Ganirelix Brand Name– Antagon | Ganirelix

What is Ganirelix

Ganirelix is a gonadotropin-releasing hormone (GnRH) antagonist. It is indicated for inhibiting premature leuteinizing hormone (LH) surges in women undergoing controlled ovarian hyperstimulation with FSH and HCG, followed by subsequent assisted insemination or reproductive technology (ART) procedures.

The main advantage of GnRH antagonists versus GnRH agonists (e.g., leuprolide) is that they reduce the required days of fertility drug therapy per cycle from several weeks (i.e., 3 weeks) to several days, thereby increasing patient convenience.

Secondarily, the onset of GnRH antagonists occurs rapidly after drug initiation, and the effects reverse rapidly, allowing pituitary function to return to baseline within about 2 days after discontinuation.

Thus, pituitary and hormonal release is essentially normalized at the time of embryo transfer or implantation. It was theorized that these properties would improve embryo viability and pregnancy success rates; however, results from meta-analyses comparing GnRH antagonists to GnRH agonists do not support this theory.

One meta-analysis found that there were no differences in live births between the 2 treatment modalities and a second meta-analysis found a lower rate of pregnancy in patients receiving GnRH antagonists along with a lower rate of live births.

In terms of safety, both meta-analyses found a significantly lower rate of ovarian hyperstimulation syndrome (OHSS) in protocols using GnRH antagonists as well as a lower rate of severe OHSS, including hospitalization.

Protocols utilizing GnRH antagonists versus GnRH agonists are simple and short, possibly with a lower risk of OHSS; additionally, most studies have found that gonadotropin requirements are lower.

Ganirelix was the first GnRH antagonist FDA-approved in the United States in 1999.


  • infertility

For inhibiting premature leutenizing hormone (LH) surges in women undergoing controlled ovarian hyperstimulation as part of the treatment of infertility

Side Effects

  1. abdominal pain
  2. anaphylactoid reactions
  3. antibody formation
  4. fetal death
  5. headache
  6. hot flashes
  7. injection site reaction
  8. menstrual irregularity
  9. nausea
  10. ovarian enlargement
  11. ovarian hyperstimulation syndrome (OHSS)
  12. pelvic pain
  13. pruritus
  14. teratogenesis
  15. vaginal bleeding

Monitoring Parameters

  • pelvic exam
  • pelvic ultrasound
  • serum estradiol concentrations
  • serum gonadotropin concentrations
  • weight


  • breast-feeding
  • children
  • geriatric
  • Gonadotropin-Releasing Hormone (GnRH) analogs hypersensitivity
  • hepatic disease
  • latex hypersensitivity
  • ovarian cyst
  • ovarian failure
  • polycystic ovary syndrome
  • pregnancy
  • renal impairment
  • requires an experienced clinician
  • serious hypersensitivity reactions or anaphylaxis
  • tobacco smoking


  • Aripiprazole
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  • atypical antipsychotic
  • Brexpiprazole
  • Cariprazine
  • Cimetidine
  • Clozapine
  • Fluoxetine; Olanzapine
  • Haloperidol
  • Iloperidone
  • Loxapine
  • Lumateperone
  • Lurasidone
  • Molindone
  • Olanzapine
  • Paliperidone
  • Phenothiazines
  • Pimozide
  • Prasterone, Dehydroepiandrosterone, DHEA (Dietary Supplements)
  • Prasterone, Dehydroepiandrosterone, DHEA (FDA-approved)
  • Quetiapine
  • Risperidone
  • Tetrabenazine
  • Thiothixene
  • Ziprasidone
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