are already pregnant or breastfeeding. 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. Just because a side effect is stated here does not mean that all people using this medicine will experience that or any side effect.

Common (affect between 1 in 10 and 1 in 100 people)

• Redness, swelling or itching at the injection site.

Uncommon (affect between 1 in 100 and 1 in 1000 people)

• Headache.
• Nausea.
• Allergic reactions, such as rash, hives, swelling of the face, breathing difficulties or anaphylaxis.

The side effects listed above may not include all of the side effects reported by the medicine'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 having treatment with this one, to make sure that the combination is safe.

Other medicines containing the same active ingredient

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