Cetrorelix and degarelix are both FDA-approved GnRH antagonists — they block the GnRH receptor directly, suppressing sex hormones immediately with no flare (unlike GnRH agonists). The difference is mainly the clinical setting: cetrorelix is used in fertility treatment, degarelix in advanced prostate cancer.
At a glance
| Cetrorelix | Degarelix | |
|---|---|---|
| Class | GnRH antagonist | GnRH antagonist |
| Brand name | Cetrotide | Firmagon |
| FDA status | Approved | Approved |
| Primary use | Preventing premature ovulation in IVF | Advanced prostate cancer |
| Onset | Immediate suppression, no flare | Immediate suppression, no flare |
| Dosing | Short-term during IVF cycles | Monthly depot injection |
The bottom line
Bottom line: Same mechanism (immediate hormone suppression without a flare), different jobs. Cetrorelix is used short-term in IVF to prevent premature ovulation; degarelix is a monthly depot for prostate cancer where avoiding the agonist "flare" is an advantage. Both are approved prescription medicines.
Frequently asked questions
What's the difference between cetrorelix and degarelix?
Both are FDA-approved GnRH antagonists that suppress sex hormones immediately without a flare. Cetrorelix (Cetrotide) is used in IVF to prevent premature ovulation, while degarelix (Firmagon) is a monthly depot for advanced prostate cancer.
Why use an antagonist instead of an agonist?
GnRH antagonists suppress hormones immediately with no initial flare, which is advantageous in settings like prostate cancer where a temporary testosterone surge is undesirable, and in IVF for precise cycle control.
Are both FDA-approved?
Yes. Cetrorelix and degarelix are both FDA-approved GnRH antagonists for their respective indications, used under medical supervision.
References
Combined peer-reviewed sources from both peptide guides. Inclusion is not endorsement.
- Lee TH, Lin YH, Seow KM, et al. Effectiveness of cetrorelix for prevention of premature LH surge during controlled ovarian stimulation: a randomized trial. Fertil Steril. 2008. Peer-reviewed study
- Lin YH, Seow KM, Chen HJ, et al. Effect of cetrorelix dose on premature LH surge during ovarian stimulation. Reprod Biomed Online. 2008. Peer-reviewed study
- Finas D, Hornung D, Diedrich K, et al. Cetrorelix in the treatment of female infertility and endometriosis. Expert Opin Pharmacother. 2006. Peer-reviewed study
- Tur-Kaspa I, Ezcurra D. GnRH antagonist, cetrorelix, for pituitary suppression in modern, patient-friendly assisted reproductive technology. Expert Opin Drug Metab Toxicol. 2009. Peer-reviewed study
- Reissmann T, Schally AV, Bouchard P, et al. The LHRH antagonist cetrorelix: a review. Hum Reprod Update. 2000. Peer-reviewed study
- Kanda A, Nobukiyo A, Sotomaru Y. Effect of Cetrorelix administration on ovarian stimulation in aged mice. Exp Anim. 2021. Peer-reviewed study
- Zengerling F, Jakob JJ, Schmidt S, et al. Degarelix for treating advanced hormone-sensitive prostate cancer. Cochrane Database Syst Rev. 2021. Peer-reviewed study
- Devos G, Tosco L, Baldewijns M, et al. ARNEO: A Randomized Phase II Trial of Neoadjuvant Degarelix with or Without Apalutamide Prior to Radical Prostatectomy for High-risk Prostate Cancer. Eur Urol. 2023. Peer-reviewed study
- Lopes RD, Higano CS, Slovin SF, et al. Cardiovascular Safety of Degarelix Versus Leuprolide in Patients With Prostate Cancer: The Primary Results of the PRONOUNCE Randomized Trial. Circulation. 2021. Peer-reviewed study
- Frampton JE, Lyseng-Williamson KA. Degarelix. Drugs. 2009. Peer-reviewed study
- Klotz L, Boccon-Gibod L, Shore ND, et al. The efficacy and safety of degarelix: a 12-month, comparative, randomized, open-label, parallel-group phase III study in patients with prostate cancer. BJU Int. 2008. Peer-reviewed study
- Carter NJ, Keam SJ. Degarelix: a review of its use in patients with prostate cancer. Drugs. 2014. Peer-reviewed study