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Ganirelix: controlling ovulation during assisted reproduction

Clinical review pending

Ganirelix prevents a premature LH surge during controlled ovarian stimulation. How it works, when it is used and its possible side effects.

What is ganirelix?

Ganirelix acetate is a synthetic peptide containing ten amino acids and an antagonist at the GnRH receptor. Originally approved under the name Antagon, it is sold as Orgalutran in some regions. During assisted reproduction, it helps control the timing of ovulation. It was developed under the code Org 37462 and received US approval in 1999. According to the source article, it is now available in the United States as ganirelix acetate injection and under the name Fyremadel 1.

How does ganirelix work?

Ganirelix competitively blocks GnRH receptors in the pituitary gland, rapidly suppressing the release of luteinizing hormone and follicle-stimulating hormone. During IVF treatment, injected hormones stimulate the ovaries to mature several follicles. If the body’s luteinizing hormone rises too early, ovulation can occur before the planned egg retrieval. Ganirelix prevents this premature surge during stimulation. Source

As an antagonist, ganirelix acts immediately and reversibly. This allows shorter, more flexible treatment protocols than older agonist approaches, which first required pituitary suppression over several days. A North American phase 3 trial compared ganirelix with a long leuprolide protocol; the results appear in the table.

Is ganirelix FDA-approved?

Developed by Organon, ganirelix was approved by the FDA in 1999 3. The source article describes a daily subcutaneous dose of 0.25 mg during controlled ovarian stimulation. The Antagon brand name is no longer used in the United States; the medicine is offered there as ganirelix acetate injection and as Fyremadel.

What is ganirelix prescribed for?

Ganirelix prevents a premature luteinizing hormone surge in women undergoing controlled ovarian stimulation as part of assisted reproduction. It is used only during this phase of the treatment cycle.

What side effects are possible?

The prescribing information linked in the source article 4 lists the following common side effects:

  • Injection-site reactions

  • Headaches

  • Nausea

  • Abdominal or pelvic discomfort

Other important risks include:

  • Ovarian hyperstimulation syndrome: this is a risk of the overall stimulation treatment, rather than a risk specific to ganirelix alone.

  • Hypersensitivity reactions

Ganirelix is contraindicated during pregnancy.

Studies at a glance

Endpoint Ganirelix compared with the long leuprolide protocol
Ongoing pregnancy rate Comparable [2]
Number of injections Lower
Injection-site reactions Less frequent

Source

References provided in the source article

Sources: FDA prescribing information for ganirelix acetate injection; the North American phase 3 trial (Fluker et al., Fertility and Sterility, 2001, DOI: 10.1016/s0015-0282(00)01638-1 2 ), indexed on PubMed.

Provenance and editorial review status

Adapted for Nutrient Desk from the source article. The claims and source attributions in the original text still require clinical review. This draft has not been cleared for indexing.