Hormonal & Sexual Health

Cetrorelix

Cetrorelix switches off the pituitary's signal to the ovaries within hours of an injection, and does it by blocking the receptor rather than exhausting it, so there is none of the hormone surge that older agonist drugs cause before they finally shut the system down. In IVF (in vitro fertilisation) that buys control: the egg cannot be released early and waste a stimulated cycle. It has been FDA-approved as Cetrotide since 2000, and a Cochrane pooling of 73 randomised trials in 12,212 women, 44 of them using cetrorelix, found live birth rates matching the older protocol with clearly less ovarian hyperstimulation syndrome. It does not treat infertility; it protects one step inside a cycle.

Last updated 12 August 2026

Studied forPremature LH surge prevention · Ovarian stimulation control · Fertility protocol research

Evidence on fileFDA-approved · 1 randomised human trial · 1 human observational study

Strongest sourceOvarian stimulation with HMG: results of a prospective randomized phase III European study comparing the lute… (randomised human trial)

Mechanism

Competes with GnRH at pituitary receptors, suppressing LH and FSH release without the initial flare seen with agonists.

Regulatory status

Approved by the FDA. Marketed as CETROTIDE, CETRORELIX ACETATE. Earliest approval 2000-08-11. Application NDA021197, ANDA214540, ANDA217776, ANDA218150.

An approval grades as rung 1 on this site, because 21 CFR 314.126 requires adequate and well-controlled human investigations and one cannot be granted without them. It covers specific indications and doses, though, and does not transfer to other uses of the same molecule.

Reported effects

What sources associate with this compound. Reported categories, not outcomes we have graded — each would need its own citation and rung.

Premature LH surge prevention
Ovarian stimulation control
Fertility protocol research

Dosing on file unverified

0.25 mg SC QD starting day 5-6 of stimulation until hCG day; 3 mg single dose also available

Carried from a source that labels it unverified, and reproduced with that label attached. A record of what is reported, not a recommendation. No citation on this page establishes it.

Half-life, storage & sport

Elimination half-life: 5 to 10 hr (human, SC) — study. Biology of reproduction 2026; women, after a single subcutaneous treatment.

The half-life on file is 7.5 h, measured subcutaneously. On the schedule this record states — daily — each dose has fallen to 11% of its own peak by the time the next is given. Nothing accumulates, and there is no loading phase to run.

Dosed daily over 4 d, each dose normalised to the first peak.

The rise is not modelled and the axis is not a blood level. No absorption rate constant and no volume of distribution are on file, so each dose appears at full height the instant it is given, and the axis is percent of this compound's own peak.

Literature on file 3

human RCT
Ovarian stimulation with HMG: results of a prospective randomized phase III European study comparing the luteinizing hormone-releasing hormone (LHRH)-antagonist cetrorelix and the LHRH-agonist buserelin (Human Reproduction 2000, cited 252x) graded on: a randomised study — “randomized phase III European study”
human observational
Suppression of the endogenous luteinizing hormone surge by the gonadotrophin-releasing hormone antagonist Cetrorelix during ovarian stimulation (Human Reproduction 1994, cited 239x) graded on: indexed as a clinical trial, design not stated — “Clinical Trial”
human RCT
FDA approval NDA021197, ANDA214540, ANDA217776, ANDA218150 graded on: an FDA approval (NDA021197, ANDA214540, ANDA217776, ANDA218150), which requires adequate and well-controlled human investigations — “NDA021197, ANDA214540, ANDA217776, ANDA218150”

Identity

Space-filling 3D model of Cetrorelix, carbon grey, nitrogen blue, oxygen red — Built from the SMILES on this record — the atoms and bonds are exact. The shape is **one computed low-energy pose**, not a measured structure: a flexible peptide in solution has no single conformation, and where the SMILES leaves a stereocentre undefined the pose commits to one arbitrarily. The skeletal formula below claims connectivity and nothing more, which is what we actually know.

2D chemical structure of Cetrorelix — Built from the SMILES on this record — the atoms and bonds are exact. The shape is **one computed low-energy pose**, not a measured structure: a flexible peptide in solution has no single conformation, and where the SMILES leaves a stereocentre undefined the pose commits to one arbitrarily. The skeletal formula below claims connectivity and nothing more, which is what we actually know.

Molecular weight: 1431.0
Molecular formula: C70H92ClN17O14
CAS number: 120287-85-6
PubChem CID: 25074887
InChI key: SBNPWPIBESPSIF-MHWMIDJBSA-N
Sequence: XXXSYXLRPA
SMILES: C[C@H](C(=O)N)NC(=O)[C@@H]1CCCN1C(=O)[C@H](CCCN=C(N)N)NC(=O)[C@H](CC(C)C)NC(=O)[C@@H](CCCNC(=O)N)NC(=O)[C@H](CC2=CC=C(C=C2)O)NC(=O)[C@H](CO)NC(=O)[C@@H](CC3=CN=CC=C3)NC(=O)[C@@H](CC4=CC=C(C=C4)Cl)NC(=O)[C@@H](CC5=CC6=CC=CC=C6C=C5)NC(=O)C
InChI: InChI=1S/C70H92ClN17O14/c1-39(2)31-52(61(94)82-51(15-9-28-77-69(73)74)68(101)88-30-10-16-58(88)67(100)79-40(3)59(72)92)83-60(93)50(14-8-29-78-70(75)102)81-63(96)54(34-43-20-25-49(91)26-21-43)86-66(99)57(38-89)87-65(98)56(36-45-11-7-27-76-37-45)85-64(97)55(33-42-18-23-48(71)24-19-42)84-62(95)53(80-41(4)90)35-44-17-22-46-12-5-6-13-47(46)32-44/h5-7,11-13,17-27,32,37,39-40,50-58,89,91H,8-10,14-16,28-31,33-36,38H2,1-4H3,(H2,72,92)(H,79,100)(H,80,90)(H,81,96)(H,82,94)(H,83,93)(H,84,95)(H,85,97)(H,86,99)(H,87,98)(H4,73,74,77)(H3,75,78,102)/t40-,50-,51+,52+,53-,54+,55-,56-,57+,58+/m1/s1

Notes unverified prose

FDA-approved (Cetrotide); DailyMed; Drugs.com

Not on file 0

All 8 tracked fields hold a value on this record: molecular weight and formula, CAS number, PubChem CID, amino-acid sequence, SMILES, InChI and InChI key.

Counted from the record itself, not from what a source said it was missing. 163 of 188 records still have at least one empty.

Listed prices 1

What 1 shop we track listed for Cetrorelix, read from their own public catalogues on 2026-09-14. We take no commission on these and they are not ranked by any payment — how vendors are scored.

Compare prices1 listing from 1 shop

Listed in CAD
Vendor	Size	Price	Per mg
Peptide Shop Canada	5 mg	$134.00 CAD	$26.80/mg

Prices are the vendor's own listing, reproduced with the date we read it — never converted between currencies, and compared per milligram only where the vendor states the vial size.

At a glance

Strongest rung: human RCT
Citations: 3
Regulatory: FDA approved
Route: Subcutaneous
Declared gaps: 0

Citations by rung

Strongest wins, never an average.