Evidence Grade A — Regulatory approved. 188 published studies. 82 registered clinical trials.
Medically reviewed by a licensed medical professional
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Ganirelix (originally sold as Antagon) is an injectable medication used during IVF to prevent premature ovulation, ensuring eggs can be collected at the optimal time. It was the first GnRH antagonist approved in the US for fertility treatment and comes in a convenient prefilled syringe for daily self-injection. In clinical practice, it is considered interchangeable with cetrorelix.
Ganirelix is also known by these brand and alternate names:
188 published studies: 159 human, 8 animal, 62 in-vitro, 21 reviews
Ganirelix was originally marketed as Antagon (approved July 1999), making it the first GnRH antagonist approved in the US. It is indicated for prevention of premature LH surges during controlled ovarian stimulation, administered as a daily 250 mcg subcutaneous injection starting mid-cycle.
In clinical practice, ganirelix and cetrorelix are considered therapeutically equivalent, with fertility clinic preference often determined by practical factors such as prefilled syringe convenience, local availability, and cost. Both have been instrumental in the shift from longer GnRH agonist protocols to the shorter, safer antagonist protocols that now dominate IVF practice worldwide.
Ganirelix works identically to cetrorelix — it directly blocks the GnRH receptor in the pituitary gland to prevent the premature LH surge that would trigger ovulation before eggs are ready for collection during IVF. It provides immediate suppression of LH (approximately 74% reduction within four hours of injection) with rapid reversibility once stopped. The practical difference from cetrorelix is primarily in formulation: ganirelix comes as a ready-to-use prefilled syringe, while cetrorelix requires reconstitution.
Ganirelix and cetrorelix are clinically equivalent — no head-to-head trials have shown meaningful differences in pregnancy rates or safety between them. The choice is typically driven by formulary availability, cost, and practical factors like prefilled syringe convenience versus the need for reconstitution. Together, these two drugs helped shift IVF practice worldwide from longer GnRH agonist protocols to shorter antagonist protocols that reduce the risk of ovarian hyperstimulation syndrome and require fewer injections. Generic ganirelix has improved affordability and access. No major new research programmes are active for ganirelix specifically.
PeptideTrace tracks 82 registered clinical trials for Ganirelix sourced from ClinicalTrials.gov.
Is the Diurnal Variation in Circulating Levels of Cortisol Reflected in Follicular Fluid of Preovulatory Follicles Close to Ovulation?
IVF Outcomes With Time-Lapse Culture: Comparison Between PPOS and GnRH Antagonist Protocols
hCG Priming in Women With Diminished Ovarian Reserve
PPOS (Progestin Primed Ovarian Stimulation) and Corifollitropin Alfa (CFA) Cross-over Study
Disentangling the Effects of Daily Stress, Sleep, and Sex Hormones on Accelerated Vascular Aging in Midlife Women
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Ganirelix is a synthetic decapeptide (10 amino acids) GnRH antagonist and was the first GnRH antagonist approved in the United States. It is formulated as a ready-to-use prefilled syringe for subcutaneous injection.
Ganirelix competitively antagonizes the GnRH receptor, suppressing LH by approximately 74% within 4 hours of administration. Like cetrorelix, it provides rapid-onset, rapidly reversible gonadotropin suppression without initial hormonal flare. The effects dissipate within 48 hours, allowing for precise timing of ovulation trigger in IVF cycles.
Ganirelix was originally marketed as Antagon (approved July 29, 1999—the first GnRH antagonist in the US). Indicated for inhibition of premature LH surges in women undergoing controlled ovarian hyperstimulation. Available as a prefilled syringe (250 mcg/0.5 mL) for daily subcutaneous injection starting mid-stimulation. Functionally interchangeable with cetrorelix in clinical practice.
Carbetocin has not been approved by the FDA. It is registered in over 80 countries for prevention of uterine atony and excessive bleeding after caesarean delivery. A heat-stable formulation was added to the WHO Essential Medicines List in 2019. The CHAMPION trial (WHO, 2018; over 29,000 women) compared a heat-stable carbetocin formulation to oxytocin for preventing postpartum haemorrhage after vaginal delivery, and found it to be non-inferior. The heat-stable formulation addresses a significant limitation of oxytocin, which degrades in warm climates without refrigeration — a major concern in low-resource settings where postpartum haemorrhage causes the most deaths. Its regulatory status varies by jurisdiction.
Kisspeptin-54 has no marketing authorisation. Phase II trials conducted primarily at Imperial College London have investigated its use as an IVF oocyte maturation trigger. One trial (60 patients) reported 95% oocyte maturation with zero cases of ovarian hyperstimulation syndrome. Kisspeptin-54 has a more advanced clinical evidence base than kisspeptin-10, with multiple Phase II studies in reproductive medicine. Its potential advantage over conventional IVF triggers relates to a lower risk of the serious complication of ovarian hyperstimulation. Clinical development is ongoing in academic settings. No Phase III trials have been completed.
Goserelin is marketed as Zoladex by AstraZeneca, available as 3.6 mg monthly and 10.8 mg three-monthly subcutaneous implants. First approved in 1989, it is used in advanced prostate cancer, premenopausal breast cancer, endometriosis, and for thinning the uterine lining before surgical procedures. Goserelin achieves castrate-level testosterone suppression (below 50 ng/dL) within two to four weeks. Its unique implant delivery system means there is no liquid injection, reconstitution, or refrigeration required — a practical advantage in some clinical settings. Like all GnRH agonists, it causes an initial hormone flare before suppression takes effect. Goserelin holds an important niche in breast cancer treatment, where it is used to suppress ovarian function in premenopausal women with hormone-receptor-positive disease, often in combination with aromatase inhibitors.
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