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Cetrorelix

Also known as: Cetrotide, cetrorelix acetate, SB-75, LHRH antagonist (synthetic decapeptide)

GnRH receptor antagonist — synthetic decapeptide; gonadotropin suppressant

Research chemicalLast updated: October 10, 2026Based on 8 peer-reviewed studiesPreclinical data only — no human trials
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What it is

Cetrotide (cetrorelix) is an injection used during IVF fertility treatment to stop eggs from being released too early. It blocks a hormonal signal in the brain, giving doctors precise control over the timing of ovulation during stimulated cycles. FDA-approved since 1999.

The scientific side

cetrorelix is a synthetic decapeptide that acts as a competitive antagonist at pituitary gonadotropin-releasing hormone (GnRH) receptors — also termed LHRH (luteinizing hormone-releasing hormone) receptors. By occupying GnRH receptors without activating them, cetrorelix produces immediate, dose-dependent inhibition of both LH and FSH secretion from the anterior pituitary gland. This competitive blockade is the critical mechanistic distinction from GnRH agonists such as buserelin or leuprolide, which paradoxically cause an initial stimulatory 'flare' before receptor downregulation; cetrorelix produces no such flare, allowing rapid and reversible gonadotropin suppression from the first dose. In controlled ovarian stimulation for IVF, daily subcutaneous administration of cetrorelix during the late follicular phase prevents the premature LH surge that would otherwise trigger ovulation before oocyte retrieval is scheduled. Clinical trials show this translates to comparable oocyte yields and live birth rates versus GnRH agonist protocols but with a significantly shorter duration of gonadotropin stimulation and lower total gonadotropin dose requirement. The 3 mg single-dose protocol exploits the pharmacokinetic durability of cetrorelix — serum concentrations in IVF patients have been measured in the range of 0.29 to 5.12 ng/mL with sustained suppression for approximately 96 hours — though no correlation between serum concentration and pregnancy outcome was observed within this range. Beyond reproductive endocrinology, GnRH receptors are expressed in peripheral tissues including the prostate, ovary, and certain cancer cell types. In epithelial ovarian cancer cell lines and xenograft models, cetrorelix has been shown to induce apoptosis via suppression of the PI3K/AKT pathway and downstream upregulation of the pro-apoptotic transcription factor FOXO1, through a mechanism that requires GnRH receptor expression on tumor cells. In prostate stromal and epithelial cells, cetrorelix similarly inhibited proliferation and increased p53 expression in vitro, supporting potential therapeutic roles in benign prostatic hyperplasia. Animal studies further demonstrate that cetrorelix suppresses dominant follicle regression and synchronizes follicular wave emergence, confirming its reliable GnRH receptor-mediated effects across mammalian species.

Class: GnRH receptor antagonist — synthetic decapeptide; gonadotropin suppressant

Administration & storage

Administration
Subcutaneous injection into the lower abdominal wallpreferably below the navelInjection site should be varied with each administration to reduce local reactionsAdministered using the needle provided in the co-packaged prefilled syringePatient self-injection is standard practice during IVF monitoring cycles after initial training
Storage
Store Cetrotide vials at room temperature, 25°C (77°F); excursions permitted to 15–30°C. Protect from light. Do not freeze. Reconstituted solution must be used immediately and not stored.
Cautions
Cetrorelix is contraindicated in women with known hypersensitivity to cetrorelix, mannitol, or any GnRH or GnRH analogue. Allergic reactions including anaphylaxis have been reported.,Cetrorelix is contraindicated in pregnancy and during breastfeeding; it causes fetal harm based on mechanism.,Ovarian hyperstimulation syndrome (OHSS) can occur with any COS protocol including cetrorelix-based regimens; incidence appears lower with cetrorelix versus GnRH agonist long protocols based on comparative trial data.,Injection site reactions (redness, swelling, itching) are common; most are mild and transient at the 0.25 mg dose.,Hepatic impairment: cetrorelix is primarily eliminated hepatically; use with caution in patients with significant liver disease.,Renal impairment: limited pharmacokinetic data in renal impairment; use with caution in moderate-to-severe renal disease.

Legal & regulatory status

US FDA

FDA-approved (NDA 021197) as Cetrotide (cetrorelix for injection) for the inhibition of premature LH surges in women undergoing controlled ovarian stimulation. Approved August 1999. Two clinical dosing protocols are…

WADA

Cetrorelix is prohibited under the WADA Prohibited List. GnRH antagonists, including cetrorelix, fall under Section S2 (Peptide Hormones, Growth Factors, Related Substances and Mimetics) and are prohibited both…

Health Canada

Cetrorelix acetate is authorized for sale in Canada as Cetrotide for the inhibition of premature LH surges in women undergoing controlled ovarian hyperstimulation in conjunction with gonadotropins. The indication and…