Ganirelix

Ganirelix is a prescription drug used to improve fertility in women undergoing controlled ovarian hyperstimulation. Chronic ovarian hyperstimulation uses drugs to increase the production of mature follicles and eggs to increase the chances of a pregnancy. Ganirelix suppresses the release of luteinizing hormone and follicle stimulating hormone. The U.S. Food and Drug Administration approved ganirelix in July 1999.

Other Names

Ganirelix is marketed by Organon under the brand name Antagon.

Uses

Ganirelix is used to inhibit premature luteinizing hormone (LH) surges in women undergoing controlled ovarian hyperstimulation.

How Ganirelix is Taken

Ganirelix is supplied at a concentration of 250 μg (micrograms)/0.5 ml.

Controlled ovarian hyperstimulation uses follicle stimulating hormone (FSH) to stimulate production of follicles and eggs. The follicles can be used in in vitro fertilization. Ganirelix is injected subcutaneously (under the skin) once daily during the early to mid follicular phase of the menstrual cycle, after initiating FSH therapy on day 2 or 3 of the menstrual cycle.

How Ganirelix Works

Sometimes LH levels surge in women undergoing controlled ovarian hyperstimulation. This increase in LH levels can cause premature rupture of follicles and the premature release of an egg. The release of LH and FSH from the pituitary gland is stimulated by gonadotropin releasing hormone (GnRH). Ganirelix blocks GnRH receptors in the pituitary gland and prevent the release of LH and FSH.

How the Body Affects Ganirelix

After administration, ganirelix is rapidly absorbed with peak circulating levels reached within approximately one hour. Ganirelix concentrations in blood become steady after three days of treatment. Ganirelix is primarily excreted in the feces.

Side Effects

The most common side effects of ganirelix, which occur in 1% or more of women, are the following:

• abdominal pain (gynecological or gastrointestinal)
• miscarriage
• headache
• ovarian hyperstimulation syndrome
• vaginal bleeding
• injection-related reaction
• nausea

Risks and Precautions

The safety of ganirelix has not been determined in pregnant or nursing women. Accordingly, some risk to a pregnancy or infant may exist.

Drug Interactions

No significant interactions have been reported with Ganirelix at this time.

Research

One study showed that treatment with either leuprolide or ganirelix had similar fertilization rates (62%).^[1] Ongoing pregnancy rates per attempt were 31% and 36% for women treated with ganirelix or euprolide respectively.

References

1. ↑ Fluker M, Grifo J, Leader A, et al. Efficacy and safety of ganirelix acetate versus leuprolide acetate in women undergoing controlled ovarian hyperstimulation. Fertil Steril. 2001 Jan;75(1):38-45. Abstract