How Goserelin Acetate (Zoladex) Works

Goserelin acetate is an anti-cancer drug, classified as an analog of naturally occurring luteinizing hormone-releasing hormone (LHRH), and it is used for the treatment of prostate cancer, breast cancer, endometriosis, and abnormal bleeding of the uterus. “The acetate salt of a synthetic decapeptide analog of luteinizing hormone-releasing hormone (LHRH). Continuous, prolonged administration of goserelin in males results in inhibition of pituitary gonadotropin secretion, leading to a significant decline in testosterone production; in females, prolonged administration results in a decrease in estradiol production,” note the National Cancer Institute (NCI) Drug Dictionary.

Both breast and prostate cancer are the second most common types of cancer among women and men respectively, and its growth is often promoted by sex hormones. Therefore, the mechanism of action of goserelin acetate is based on interfering with these hormones to decrease their amount in the body and stop cancer growth. Goserelin acetate is available as an implant that is inserted by a doctor or nurse with a syringe subcutaneously in the area of the stomach. Depending on the patient’s needs and disease, the implant can have 3.6 mg of goserelin inserted every four weeks or 10.8 mg of goserelin to be implanted every 12 weeks. The length of the treatment also depends on the condition being treated and patient’s response to the medication.

Goserelin Acetate (Zoladex) for Breast Cancer

Goserelin acetate was first approved by the US Food and Drug Administration (FDA) on January 1996 for the treatment of localized prostate cancer in combination with flutamide and radiation therapy or as palliative treatment in advanced prostate cancer. It is commercialized under the brand name zoladex by AstraZeneca, and it is now also approved to be used as palliative treatment in premenopausal and perimenopausal women who suffer from advanced breast cancer. The approval of the drug was based on controlled studies that revealed the capacities of goserelin acetate similar to hormone suppression drugs.

The dosage recommended for patients with breast cancer is the three-month formulation of goserelin acetate in the form of a cylindrical implant with a 1.5 mm diameter that contains 10.8 mg of the drug. The treatment is provided through a subcutaneous injection, which slowly biodegrade and dissolve, delivering therapeutic levels of the drug continuously over a period of 12 weeks. There are, however, potential side effects associated with the treatment, which include headache, hot flashes, sweating, sudden reddening of the face, neck, or upper chest, lack of energy, loss of appetite, breast pain or change in breast size, decreased sexual desire or ability, painful sexual intercourse, vaginal discharge, dryness, or itching, swelling of the hands, feet, ankles, or lower legs, depression, nervousness, incapacity to control emotions and frequent mood changes, difficulty falling asleep or staying asleep, as well as pain, itching, swelling, or redness at the place where the implant was inserted.

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