(redirected from Antagon)


a synthetic compound derived from, and an antagonist to, gonadotropin-releasing hormone; used as the acetate salt to inhibit premature luteinizing hormone (LH) surges in women undergoing ovarian hyperstimulation in the treatment of female infertility, administered subcutaneously.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.


(ga-ni-rell-ix) ,


(trade name)


Therapeutic: hormones
Pregnancy Category: X


As a component of infertility regimens (with recombinant follicle stimulating hormone [FSH], and human chorionic gonadotropin) to inhibit premature luteinizing hormone (LH) surges in patients undergoing controlled ovarian hyperstimulation.


Induces a rapid, reversible suppression of gonadotropin (FSH and LH) secretion, which suppresses surges in LH. Ganirelix is a gonadotropin-releasing hormone antagonist.

Therapeutic effects

Suppression of LH surges increases the implantation and pregnancy rates in patients undergoing in vitro fertilization.


Absorption: Well absorbed following subcutaneous administration.
Distribution: 44 L.
Metabolism and Excretion: Metabolized to two primary metabolites; 18% excreted unchanged in urine.
Half-life: 16 hr.

Time/action profile (blood levels)

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Contraindicated in: Hypersensitivity to ganirelix, gonadotropin releasing hormone or any of its analogs; Obstetric: Known or suspected pregnancy.
Use Cautiously in: None noted.

Adverse Reactions/Side Effects


  • ovarian hyperstimulation syndrome (life-threatening)
  • abdominal pain
  • nausea


  • pelvic pain
  • vaginal bleeding


  • hypersensitivity reactions (life-threatening)
  • injection site reactions


Drug-Drug interaction



Subcutaneous (Adults) 250 mcg once daily during the mid-to-late follicular phase of menstrual cycle after initiating FSH on day 2 or 3 of cycle. Treatment with ganirelix should be continue daily until day of administration of human chorionic gonadotropin (when adequate follicular response achieved).


Injection: 250 mcg/0.5 mL in prefilled syringes

Nursing implications

Nursing assessment

  • Assess patient for pregnancy prior to therapy. Therapy should not be initiated if patient is pregnant.
  • Lab Test Considerations: May cause elevated neutrophil counts and decreased hematocrit and total bilirubin concentrations.

Potential Nursing Diagnoses

Deficient knowledge, related to medication regimen (Patient/Family Teaching)


  • Subcutaneous: Administer via subcutaneous injection only.

Patient/Family Teaching

  • Instruct patient on correct technique for subcutaneous injection. Most convenient sites are in the abdomen around the navel and in the upper thigh.

Evaluation/Desired Outcomes

  • Successful in vitro fertilization procedure.
Drug Guide, © 2015 Farlex and Partners
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