Goserelin

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Overview
Goserelin Acetate is an injectable gonadotropin releasing hormone super-agonist (GnRH agonist). It stops the production of sex hormones (testosterone and oestrogen).

Goserelin Acetate is marketed by AstraZeneca with the brand name Zoladex. It was first launched in 1987 and is currently the second-largest selling GnRH analogue in the world. It is currently available in more than one hundred markets.

Zoladex 3.6 mg subcutaneous monthly biodegradable implant was first approved by the FDA on November 3, 1989 for treatment of prostate cancer, a 10.8 mg subcutaneous 3-month biodegradable implant and other indications were subsequently approved.

Pharmacokinetics
Goserelin is a synthetic analogue of a naturally occurring luteinising-hormone releasing hormone (LHRH). Bioavailability is almost complete. Gosereline is poorly protein bound and has a serum elimination half-life of two to four hours in patients with normal renal function. The half-life increases with patients with impaired renal function. There is no significant change in pharmacokinetics in subjects with hepatic failure. After administration, peak serum concentrations are reached in about two hours. It rapidly binds to the LHRH receptor cells in the pituitary gland thus leading to an initial increase in production of luteinizing hormone and thus leading to an initial increase in the production of corresponding sex hormones. This initial Flare may be treated by co-prescribing/co-administering Casodex (Bicalutamide) or similar medication. Eventually, after a period of about 14-21 days, production of LH is greatly reduced due to receptor downregulation, and sex hormones are generally reduced to castrate levels.

Indications
Goserelin Acetate is used to treat hormone-sensitive cancers of the prostate and breast (in pre-/perimenopausal women) and some benign gynaecological disorders (endometriosis, uterine fibroids and endometrial thinning). In addition, goserelin is used in assisted reproduction and in the treatment of precocious puberty. The syringe applicator comes with a protective sleeve, called the SafeSystem, to reduce and prevent needlestick injuries to administering healthcare professionals.

It is available as a 1-month depot and a long-acting 3-month depot. Both depots are used for the treatment of prostate cancer, endometriosis and uterine fibroids but only the 1-month depot is approved for breast cancer, endometrial thinning and assisted reproduction.

NOTE: The above license is probably from the USA. It should be noted that licensed indications may vary from country to country. For example, in the UK the 1-month depot is licensed for prostate cancer, endometriosis, uterine fibroids, breast cancer, endometrial thinning and assisted reproduction, and not as above. You are advised to consult a Healthcare Professional or your local regulatory authorities if you need more information on your local license for this product.

Side effects
Goserelin Acetate may cause a temporary increase in bone pain and symptoms of prostatic cancer during the first few weeks of treatment. As the body adjusts to the medication, the symptoms will disappear. Goserelin may cause hot flushes, headache, stomach upset, difficulty urinating (isolated cases), weight gain, swelling and tenderness of breasts (infrequent), decreased erections, reduced sexual desire. Bone pain can be managed symptomatically, and decreased libido can be treated by Levitra (Vardenifil) or other similar oral therapies.

Interactions
No known interaction with other medicinal products.

Effects on ability to drive and operate machinery
There is no evidence that Goserelin Acetate results in impairment of these activities.