Gonapeptyl depot

How does it work?

Gonapeptyl depot injection contains the active ingredient triptorelin acetate, which is a type of medicine known as a gonadorelin (LHRH) analogue. It acts on the pituitary gland in the brain.

The pituitary gland produces and stores various hormones, including the sex hormones, luteinising hormone (LH) and follicle-stimulating hormone (FSH). In men, LH released from the pituitary gland causes the testicles to produce testosterone. FSH and testosterone cause the production of sperm by the testicles. In women, FSH and LH cause the production of oestrogen by the ovaries and help control the menstrual cycle.

The amount of LH and FSH released from the pituitary gland is controlled by another hormone, called gonaderelin (LHRH). Gonadorelin acts on LHRH receptors in the pituitary gland, causing the release of LH and FSH and hence the subsequent production of testosterone in men and oestrogen in women.

Triptorelin is a synthetic form of gonaderelin. It acts on the LHRH receptors in the pituitary gland in the same way as natural gonadorelin.

Initially, triptorelin causes an increase in the amount of FSH and LH released from the pituitary gland, with resulting increase in testosterone production in men, and oestrogen production in women. However, chronic administration of triptorelin desensitises the pituitary gland. This means that it produces less and less FSH and LH, which in turn stops the production of oestrogens in women and testosterone in men. This reduction in the levels of sex hormones caused by triptorelin is used to treat disorders that are linked to levels of oestrogen or testosterone.

In men, the growth of some prostate cancers is stimulated by testosterone. Reducing the body's levels of testosterone therefore deprives the tumour of testosterone and causes it to shrink. Gonapeptyl depot is given as a monthly injection to treat advanced prostate cancer in men.

The triptorelin may at first increase testosterone levels and so it may cause an initial temporary tumour 'flare', with symptoms such as urinary obstruction and bone pain, before the cancer begins to shrink. Some men may be particularly prone to these symptoms. If this applies to you your doctor will also treat you with another type of anti-cancer medicine, known as an anti-androgen (eg cyproterone acetate or flutamide) to prevent this. The anti-androgen will be started three days before the triptorelin and continued for the first two to three weeks of treatment.

In women, endometriosis and uterine fibroids are treated with triptorelin. Endometriosis is a condition where tissue resembling the womb or uterus lining (endometrium) is found in other sites in the body. The growth of this tissue is stimulated by oestrogen, so decreasing oestrogen levels with triptorelin will stop the growth of this tissue, thereby relieving symptoms. Gonapeptyl depot is given as a monthly injection for up to six months to treat endometriosis, starting in the first five days of the menstrual cycle.

The growth of fibroids in the uterus is also stimulated by oestrogen, so triptorelin is used to decrease oestrogen levels and so decrease the size of fibroids prior to surgery. Gonapeptyl depot injection is given every month, again starting in the first five days of the menstrual cycle, for up to six months.

Triptorelin can also be used to treat unexpectedly early puberty - occuring in girls aged under 9 years and boys aged under 10 years. In this case, triptorelin is given to block the production of sex hormones that is causing the premature puberty. Gonapeptyl depot is given on days 0, 14, and 28 to start treatment and then as a monthly injection. Treatment is stopped when bone development has reached that expected in girls older than 12 years and boys older than 13 years.

What is it used for?

Advanced prostate cancer

Endometriosis

Fibroids of the uterus

Premature puberty in girls aged under 9 years and boys aged under 10 years

Warning!

The site that the injection is given into should be varied periodically.

This medicine should cause womens' menstrual periods to stop. If you are still experiencing menstrual bleeds despite treatment, you should consult your doctor.

Girls receiving this medicine for early puberty may experience vaginal bleeding aftert first starting treatment. This is normal.

Triptorelin inhibits ovulation, but it is not a reliable contraceptive. Women should use non-hormonal methods of contraception to prevent pregnancy during treatment, as this medicine may be harmful to a developing baby. If you miss a dose of this medicine, breakthrough bleeding or ovulation may occur. Since this increases the risk of getting pregnant, you should continue using contraception if you miss a dose. Consult your doctor if you think you could be pregnant.

Use with caution in

Men considered by their doctor to be at risk of an initial worsening of their tumour symptoms (tumour flare) when starting treatment

Men with urinary obstruction

Men whose cancer has spread to the spine or is pressing on the spinal cord

Women at risk of osteoporosis, eg due to a strong family history, or chronic use of other drugs which reduce bone density, including corticosteroids, alcohol and tobacco

Not to be used in

Men with cancer that is not stimulated by testosterone

Men who have had surgery to remove the testicles

Women with osteoporosis

Pregnancy

Breastfeeding

Vaginal bleeding of unknown cause

Children with progressive brain tumours

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 should not be used during pregnancy. A non-hormonal method of contraception, eg condoms or diaphragm, should be used by women who could get pregnant. This should be continued for one month after the last injection. Seek medical advice from your doctor.

It is not known if this medicine passes into breast milk. However, because it could be harmful to a nursing infant if it did pass into milk, this medicine should not be used to treat women who are breastfeeding. Seek 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.

General side effects:

Pain, redness or hardening of skin at injection site

Hot flushes

Dizziness

Sweating

Headache

Decreased sex drive

Mood changes

Disturbances of the gut such as diarrhoea, constipation, nausea, vomiting or abdominal pain

Weight gain

Visual disturbances

Difficulty sleeping (insomnia)

Excessive fluid retention in the body tissues, resulting in swelling (oedema)

Pain in the muscles and joints

Increase in blood pressure

Side effects in men:

Impotence

Abnormal enlargement of breasts (gynaecomastia)

Side effects in women:

Vaginal dryness

Breast pain

Hair loss (alopecia)

Decreased bone density

Side effects in children:

Nausea and vomiting

Vaginal bleeding or discharge

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.

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