Page data last changed: . Chemistry registry snapshot: . Registry refreshes and identity assessments are separate from scientific content review.
Blocks GnRH receptors directly — no initial hormone flare, unlike agonists.
Also known as: Cetrotide · GnRH antagonist
Part of the Foundational & therapeutic peptides cluster
Overview
Cetrorelix is a synthetic decapeptide GnRH antagonist that competitively blocks the GnRH receptor. It is an approved prescription medicine used in in-vitro fertilization to prevent premature luteinizing hormone surges. This page is educational and is not medical advice.
Source & context
Biological / chemical source: Synthetic decapeptide analog of GnRH
Primary research or clinical context: Approved medicine used in assisted reproduction to prevent premature luteinizing hormone surges (prescription)
Antagonist vs. agonist
Unlike GnRH agonists, which cause an initial hormone surge before suppression, antagonists like cetrorelix block the receptor immediately. This rapid, flare-free suppression is valued in fertility protocols where precise timing of the LH surge matters.
Design
Cetrorelix incorporates multiple non-natural amino-acid substitutions across the GnRH decapeptide backbone. These changes convert the natural agonist into a stable competitive antagonist while resisting enzymatic degradation.
Sequence
One-letter sequence commonly cited for Cetrorelix (educational; isoforms and modifications may differ):
AFASYXLRPA
X = non-canonical residue (Residue 6 is N<sup>5</sup>-D-aminocarbonylornithine (D-Cit); N-terminal alanine is N-acetylated,2-naphthalenyl-alanine (Ac-D-Nal) ; C-terminal D-alanine is amidated; residue 2 is D-chlorophenyalanine (D-Cpa); residue 3 is 3-pyridinyl-D-alanine (D-Pal)). X marks a non-canonical residue — see the structure block below. (Plotted as alanine on the wheel.)
Residues plotted ~100° apart around an α-helix — clustering of one color reveals an amphipathic face.
Structure & chemistry
Molecular identity & reference confidence
Source-supported reference
Reference values are taken from the cited molecular record or curated profile. A database match is not independent laboratory verification; modifications, counter-ions, and formulations can change the measured mass.
- Molecular form
- Cetrorelix (source record; form not independently established)
- Species
- Not established by this molecular identity audit
- Termini (N / C)
- Not specified / Not specified
Average reference mass
Reference policy updated: 2026-10-05
- IUPHAR/BPS source snapshot · 2026-10-01
- PubChem molecular record · 2026-10-01
- Molecular formula
- C70H92ClN17O14
- Average reference mass
- ≈ 1,431
- Status
- Approved medicine in at least one jurisdiction (IUPHAR record)
Residue 6 is N<sup>5</sup>-D-aminocarbonylornithine (D-Cit); N-terminal alanine is N-acetylated,2-naphthalenyl-alanine (Ac-D-Nal) ; C-terminal D-alanine is amidated; residue 2 is D-chlorophenyalanine (D-Cpa); residue 3 is 3-pyridinyl-D-alanine (D-Pal)
- PubChem CID: 25074887
- IUPHAR ligand: 1190
- ChEMBL: CHEMBL1200490
- DrugBank: DB00050
- CAS RN: 120287-85-6
- UNII: OON1HFZ4BA
Chemistry values: IUPHAR/BPS Guide to Pharmacology, PubChem · fetched 2026-10-01.
Clinical development snapshot
ClinicalTrials.gov lists 140 registered studies with “Cetrorelix” as an intervention (snapshot 2026-10-01). A registry footprint is not evidence of efficacy or approval.
| NCT | Title | Phase | Status | Updated |
|---|---|---|---|---|
| NCT07732348 | Oral GnRH Antagonist (Linzagolix) Versus Injectable GnRH Antagonist in Controlled Ovarian Stimulation for In V | Not applicable | not yet recruiting | 2026-09-30 |
| NCT07836400 | Half-dose vs Conventional-dose Cetrorelix in ICSI Cycles | — | not yet recruiting | 2026-09-23 |
| NCT07340827 | A Study to Compare the Efficacy and Safety of Follitropin Alfa/Lutropin Alfa Versus hMG in Japanese Participan | Phase 3 | recruiting | 2026-09-08 |
| NCT07736261 | Drospirenone-Primed Ovarian Stimulation Versus GnRH Antagonist Protocol in Poor Ovarian Responders Undergoing | Phase 2 | not yet recruiting | 2026-07-30 |
| NCT06572930 | Serum FSH Monitoring for Identification of an Optimal Range During Ovarian Stimulation | — | recruiting | 2026-06-25 |
| NCT06212102 | Dydrogesterone Versus GnRH Antagonist in Poor Responders Undergoing Double Ovarian Stimulation | Phase 2 | recruiting | 2026-05-04 |
Cetrorelix — reconstitution calculator
Enter how much peptide is in the vial and how much diluent (e.g. bacteriostatic water) is added. The tool returns the resulting solution concentration — and, for any amount you type, the volume it corresponds to. This is educational arithmetic, not a dosing recommendation.
Reference form: Cetrorelix (source record; form not independently established)Average reference mass: 1,431 Da
Enter an amount to see the volume it corresponds to.
Educational concentration mathematics only. This tool does not recommend a dose, amount, or protocol, and nothing here is medical advice. Many peptides are not authorized by Health Canada for human use — see our reconstitution and bacteriostatic-water guides for context.
Change log
Dated observations from the data pipeline (registry flags, trial footprints, identifiers) and editorial reviews of this profile.
- Trials1 registered study added on ClinicalTrials.gov (now 140).
FAQ about Cetrorelix
What is Cetrorelix?+
Cetrorelix is a synthetic decapeptide GnRH antagonist that competitively blocks the GnRH receptor. It is an approved prescription medicine used in in-vitro fertilization to prevent premature luteinizing hormone surges. This page is educational and is not medical advice.
What Canadian product status is recorded for Cetrorelix?+
Canadian product status for Cetrorelix has not been verified in this profile. No verified record here does not mean no authorization exists. Status depends on the product, formulation and use; consult Health Canada's product records.
What is the typical length of Cetrorelix?+
Cetrorelix is commonly described as approximately 10 amino acids (GnRH antagonist (decapeptide analog)).
Related peptides
References & further reading
- 1.Tur-Kaspa et al. (2009). GnRH antagonist, cetrorelix, for pituitary suppression in modern, patient-friendly assisted reproductive technology. Expert Opin Drug Metab Toxicol
- 2.Hebisha et al. (2017). GnRH Antagonist Cetrorelix Administration Before hCG for Protection of Ovarian Hyperstimulation Syndrome. J Obstet Gynaecol India
- 3.Ludwig et al. (2002). Tailoring the GnRH antagonist cetrorelix acetate to individual patients' needs in ovarian stimulation for IVF: results of a prospective, randomized study. Hum Reprod
- 4.Findeklee et al. (2023). Cetrorelix in reproductive medicine. F S Rep
- 5.Zhao et al. (2010). GnRH antagonist cetrorelix inhibits mitochondria-dependent apoptosis triggered by chemotherapy in granulosa cells of rats. Gynecol Oncol
- 6.Reissmann et al. (2000). The LHRH antagonist cetrorelix: a review. Hum Reprod Update
- 7.Zhang et al. (2025). Cetrorelix promotes cell apoptosis via the PI3K-AKT-FOXO1 pathway in epithelial ovarian cancer. Front Oncol
- 8.Ludwig et al. (2000). Significant reduction of the incidence of ovarian hyperstimulation syndrome (OHSS) by using the LHRH antagonist Cetrorelix (Cetrotide) in controlled ovarian stimulation for assisted reproduction. Arch Gynecol Obstet
- 9.PubChem — compound summary for Cetrorelix (CID 16130924)
- 10.Wikipedia — Cetrorelix