RESEARCH MONOGRAPH · KDC-MN-285

Cetrorelix

May 9, 2026 Kodiac biolabs Research Revised May 30, 2026 3 min read

Our opinion on this compound

78/100

The cleaner way to suppress gonadotropins when you dont want the flare phase, underrated outside reproductive endocrinology

Cetrorelix is the third-generation GnRH antagonist that ASTA Medica and Serono developed in the 90s, and honestly it's underrated outside the IVF crowd that uses it routinely. The whole point of the antagonist class versus the agonists is that you skip the flare phase entirely. Receptor occupancy is competitive, suppression starts within hours, and recovery on washout is comparably rapid. For a lot of research models that's the more useful tool.

Mechanism is well-mapped. Cetrorelix is a decapeptide with multiple D-amino acid substitutions and N-acetylation at the N-terminus that together kill receptor activation while preserving binding. The result is straight GnRH receptor blockade without the partial agonism that some earlier antagonists in the class had.

The clinical evidence is strongest in assisted reproduction, where cetrorelix prevents the premature LH surge during controlled ovarian stimulation. The phase 3 work that got Cetrotide approved in the late 90s is solid, and the comparative efficacy versus the long agonist protocols is well-established. There's also a smaller body of work in benign prostatic hyperplasia and endometriosis, and a tail of research on its histamine-releasing potential at higher doses (a class issue with second/third-generation antagonists that mostly got solved in the move to degarelix and the orals).

What we like: clean pharmacology, fast on-fast off, and the IVF reference data is excellent. Cetrorelix acetate as research material is well-characterized.

What we dont love is that cetrorelix has been somewhat eclipsed clinically by degarelix in oncology and by the oral GnRH antagonists (relugolix, elagolix) in chronic-use indications. The pharma volume has dropped, which puts mild pressure on sourcing.

For research, the appeal is the cleanness. If you want to suppress gonadotropins without dealing with the agonist flare confounding your early timepoints, cetrorelix is the right tool. Half-life sits in a useful range (around 60 hours after subcutaneous dosing) and the dose-response is well-mapped.

Sourcing is decent. Pharma-grade cetrorelix acetate exists, research-grade material from peptide suppliers typically lands above 95 percent, and the failure modes (incomplete N-acetylation, racemization at the D-residues) are well-understood QC items. We rate it solidly underrated for a research peptide thats this well-characterized.

Evidence: 85
Mechanism: 90
Reliability: 85
Safety: 75
Sourcing: 75
Value: 70
Signal: 70
Staying power: 75

Plain-language summary Intrigue 55 / 100

Cetrorelix (Cetrotide) is a GnRH receptor blocker (rather than an agonist), approved in 2000 and used in IVF protocols to prevent the premature LH surge that would otherwise disrupt egg retrieval timing. Unlike GnRH agonists, which cause an initial flare followed by suppression, cetrorelix produces immediate dose-dependent suppression of LH and FSH with no flare. That allows brief, on-demand control of the reproductive axis without the one-to-two-week desensitization delay required of agonists. Standard IVF use is a daily 0.25 mg injection from stimulation day 5 until the trigger shot. Generally well tolerated with minor injection-site reactions. Not stocked by Kodiac. This monograph is provided for research and educational reference.

Intrigue 0–100 blends mechanism novelty, evidence strength, and translational potential. Kodiac editorial, not peer-reviewed.

Synthetic GnRH antagonist

A synthetic GnRH receptor antagonist used in IVF protocols to prevent premature LH surge; immediate suppression without the agonist flare.

Abstract

Cetrorelix (Ac-D-2-Nal-D-Cpa-D-Pal-Ser-Tyr-D-Cit-Leu-Arg-Pro-D-Ala-NH2; CAS 120287-85-6; molecular formula C70H92ClN17O14; molecular weight 1431.06) is a synthetic GnRH receptor antagonist decapeptide developed at ASTA Medica and approved by the FDA in 2000 under the trade name Cetrotide. Mechanism: competitive antagonism at pituitary GnRH receptors, producing immediate dose-dependent suppression of LH and FSH without the initial flare characteristic of GnRH agonists. The antagonist mechanism allows brief, on-demand HPG suppression without the 7-to-10-day desensitization period required for GnRH agonist effect. Plasma half-life is approximately 60 hours after subcutaneous dosing. Approved for prevention of premature LH surge in controlled ovarian stimulation for IVF; the dose protocol begins on stimulation day 5 and continues through hCG trigger. Off-label use in benign prostatic hyperplasia and prostate cancer (where the avoidance of testosterone flare is clinically valuable). Used as the canonical GnRH antagonist in IVF research.

Mechanism of action

Competitive GnRH receptor antagonism; immediate dose-dependent suppression of LH and FSH without the agonist flare.

Reported research dose ranges

Clinical IVF 0.25 mg subcutaneous from stimulation day 5 through hCG trigger; alternative single 3 mg dose on stimulation day 7.

References

Felberbaum RE, et al. Cetrorelix in IVF: a meta-analysis. Hum Reprod Update 2002.
Reissmann T, et al. The LHRH antagonist cetrorelix: a review. Hum Reprod Update 2000.
Olivennes F, et al. Use of GnRH antagonists in reproductive medicine. Hum Reprod Update 2002.

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KDC-MN-285

The full reference document is provided strictly for research use only. It reports research dose ranges from the published literature, not instructions for use in humans or animals.

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FOR RESEARCH USE ONLY. Not for medical, diagnostic, or therapeutic purposes. Not for human consumption. All information is provided for research and educational purposes only.

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Cetrorelix

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Mechanism of action

Reported research dose ranges

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Abstract

Mechanism of action

Reported research dose ranges

References

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