How does this medication work? What will it do for me?

Cetrorelix belongs to the class of medications called GnRH antagonists. Cetrorelix is used to prevent premature ovulation in women undergoing ovarian stimulation. It blocks the effects of gonadotropin-releasing hormone (GnRH). GnRH controls the secretion of another hormone, called luteinizing hormone (LH), a hormone that starts ovulation (release of an egg) during the menstrual cycle. Cetrorelix allows the release of an egg to be controlled so it is released at the best time for pregnancy to occur.

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 using this medication, speak to your doctor. Do not stop using 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.

What form(s) does this medication come in?

0.25 mg
Each single dose vial (multiple dose regimen) of sterile lyophilized powder contains 0.25 mg of cetrorelix as cetrorelix acetate and 54.80 mg of mannitol. Cartons of one packaged tray. Each packaged tray contains one glass vial containing 0.25 mg of cetrorelix acetate, one prefilled glass syringe with 1 mL of sterile water for injection, Ph.Eur., one 20 gauge needle (yellow), one 27 gauge needle (grey), and two alcohol swabs.

How should I use this medication?

The usual dose of cetrorelix is either 0.25 mg once daily injected under the skin or as a single 3 mg dose injected under the skin. Cetrorelix should be injected under the skin of the lower abdominal wall as directed by your doctor. If you are using cetrorelix daily, use a different injection site each day to reduce irritation.

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.

This medication is best injected under the skin of the lower abdomen a few inches below your navel. Each day, use the alternate side of your lower abdomen (e.g., left or right) to prevent soreness.

Your doctor or other health care professional will show you exactly how to mix and draw up the medication into the needles and how to inject it. Read the information leaflet carefully and ask your doctor any questions you may have.

Once the dose of medication has been prepared, it should be used immediately. Discard any unused material after use. Do not use your injectable solution if it appears cloudy, lumpy, or discoloured.

It is important to use this medication exactly as prescribed by your doctor. If you miss a dose, contact your doctor for instructions. Do not take a double dose to make up for a missed one.

Store this medication in a cool dry place between 2°C and 25°C. Do not freeze. Protect it from heat, moisture, and light and keep it out of the reach of children.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Do not use this medication if you:

  • are allergic to cetrorelix, extrinsic peptide hormones, mannitol, or any ingredients of the medication
  • are allergic to gonadotropin-releasing hormone (GnRH) or other GnRH-related hormones (e.g., leuprolide, goserelin)
  • are or may be pregnant
  • are breast-feeding
  • have moderate-to-severe liver function impairment
  • have moderate-to-severe kidney function impairment

What side effects are possible with this medication?

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 uses 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 using 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.

  • headache
  • nausea
  • redness, swelling, bruising, and itching at the place of injection

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.

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

  • signs of a severe allergic reactions such as hives; difficulty breathing; swelling of the tongue, face, mouth, or throat
  • symptoms of ovarian hyperstimulation syndrome (OHSS), e.g.:
    • abdominal or pelvic pain or discomfort
    • bloating
    • decreased amount of urine
    • diarrhea
    • difficulty breathing
    • nausea
    • rapid weight gain
    • vomiting

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.

Are there any other precautions or warnings for 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.

Allergic reactions: Severe allergic reactions and anaphylactic reactions have been reported with the use of cetrorelix. If you have active allergies or are prone to allergies, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Ovarian hyperstimulation syndrome (OHSS): Cetrorelix is used to prevent premature ovulation in women undergoing ovarian stimulation. Ovarian stimulation can cause a condition called ovarian hyperstimulation syndrome (OHSS). It may develop during or after ovarian stimulation. With OHSS, too many follicles grow and cause abdominal discomfort or pain, nausea, diarrhea, and sometimes difficulty breathing. If you experience any of these symptoms, contact your doctor immediately.

Pregnancy: The effect of cetrorelix on an unborn baby is not known. To avoid the possibility of harm to the baby, cetrorelix should not be used during pregnancy.

Breast-feeding: It is not known if cetrorelix passes into breast milk. If you are a breast-feeding mother and are taking this medication, it may affect your baby. Women who are taking this medication should not breast-feed.

Children: This medication is intended for use by women of child-bearing age. Its safety and effectiveness have not been established for children.

Seniors: This medication is intended for use by women of child-bearing age. Its safety and effectiveness have not been established for seniors.

What other drugs could interact with this medication?

Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications that 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. 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.