Home » Drug Information » FDA Approved Drugs » 1996
Medical Areas: Endocrinology | Nephrology | Oncology | Family Medicine | Urology
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Zoladex (10.8 mg goserelin acetate implant)
The following drug information is obtained from various newswires, published
medical journal articles, and medical conference presentations.
Approval Status: Approved January 1996
Treatment Area: prostate cancer
The original 3.6 mg formulation of Zoladex has been available
since 1989 as a monthly implant. The new formation, 10.8 mg
goserelin acetate implant given every three months, offers greater
convenience to subjects choosing treatment with a
luteinizing-hormone-releasing hormone (LHRH) analogue. The 3.6 mg
formulation of Zoladex was shown to be as effective as orchiectomy
(surgical castration) in controlling the spread of prostate cancer,
thus offering men a choice between medical treatment and
The growth of prostate cancer can be stimulated by the male
hormone testosterone. Treatment with Zoladex as a subcutaneous
injection results in a decline in testosterone, which then reduces
stimulation of hormone-responsive prostate tumors.
The 3-month formulation of Zoladex is a cylindrical implant with
a 1.5 mm diameter that contains 10.8 mg of goserelin. Given by
subcutaneous injection, the biodegradable implant slowly dissolves,
delivering therapeutic levels of the drug continuously over a
period of 12 weeks.
In controlled studies of subjects with advanced prostate cancer,
the Zoladex 10.8 mg formulation produced pharmacodynamically
similar effect in terms of testosterone suppression to that
achieved with the 3.6 mg formulation.
The most frequently reported adverse effects in clinical trials
with the 10.8 mg formulation were hot flashes and pain.
Mechanism of Action
Zoladex is an analogue of naturally occurring LHRH. Continuous
administration of Zoladex results in a significant decline in
testosterone production by the testicles. This reduces testosterone
stimulation of prostate cancer growth.
The once-a-month Zoladex 3.6 mg formulation was recently cleared
by the FDA for the treatment of advanced breast cancer in
premenopausal and perimenopausal women. Since 1993, Zoladex has
also been used as a treatment for endometriosis, a noncancerous
gynecological condition affecting an estimated five million women
in the United States.
Prostate cancer is the most common cancer (other than skin
cancers) among men in the United States. According to the American
Cancer Society, some 244,000 men will be diagnosed with the disease
in 1995, and 40,400 men will die of it.