Hormonal & reproductive

Cetrorelix

Also called Cetrotide, cetrorelix acetate

Cetrorelix (brand name Cetrotide) is a lab-made peptide that blocks the brain signal that triggers ovulation. Fertility clinics use it during IVF so that eggs are not released too early, before they can be collected. It is FDA-approved for this single use, and generic versions have also been approved in the US.

FDA-approvedApproved by the FDA for at least one use after large human trials.

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Illustrative chain. The exact sequence has not been published in a source we could verify.

At a glance

Type: Peptide
Size: 10 amino acids (decapeptide), 5 of them changed from natural GnRH
Sequence: [Ac-D-Nal][D-Cpa][D-Pal]SY[D-Cit]LRP[D-Ala]-NH2
Formula: C70H92ClN17O14
Molecular weight: 1431.06 (anhydrous free base, FDA label)
CAS number: 120287-85-6
Origin: Synthetic analog of the natural brain hormone GnRH, with substitutions at positions 1, 2, 3, 6 and 10 (several unnatural D-amino acids).
Evidence: FDA-approved
US FDA status: FDA-approved as Cetrotide (EMD Serono, NDA 021197, August 11, 2000) to inhibit premature LH surges in women undergoing controlled ovarian stimulation. The 0.25 mg vial is a current prescription product; the 3 mg vial is listed as discontinued ¹². Generic cetrorelix 0.25 mg is approved from Livzon, Qilu, Gland, Xiromed and Epic Pharma; the first generic (Teva, 2022) is listed as discontinued ³.

Overview

How it works

Established: cetrorelix competes with natural GnRH for its receptor on cells in the pituitary gland, so the pituitary releases less LH and FSH. The effect is stronger on LH than on FSH and is dose-dependent ¹. Unlike GnRH agonists such as leuprolide, it does not cause an initial burst of hormone release; LH suppression starts within about 1 to 2 hours and wears off after treatment stops ¹. In IVF this prevents the mid-cycle LH surge that would otherwise cause eggs to be released before retrieval ¹.

What research shows

FDA label program (human trials, 732 women treated in 2 Phase 2 and 3 Phase 3 trials): a premature LH surge occurred in 0% (3 mg single dose, n=115), 1.9% (0.25 mg daily, n=159) and 1.0% (0.25 mg daily, n=303) of women; clinical pregnancy rates were about 20–23% per attempt ¹.
Head-to-head RCT vs ganirelix (CAP IV, open-label, n=185, 16 US clinics): no premature LH surge in either group and no significant difference in pregnancy or other IVF outcomes; cetrorelix (single 3 mg dose) needed fewer injections ⁵.
Cochrane review (73 RCTs, n=12,212) of GnRH antagonists as a class vs long agonist protocols: no clear difference in live birth (OR 1.02), but less ovarian hyperstimulation syndrome with antagonists (OR 0.61); evidence quality moderate ⁴.
RCT in stimulated intrauterine insemination cycles: cetrorelix lowered premature luteinization but did not change pregnancy or cancellation rates ¹¹.

Doses studied in people

Study or label	Dose used	Source
FDA label (inhibition of premature LH surge during controlled ovarian stimulation)	0.25 mg once daily, subcutaneous, started on stimulation day 5 or 6 and continued until the day of hCG	¹
FDA label Phase 3 single-dose regimen (n=115; 3 mg strength now discontinued in the US)	3 mg once, subcutaneous, with 0.25 mg daily added if hCG was not given within 4 days	¹
Open-label RCT vs ganirelix (n=185)	3 mg once, subcutaneous, switched to 0.25 mg daily if hCG criteria were not met after 4 days	⁵

Doses shown are from the FDA label and published trials only; they are reported, not recommended. Cetrorelix is used only under a fertility specialist's care.

Read this first: these are the amounts given to participants in published studies or written on official prescribing labels, reported for reference. They are not recommendations. Trial doses were chosen for specific patients under medical supervision, and a dose that is safe in one person can be harmful in another.

Safety

Label adverse events (n=949 in clinical studies): ovarian hyperstimulation syndrome 3.5%, nausea 1.3%, headache 1.1% ¹.
Injection-site reactions (redness, bruising, itching, swelling) were reported and were usually mild and short-lived ¹.
Allergic reactions, including anaphylactoid reactions with the first dose, have been reported after marketing; one severe anaphylactic reaction occurred after 7 months of 10 mg/day in a non-fertility study ¹.
Liver enzymes rose (up to 3 times normal) in 1–2% of women; clinical meaning unknown ¹.
Contraindicated in known or suspected pregnancy, breastfeeding, severe kidney impairment, and allergy to cetrorelix, mannitol or GnRH analogs. In animals it caused loss of pregnancy (fetal resorption) ¹.
Follow-up of 316 newborns found some major and minor birth defects; the label states the causal link to cetrorelix is unknown because IVF, ICSI and other drugs are confounders ¹.
No long-term animal cancer studies have been done ¹.

Report side effects of any drug or product to the FDA through MedWatch. For a possible poisoning in the US, call Poison Control at 1-800-222-1222.

Legal status

FDA: FDA-approved as Cetrotide (EMD Serono, NDA 021197, August 11, 2000) to inhibit premature LH surges in women undergoing controlled ovarian stimulation. The 0.25 mg vial is a current prescription product; the 3 mg vial is listed as discontinued ¹². Generic cetrorelix 0.25 mg is approved from Livzon, Qilu, Gland, Xiromed and Epic Pharma; the first generic (Teva, 2022) is listed as discontinued ³.
Compounding: Not named in FDA's 503A nominated bulk substances category list (updated May 14, 2026) ¹⁰. FDA-approved brand and generic products exist.
Sports (WADA): Not named on the WADA 2026 Prohibited List. Section S2.2.1 bans GnRH and its agonist analogues (e.g. leuprorelin) in males; antagonists such as cetrorelix are not listed ⁸.
Other: Prescription-only (Rx only) ¹. Authorized in the EU as Cetrotide since April 1999 (holder now Merck Europe B.V.) ⁷.

Rules change often. See Legal status of peptides for how these categories work.

Storage and stability

Label: store the 0.25 mg kit refrigerated at 2–8°C (36–46°F) in its carton to protect from light ¹.

General lab handling, not instructions for personal use. See Storage and stability.

History

Cetrorelix was discovered by Andrew Schally in 1988 and was originally used to treat prostate cancer and benign prostate enlargement ⁶. In 1999 it became the first "third-generation" GnRH antagonist on the EU market for IVF ⁶; the European Commission authorized Cetrotide in April 1999 ⁷. The FDA approved Cetrotide (EMD Serono) on August 11, 2000 ². The 3 mg single-dose vial is now listed as discontinued in the US, while the 0.25 mg vial remains a prescription product ²³. Several companies have FDA-approved generic cetrorelix 0.25 mg; the first (Teva, approved August 2022) is now listed as discontinued, and others followed from 2024 onward ³.

Common questions

Is cetrorelix FDA-approved?

Yes. Cetrotide was approved in August 2000 to stop early LH surges during IVF-type ovarian stimulation, and generic versions have been approved since 2022 ¹²³.

Is Cetrotide still sold in the US?

The 0.25 mg vial is listed as an active prescription product, but the 3 mg single-dose vial is listed as discontinued ². Generic 0.25 mg cetrorelix from several makers is also listed ³.

How is it different from ganirelix or leuprolide?

Cetrorelix and ganirelix are both GnRH blockers (antagonists) and worked similarly in a 185-woman head-to-head trial ⁵. Agonists like leuprolide first stimulate the pituitary before shutting it down, while cetrorelix blocks it right away ¹.

What are the main risks?

In label studies, ovarian hyperstimulation syndrome (3.5%), nausea and headache were most common, plus mild injection-site reactions ¹. Rare allergic reactions have been reported, and it must not be used in pregnancy ¹.

Is cetrorelix banned in sport?

It is not named on the WADA 2026 Prohibited List, which bans GnRH and its agonist analogues in male athletes but does not list antagonists ⁸.

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Ganirelix

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Ganirelix is a lab-made peptide that briefly blocks the brain signal that triggers ovulation.

Sources

Curious how a compound like this one becomes an approved medicine? The Academy track How a peptide becomes a medicine walks through it. You can try the Academy free first.

Last reviewed 2026-10-30 · How we research · Found an error? See our corrections policy.