Ganirelix (Orgalutran)
Ganirelix Acetate (N-acetyl-3-(2-naphthyl)-D-alanyl-4-chloro-D-phenylalanyl-3-(3-pyridyl)-D-alanyl-L-seryl-L-tyrosyl-N9,N10-diethyl-D-homoarginyl-L-leucyl-N9,N10-diethyl-L-homoarginyl-L-prolyl-D-alanylamide acetate)
FDA-approved (1999) synthetic decapeptide GnRH antagonist used in IVF protocols to prevent premature LH surges during controlled ovarian stimulation, with the 0.25 mg daily regimen selected from dose-finding (PMID 9853849) and confirmed in Phase 3 RCTs (PMID 10875855, PMID 11278211) and Cochrane review (PMID 16855976).
Last updated: 2026-03-10
Safety Summary
The overall safety profile of ganirelix is well-established from two pivotal RCTs (N=794 ganirelix-treated subjects) and extensive post-marketing surveillance. FDA label Table IV lists adverse events at >=1% incidence without regard to causality, including fetal death (3.7%) which reflects the IVF population baseline rather than drug-attributable events. The most frequent drug-related events were abdominal pain (4.8%), headache (3.0%), OHSS (2.4%), vaginal bleeding (1.8%), injection site reaction (1.1%), and nausea (1.1%). Post-marketing pharmacovigilance identified shared signals with cetrorelix for OHSS-related events (ascites, pleural effusion, abdominal distension) that are attributable to the underlying infertility treatment rather than ganirelix specifically (PMC12016398). A 1000-fetus neonatal safety study found no increase in major malformations with ganirelix versus GnRH agonist protocols (5.0% vs 5.4%, OR 0.94, 95% CI 0.62-1.42) (PMID 20378616).
Known Side Effects
common
common
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common
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rare
common
Who Should NOT Use This
May cause fetal harm. Animal studies showed increased litter resorption in rats (doses up to 10 mcg/day) and rabbits (up to 30 mcg/day), approximately 0.4 to 3.2 times the human dose based on body surface area. No increase in fetal abnormalities, but the antigonadotropic effects could result in fetal loss. Pregnancy must be excluded before starting treatment.
Anaphylactoid/anaphylactic reactions reported during postmarketing surveillance, some with first dose.
Ganirelix should not be used by lactating women. It is not known whether ganirelix is excreted in human milk.
Pharmacokinetics have not been determined in renally or hepatically impaired patients. Use with caution.
Talk to Your Doctor
Before considering Ganirelix (Orgalutran), discuss it with your healthcare provider. Ask about potential interactions with your current medications, whether it is appropriate for your health conditions, and what monitoring may be needed.
Sources: [1-14]
Evidence Assessment
Tier 1 -- FDA-approved since 1999 (NDA 21057). The label cites two adequate and well-controlled clinical studies. Supported by a Phase 2 dose-finding RCT of 332 patients (PMID 9853849), a pivotal Phase 3 trial of 463 patients (PMID 10875855), a randomized multicenter comparison versus triptorelin (PMID 11278211, n=355), and a Chinese multicenter RCT (PMID 22429192, n=233). A Cochrane systematic review of 27 RCTs (PMID 16855976) and a separate meta-analysis of 22 RCTs (PMID 16920869) confirm efficacy with comparable or slightly lower pregnancy rates offset by significantly reduced OHSS risk. Long-term neonatal safety established in a 1000-fetus follow-up study (PMID 20378616). Standard of care in IVF clinics worldwide with international guideline support.
1A double-blind, randomized, dose-finding study to assess the efficacy of the gonadotrophin-releasing hormone antagonist ganirelix (Org 37462) to prevent premature luteinizing hormone surges in women undergoing ovarian stimulation with recombinant follicle stimulating hormone (Puregon)PMID 9853849
Ganirelix Dose-Finding Study Group - Human Reproduction (1998) - Phase 2 RCT (double-blind, multicenter, dose-finding) - 332 patients treated (333 enrolled per abstract)
Established 250 mcg/day as optimal dose. Vital pregnancy rate 35.7% per attempt, 40.3% per transfer at 250 mcg (FDA label Table II). Ongoing pregnancy rate 33.8% per attempt at 12-16 weeks. Implantation rate 21.9%. LH surges >=10 mIU/mL in only 1.4% at 250 mcg vs 16% at 0.0625 mg. Lowest (0.0625 mg) and highest (2.0 mg) dose groups terminated early on advisory committee recommendation.
Limitations: Industry-sponsored (Organon). Dose-comparison design rather than placebo-controlled. Open-label at extremes of dosing.
2Treatment with the gonadotrophin-releasing hormone antagonist ganirelix in women undergoing ovarian stimulation with recombinant follicle stimulating hormone is effective, safe and convenient: results of a controlled, randomized, multicentre trialPMID 10875855
Borm G, Mannaerts B (European Orgalutran Study Group) - Human Reproduction (2000) - Phase 3 RCT (open-label, multicenter, non-inferiority) - 730
Ganirelix (n=487) vs buserelin long protocol (n=243). Ongoing PR per attempt: 20.3% ganirelix vs 25.7% buserelin. Implantation rate 15.7% vs 21.8%. Median ganirelix treatment 5 days vs 26 days buserelin. Median rFSH 1500 IU vs 1800 IU. OHSS incidence 2.4% ganirelix vs 5.9% buserelin. Fertilization rates equal (62.1%). Mean oocytes 9.1 vs 10.4.
Limitations: Open-label design. Non-inferiority margin not pre-specified in publication. Pregnancy rates numerically lower with ganirelix though offset by safety advantages. Manufacturer-sponsored (Organon).
3Comparable clinical outcome using the GnRH antagonist ganirelix or a long protocol of the GnRH agonist triptorelin for the prevention of premature LH surges in women undergoing ovarian stimulationPMID 11278211
European/Middle East Orgalutran Study Group - Human Reproduction (2001) - Phase 3 RCT (multicenter, randomized) - 355
Ganirelix (n=236) vs triptorelin long protocol (n=119). Ongoing PR per attempt: 31.0% vs 33.9%. Implantation rate identical (22.9%). Treatment 17 days shorter with ganirelix (9 vs 26 days). 450 IU less rFSH used. 2-fold fewer injection site reactions (11.9% vs 24.1%). Fertilization rates comparable (64.0% vs 64.9%).
Limitations: 2:1 randomization ratio limits statistical power for superiority testing. Open-label design. Manufacturer-sponsored.
4Pharmacokinetic and pharmacodynamic characteristics of ganirelix (Antagon/Orgalutran). Part I. Absolute bioavailability of 0.25 mg of ganirelix after a single subcutaneous injection in healthy female volunteersPMID 10593371
Oberye JJ, Mannaerts BM, Kleijn HJ, Timmer CJ - Fertility and Sterility (1999) - Phase 1 PK study (randomized crossover) - 15 evaluable (19 enrolled)
Mean absolute bioavailability after SC injection: 91.3% +/- 6.7%. Cmax SC: 14.8 +/- 3.2 ng/mL. Tmax SC: 1.1 +/- 0.3 hours. Half-life: 12.8 +/- 4.3 h (SC), 12.7 +/- 3.7 h (IV). AUC SC: 96 +/- 12 ng*h/mL, IV: 105 +/- 11 ng*h/mL. Vd (IV): 43.7 +/- 11.4 L.
Limitations: Small sample size (n=15). Healthy volunteers only. Manufacturer-sponsored.
5Pharmacokinetic and pharmacodynamic characteristics of ganirelix (Antagon/Orgalutran). Part II. Dose-proportionality and gonadotropin suppression after multiple doses of ganirelix in healthy female volunteersPMID 10593372
Oberye JJ, Mannaerts BM, Huisman JA, Timmer CJ - Fertility and Sterility (1999) - Phase 1 PK/PD study (randomized, parallel) - 45
Dose-proportional PK (0.125-0.50 mg range). Steady state in 2-3 days. At 0.25 mg x7 days: LH maximally decreased 74% (4h), FSH 32% (16h), E2 25% (16h). Serum levels returned to pretreatment within 2 days of last injection. Cmax at steady state: 11.2 ng/mL (0.25 mg).
Limitations: Small groups (n=15 per dose). Healthy volunteers, not IVF patients. Manufacturer-sponsored.
6Gonadotrophin-releasing hormone antagonists for assisted conception (Cochrane Review)PMID 16855976
Al-Inany HG, Abou-Setta AM, Aboulghar M - Cochrane Database of Systematic Reviews (2006) - Systematic review and meta-analysis - 27 RCTs
GnRH antagonist vs long agonist protocol: CPR significantly lower (OR 0.84, 95% CI 0.72-0.97). OPR/LBR also lower (OR 0.82, 95% CI 0.69-0.98). However, severe OHSS significantly reduced (RR 0.61, 95% CI 0.42-0.89). Less gonadotropin consumption. Shorter treatment duration.
Limitations: Heterogeneity in protocols across included trials. Earlier RCTs may reflect learning curve with antagonist protocols. Later updates showed narrowing of pregnancy rate gap.
7Among patients treated for IVF with gonadotrophins and GnRH analogues, is the probability of live birth dependent on the type of analogue used? A systematic review and meta-analysisPMID 16920869
Kolibianakis EM, Collins J, Tarlatzis BC, Devroey P, Diedrich K, Griesinger G - Human Reproduction Update (2006) - Systematic review and meta-analysis - 22 RCTs, 3176 subjects
No significant difference in live birth probability between GnRH antagonist and agonist suppression (OR 0.86, 95% CI 0.72-1.02). Result stable across all subgroup analyses (population type, gonadotropin type, agonist type, antagonist type, allocation concealment).
Limitations: Some live birth data converted from ongoing pregnancy using published conversion factors. Pooled all antagonist types (not ganirelix-specific).
8A randomized controlled trial of the GnRH antagonist ganirelix in Chinese normal responders: high efficacy and pregnancy ratesPMID 22429192
Qiao J, Lu G, Zhang HW et al. - Gynecological Endocrinology (2012) - Phase 3 RCT (multicenter, open-label) - 233
Ganirelix (n=113) vs triptorelin long protocol (n=120). Ongoing PR per started cycle: 39.8% vs 39.2%. Significantly less rFSH needed (1272 IU vs 1416 IU, P<0.001). OHSS cancellation less frequent with ganirelix (1.8% vs 7.5%, P=0.06).
Limitations: Open-label design. Chinese population may not be generalizable to all ethnicities. Relatively small sample size.
9Endocrine profiles after triggering of final oocyte maturation with GnRH agonist after cotreatment with the GnRH antagonist ganirelix during ovarian hyperstimulation for in vitro fertilizationPMID 11836309
Fauser BC, de Jong D, Olivennes F et al. - Journal of Clinical Endocrinology and Metabolism (2002) - Phase 2 RCT (multicenter, randomized) - 47
GnRH agonist trigger (triptorelin 0.2 mg or leuprorelin 0.5 mg) effectively induced oocyte maturation after ganirelix co-treatment. LH peaked at 130 and 107 IU/L at 4h. Oocytes retrieved: 9.8, 8.7, 8.3 (triptorelin, leuprorelin, hCG). Metaphase II rates: 72%, 85%, 86%. Fertilization rates comparable across groups. Luteal steroid levels closer to physiological range with agonist triggers.
Limitations: Small sample size (n=47). Pilot/proof-of-concept. Pregnancy outcomes not adequately powered.
10Large prospective, pregnancy and infant follow-up trial assures the health of 1000 fetuses conceived after treatment with the GnRH antagonist ganirelix during controlled ovarian stimulationPMID 20378616
Bonduelle M, Oberye J, Mannaerts B, Devroey P - Human Reproduction (2010) - Prospective cohort with historical control - 839 pregnancies (969 live births) vs 753 control pregnancies (963 live births)
Major congenital malformation rate (fetuses >=26 weeks): 5.0% ganirelix vs 5.4% historical GnRH agonist (OR 0.94, 95% CI 0.62-1.42). No relevant differences in pregnancy/delivery complications. More singletons in ganirelix group (81.3% vs 68.1%).
Limitations: Historical comparator rather than concurrent randomized control. Single-center follow-up. Differences in multiple pregnancy rates between groups. Manufacturer-sponsored.
11Prospective, randomized trial comparing cetrorelix acetate and ganirelix acetate in a programmed, flexible protocol for premature luteinizing hormone surge prevention in assisted reproductive technologiesPMID 16009165
Wilcox J, Potter D, Moore M, Ferrande L, Kelly E - Fertility and Sterility (2005) - RCT (prospective, open-label, multicenter) - 185
No patient in either cetrorelix (3 mg single-dose) or ganirelix (0.25 mg daily) group had a premature LH surge. No statistically significant differences in any IVF/ICSI outcome. Cetrorelix required fewer injections. Similar safety profiles.
Limitations: Open-label design. Relatively small sample size. Single-dose cetrorelix vs daily ganirelix complicates direct comparison.
12What is the optimal GnRH antagonist protocol for ovarian stimulation during ART treatment? A systematic review and network meta-analysisPMID 36594696
Venetis CA, Storr A, Chua SJ et al. - Human Reproduction Update (2023) - Systematic review and network meta-analysis - 102 publications (75 unique studies), 73 in meta-analysis
Fixed Day 5/6 antagonist protocol had significantly higher OPR than flexible protocol (RR 0.76 for flexible, 95% CI 0.62-0.94). OCP pretreatment associated with lower OPR vs no pretreatment (RR 0.79, 95% CI 0.69-0.92). Fixed protocol with no pretreatment most likely (84% SUCRA) to yield highest OPR. Insufficient data for ganirelix vs cetrorelix comparison.
Limitations: Most included studies were low quality. Lack of live birth data for key comparisons. Mostly low-certainty evidence.
13Ganirelix (Drug Review)PMID 10718102
Gillies PS, Faulds D, Balfour JA, Perry CM - Drugs (2000) - Drug review/monograph - N/A (review)
Comprehensive review characterizing ganirelix as a third-generation GnRH antagonist with reduced histamine-releasing properties. Vital pregnancy rate 40.3% per embryo transfer at 0.25 mg/day. Documents receptor binding affinity, metabolic stability, and amino acid substitution rationale.
Limitations: Narrative review, not systematic. Based on early clinical trial data available at launch.
14Medroxyprogesterone acetate versus ganirelix in oocyte donation: a randomized controlled trialNCT02796105PMID 30927417
Begueria R, Garcia D, Vassena R, Rodriguez A - Human Reproduction (2019) - RCT (open-label, single-center, non-inferiority) - 173 donors (86 MPA, 87 ganirelix); 252 recipients
MII oocytes: 15.1 (MPA) vs 14.6 (ganirelix) -- non-inferior. But recipient reproductive outcomes unexpectedly lower with MPA: ongoing PR 27% vs 40% (P=0.015), clinical PR 31% vs 46% (P=0.006). Duration and gonadotropin dose similar between groups.
Limitations: Recipients not randomized (non-inferiority designed for donor MII). Single center. Unexpected findings in reproductive outcomes require further investigation.