Goserelin

Definition

Goserelin acetate is a synthetic (man-made) hormone that acts similarly to the naturally occurring gonadotropin-releasing hormone (GnRH). It is available in the United States under the tradename Zoladex.

Purpose

Goserelin acetate is used primarily to counter the symptoms of late-stage prostate cancer in men or is offered as an alternative to treat prostate cancer when surgery to remove the testes or estrogen therapy is not an option or is unacceptable for the patient. Goserelin is also given as combination therapy with the drug flutamide to manage prostate cancer that is locally confined and not widespread. It is often used to ease the pain and discomfort of women suffering from endometrosis and to relieve symptoms in women with advanced breast cancer.

Description

Goserelin acetate is a man-made protein that mimics many of the actions of gonadotropin-releasing hormone (GnRH). In men, this results in decreased blood levels of the male hormone testosterone. In women, it decreases blood levels of the female hormone estrogen.

Recommended dosage

Goserelin acetate is given in the form of an implant containing 3.6 mg of the medication. This implant is placed just under the skin of the upper abdominal wall. The drug lasts for 28 days, after which a new implant has to be placed. Goserelin is also available in a dose of 10.8 mg, in which case the drugs lasts for three months.

Precautions

If a woman becomes pregnant while taking this drug, goserelin acetate may cause birth defects or the loss of the pregnancy. It is not known if goserelin is passed into breast milk; therefore, it is not recommended to breast feed while on this drug.

Goserelin acetate will also interfere with the chemical actions of birth control pills. For this reason, sexually active women who do not wish to become pregnant should use some form of birth control other than birth control pills during treatment with goserelin acetate and for at least 12 weeks after the completion of treatment.

Goserelin acetate will cause sterility in men, at least for the duration of the treatment.

Side effects

In patients of both sexes, common side effects of goserelin acetate include:

• sweating accompanied by feelings of warmth (hot flashes)

• a decrease in sex drive

• depression or other mood changes

• headache

• tumor flare, which is exhibited as bone pain (this is due to a temporary initial increase in testosterone/estrogen before its production is finally decreased)

Other common side effects in men include:

• impotence (erectile dysfunction)

• sterility

• breast enlargement

Other common side effects in women include:

• light, irregular, vaginal bleeding

• no menstrual period

• vaginal dryness and/or itching

• emotional instability

• depression

• change in breast size

• an increase in facial or body hair

• deepening of the voice

Less common side effects, in patients of either sex, include:

• nausea and vomiting

• insomnia

• weight gain

• swollen feet or lower legs

• acne or other skin rashes

• abdominal pain

• increased appetite

A doctor should be consulted immediately if the patient experiences any of the above symptoms.

Interactions

There are no known interactions of goserelin acetate with any food or beverage.

Patients taking goserelin acetate should consult their physician before taking any other prescription, over-the-counter, or herbal medication. Patients taking any other hormone or steroid-based medications should not take goserelin acetate without first consulting their physician.

KEY TERMS

Endometrial tissue

The tissue lining the uterus that is sloughed off during a woman's menstrual period.

Gonadotropin releasing hormone (GnRH)

A hormone produced in the brain that controls the release of other hormones that are responsible for reproductive function.

Prostate gland

A small gland in the male genitals that contributes to the production of seminal fluid.