What is Cetrorelix?
Cetrorelix is a synthetic decapeptide that acts as a competitive antagonist at gonadotropin-releasing hormone (GnRH) receptors on pituitary cells. Unlike GnRH agonists, which cause an initial hormonal surge before suppression, cetrorelix produces immediate, dose-dependent suppression of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) without any initial flare effect. This makes it particularly valuable in reproductive medicine, where preventing a premature LH surge during controlled ovarian stimulation is critical to assisted reproduction outcomes.
The peptide was developed as a third-generation GnRH antagonist, synthetically modified to overcome the histamine-releasing properties associated with earlier GnRH antagonists. Its competitive binding to pituitary GnRH receptors is fully reversible, and normal gonadotropin secretion resumes promptly once the drug clears the system. This reversibility is a meaningful clinical advantage over GnRH agonist protocols, which can suppress pituitary function for weeks after discontinuation.
Clinically, cetrorelix has been studied in large multicenter Phase IIIb trials evaluating both multiple-dose (0.25 mg/day) and single-dose (3 mg) protocols in the context of in vitro fertilization. Both approaches achieved suppression of premature LH surges in over 90% of patients and produced comparable pregnancy and live birth rates to long GnRH agonist protocols, while requiring shorter durations of gonadotropin stimulation and lower total gonadotropin doses. The incidence of ovarian hyperstimulation syndrome (OHSS) was also reduced compared to agonist-based protocols.
Beyond reproductive medicine, cetrorelix has been investigated in hormone-sensitive conditions including prostate cancer, breast cancer in pre- and perimenopausal women, endometriosis, uterine fibroids, and endometrial thinning. These applications exploit the peptide's ability to suppress circulating sex hormones rapidly. While FDA approval is specifically for use in ART (assisted reproductive technology), ongoing research continues to explore expanded indications in hormone-dependent disease states.
Research Supply
Source high-purity Cetrorelix for your research
Dosage Guide
Route: Subcutaneous injection
Dosing Schedule
| Period | Dose |
|---|---|
| Multiple-dose protocol | 0.25 mg once daily (approximately 24-hour suppression per dose) |
| Single-dose protocol | 3 mg one injection (depot effect; up to 96-hour suppression) |
Reconstitution
Injection Volumes
| Dose | Volume | Syringe Units |
|---|---|---|
| 0.25 mg | 1 mL | Full 0.25 mg vial |
| 3 mg | 3 mL | Full 3 mg vial; depot release over up to 96 hours |
Administration Tips
- Reconstitute with the sterile water provided in the kit
- Use immediately after reconstitution
- In ART protocols, either approach is typically combined with gonadotropin stimulation (FSH or hMG)
- Terminate cetrorelix with HCG trigger administration for oocyte maturation
- The single 3 mg dose forms a subcutaneous depot providing sustained LH suppression for up to four days
- The multiple-dose 0.25 mg protocol begins on stimulation day 5 or 6 and continues through HCG administration
Risks & Side Effects
Commonly Reported
Serious Risks
Severe OHSS
Rare but serious: abdominal pain, bloating, difficulty breathing, and reduced urination. Requires prompt medical evaluation.
Hypersensitivity reactions
Rash and urticaria have been reported. Anaphylaxis is rare but documented in the GnRH antagonist class.
Fetal harm
Cetrorelix is contraindicated during pregnancy. It must not be used once pregnancy is confirmed.
Contraindications
- Pregnancy or breastfeeding
- Hypersensitivity to cetrorelix, mannitol, GnRH, or other GnRH analogs
- Severe renal impairment
- Postmenopausal status (in the reproductive indication)
- Pediatric patients
Frequently Asked Questions
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Experts Covering Cetrorelix
LEGAL DISCLAIMER
The information provided on this page is for educational and informational purposes only and is not intended as medical advice. Cetrorelix has not been approved by the FDA for any medical condition beyond controlled ovarian stimulation in ART. Always consult with a qualified healthcare professional before starting any peptide therapy. Individual results may vary. Peptides Institute is not responsible for any adverse effects resulting from the use of information provided on this site.