Ganirelix
Also known as: Ganirelix acetate, Orgalutran, Fyremadel, Org 37462
Key Facts: Ganirelix
- Category
- Hormonal
- FDA Status
- FDA Approved
- Clinical Status
- FDA Approved - Ganirelix acetate injection 250 mcg/0.5 mL (NDA 021057, approved July 29, 1999; Organon), plus generic versions including Fyremadel. Sold as Orgalutran in Europe. Indicated for inhibition of premature LH surges in women undergoing controlled ovarian hyperstimulation.
- Banned in Sport (WADA)
- Not on the WADA Prohibited List (2026). S2 bans GnRH and its agonist analogues in males, but antagonists like ganirelix are not listed, and as an approved drug it is not caught by S0.
- Administration
- Subcutaneous injection from a prefilled syringe
- Typical Dose
- 250 mcg once daily during IVF stimulation (labeled dose)
- Frequency
- Once daily
- Duration
- A few days per IVF cycle (mean 5.4 days in trials, range 2-14)
How does Ganirelix work?
Ganirelix is a modified version of GnRH with six amino-acid swaps that turn it into a receptor blocker. It competitively blocks GnRH receptors on the pituitary, causing a fast, reversible drop in LH (and to a lesser extent FSH) without the initial hormone flare that GnRH agonists cause. That lets clinics start it mid-cycle, usually around day 6 of FSH injections, to prevent a premature LH surge. Pituitary LH and FSH fully recover within 48 hours of stopping. Its half-life is about 13 hours after one dose and 16 hours with daily use, so once-daily injections keep the block steady. In men the same block lowers testosterone.
What does the research show?
Two well-controlled trials supported approval. A double-blind dose-finding study in 332 women tested 62.5 to 2,000 mcg and found 250 mcg gave the best pregnancy and implantation rates (higher doses over-suppressed estrogen and lowered pregnancy rates). An open-label trial of 463 women on 250 mcg daily saw premature LH surges in under 1%, with an ongoing pregnancy rate of about 20% per attempt. The North American phase 3 trial (Fluker and colleagues, 2001, 313 women) compared ganirelix with a long leuprolide protocol: slightly fewer eggs (11.6 vs 14.1) and numerically lower pregnancy rates, but shorter treatment, fewer injections and fewer injection site reactions. The 2016 Cochrane review of 73 trials across GnRH antagonists found live birth rates similar to the long agonist protocol with clearly less ovarian hyperstimulation syndrome. One honest note: the label's adverse event table lists fetal death at 3.7%, which reflects early pregnancy loss in IVF patients generally, not a proven drug effect, and a follow-up of over 1,000 newborns found congenital anomaly rates comparable to agonist-treated cycles.
FDA Approval Studies
This peptide is FDA approved. Below are the key clinical trials that supported its approval.
Ganirelix dose-finding study and Protocol 38607
Organon • Phase 2/3
332 women (dose-finding) and 463 women (open-label efficacy study)
One controlled ovarian hyperstimulation cycle
Prevention of premature LH surge; pregnancy and implantation rates
- ✓250 mcg gave the highest pregnancy and implantation rates of doses from 62.5 to 2,000 mcg
- ✓Premature LH surge in under 1% of 463 women on 250 mcg
- ✓Ongoing pregnancy rate 20.3% per attempt
- ✓Mean 5.4 days of treatment
What doses have been studied?
Typical Dosingⓘ
Community experience
250 mcg once daily during IVF stimulation (labeled dose)
250 mcg daily
Once daily
Labeled prescription dose, used only inside a monitored IVF cycle with FSH and ultrasound tracking. Higher doses were not better in the dose-finding trial. Use outside fertility treatment has no established benefit.
Research Dosingⓘ
Scientific studies
FDA-approved labeled dosing (prescription only, used within an IVF cycle)
Doses from Studies
250 mcg once daily until hCG
FDA Approved Labeling - Ganirelix acetate injection prescribing information ↗
62.5-2,000 mcg tested; 250 mcg best pregnancy rates
Phase 2 dose-finding trial - Double-blind dose-finding study, Human Reproduction 1998 ↗
250 mcg daily vs long leuprolide protocol
Phase 3 trial - Fluker et al., Fertility and Sterility 2001 ↗
Duration
A few days per IVF cycle (mean 5.4 days in trials, range 2-14)
Administration
Subcutaneous injection from a prefilled syringe
When and how is Ganirelix taken?
Best Time to Take
Same time each day, usually starting around day 6 of FSH
Once daily until the day of the hCG trigger
Food Recommendation
With or without food
Why This Timing?
The pivotal trials gave it in the morning from day 6 of FSH stimulation; steady once-daily dosing keeps LH suppressed until the trigger shot.
What are the side effects of Ganirelix?
Not everyone experiences these effects. Individual responses vary based on dosage, duration, and personal factors.
- ●Pelvic or abdominal pain (4.8%)
- ●Headache (3%)
- ●Ovarian hyperstimulation syndrome (2.4%, tied to the overall IVF stimulation)
- ●Vaginal bleeding
- ●Injection site reactions
- ●Nausea
- ●Rare hypersensitivity reactions, including anaphylaxis, sometimes with the first dose
- ●Contraindicated in pregnancy
- ●Suppresses LH and testosterone in men (not an anabolic)
References
- https://www.lupin.com/US/uploads/pi_ganirelix_acetate_injection_10_2024_2_4918247095.pdf
- https://pubmed.ncbi.nlm.nih.gov/9853849/
- https://pubmed.ncbi.nlm.nih.gov/11163814/
- https://pubmed.ncbi.nlm.nih.gov/27126581/
- https://www.drugs.com/pro/ganirelix.html
Research This Peptide Further
Frequently Asked Questions
What does Ganirelix do?
Ganirelix is a GnRH antagonist used in IVF to stop the body from ovulating too early while the ovaries are being stimulated. The FDA approved it in July 1999 (originally from Organon, now also sold as generics such as Fyremadel), and it comes as a ready-to-use 250 mcg prefilled syringe. It does the same job as cetrorelix, with a slightly longer half-life. It is a boring, reliable fertility drug, and that is a compliment.
How does Ganirelix work?
Ganirelix is a modified version of GnRH with six amino-acid swaps that turn it into a receptor blocker. It competitively blocks GnRH receptors on the pituitary, causing a fast, reversible drop in LH (and to a lesser extent FSH) without the initial hormone flare that GnRH agonists cause. That lets clinics start it mid-cycle, usually around day 6 of FSH injections, to prevent a premature LH surge. Pituitary LH and FSH fully recover within 48 hours of stopping. Its half-life is about 13 hours after one dose and 16 hours with daily use, so once-daily injections keep the block steady. In men the same block lowers testosterone.
Is Ganirelix FDA approved?
Yes, Ganirelix is FDA approved. FDA Approved - Ganirelix acetate injection 250 mcg/0.5 mL (NDA 021057, approved July 29, 1999; Organon), plus generic versions including Fyremadel. Sold as Orgalutran in Europe. Indicated for inhibition of premature LH surges in women undergoing controlled ovarian hyperstimulation.
Is Ganirelix banned in sport?
Not on the WADA Prohibited List (2026). S2 bans GnRH and its agonist analogues in males, but antagonists like ganirelix are not listed, and as an approved drug it is not caught by S0.
What are the side effects of Ganirelix?
Reported side effects include: Pelvic or abdominal pain (4.8%), Headache (3%), Ovarian hyperstimulation syndrome (2.4%, tied to the overall IVF stimulation), Vaginal bleeding, Injection site reactions. Individual responses vary based on dosage, duration, and personal health factors.
What is the typical dose of Ganirelix?
Community-reported common dose: 250 mcg once daily during IVF stimulation (labeled dose) (Once daily). Range: 250 mcg daily. Administration: Subcutaneous injection from a prefilled syringe. Prescription drug. Dose set by prescriber per label. Not medical advice.
Related Peptides
Peptides commonly compared with Ganirelix or used in similar applications.
Leuprolide
FDALeuprolide (brand name Lupron) is a synthetic GnRH agonist, a modified peptide far more potent than natural GnRH, and it is FDA-approved for advanced prostate cancer, endometriosis, uterine fibroids, and central precocious puberty. The clever part is counterintuitive: it works by overstimulating the GnRH system so hard that the pituitary shuts down sex hormone production. It is a real, long-established prescription drug (first US approval 1985), not a research peptide, and it carries meaningful side effects from the low-hormone state it creates.
HormonalOctreotide
FDAOctreotide is a synthetic eight-amino-acid mimic of the natural hormone somatostatin, the body's main 'off switch' for hormone secretion. It shuts down excess growth hormone, so it is a frontline FDA-approved drug for acromegaly, and it also tames the flushing and diarrhea of hormone-secreting carcinoid and other neuroendocrine tumors. This is real, approved medicine with decades of clinical data behind it, sold as Sandostatin (injectable, since 1988), Sandostatin LAR (monthly depot), and Mycapssa (oral capsule, approved 2020).
HormonalLanreotide
FDALanreotide (development code BIM-23014) is an eight-amino-acid somatostatin analog, a close cousin of octreotide, given as a long-acting deep-injection gel (Somatuline Depot/Autogel) usually once a month. The FDA approved it for acromegaly in 2007, for gastroenteropancreatic neuroendocrine tumors in 2014, and for carcinoid syndrome in 2017. Generic versions now exist alongside Ipsen's Somatuline Depot. It is established prescription medicine, not an experimental compound.
HormonalPegvisomant
FDAPegvisomant (brand name Somavert) flips the usual acromegaly strategy on its head: instead of telling the tumor to make less growth hormone, it blocks growth hormone's receptor on target tissues directly. It is a PEGylated, genetically modified version of human growth hormone that acts as a receptor antagonist, FDA-approved in 2003 for acromegaly patients who do not respond well to surgery or other drugs. It is the single most effective option for normalizing IGF-1, which is why it is a key second-line therapy.
HormonalMacimorelin
FDAMacimorelin (brand name Macrilen) is an orally active ghrelin receptor agonist used as a diagnostic test, not a treatment. You drink a single dose, then doctors measure how much growth hormone the pituitary releases to diagnose adult growth hormone deficiency. It was FDA approved in December 2017 as the first oral diagnostic agent for that condition.
HormonalHMG
FDAHMG (human menopausal gonadotropin, sold as menotropins under the brand Menopur) is a purified hormone mix extracted from the urine of postmenopausal women. Each standard vial carries 75 IU of FSH activity and 75 IU of LH activity, with most of the LH activity coming from hCG. It is an FDA-approved fertility drug used to stimulate egg development in IVF, and it is also used, mostly off-label in the US, together with hCG to kick-start sperm production in men whose pituitary does not make enough FSH and LH. This one has decades of real clinical use behind it.
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