FDA Approved Sexual & Reproductive Health

Cetrorelix

also known as: Cetrotide

Merck Serono's Cetrotide — a GnRH antagonist used during IVF controlled ovarian stimulation to block premature LH surges. Unlike GnRH agonists, produces immediate gonadotropin suppression without a flare, shortening IVF cycles.

A synthetic decapeptide GnRH-receptor antagonist with five non-natural amino acid substitutions, producing rapid competitive blockade of pituitary GnRH receptors. Used in IVF controlled ovarian stimulation to prevent premature LH surges in a simpler and shorter protocol than GnRH-agonist downregulation. FDA-approved as Cetrotide in 2000; the first GnRH antagonist approved for reproductive medicine.

Mechanism of action

Competitive antagonism at pituitary GnRH receptors — rapid onset blocks endogenous GnRH binding within hours, immediately suppressing LH and FSH release without the initial agonist flare. Effect wanes rapidly after discontinuation, permitting hCG trigger for ovulation.

Primary uses

  • Prevention of premature LH surge during IVF controlled ovarian stimulation

Typical dosing

0.25 (daily) or 3 (single-dose) mg daily SC (flexible or fixed protocol) or single SC dose (subcutaneous)

Flexible protocol: 0.25 mg SC daily starting when the lead follicle reaches ~14 mm or estradiol indicates imminent LH surge risk. Single-dose 3 mg on stimulation day 7–8. Continued until day of hCG trigger.

Regulatory status

FDA-approved as Cetrotide (cetrorelix acetate, Merck Serono / EMD Serono, approved 2000) for inhibition of premature LH surges in women undergoing controlled ovarian stimulation for assisted reproduction. Two doses available: 0.25 mg for daily administration and 3 mg for single-dose use.

References

  1. [fda-pi] Cetrotide (cetrorelix acetate for injection) Prescribing Information. EMD Serono.
  2. [pubmed] Al-Inany HG, et al. "Gonadotrophin-releasing hormone antagonists for assisted reproductive technology." Cochrane Database Syst Rev, 2016;4:CD001750.

Related peptides

Ganirelix

Organon/Merck's Ganirelix Acetate (formerly Antagon; Orgalutran internationally) — a GnRH antagonist functionally equivalent to cetrorelix for IVF LH-surge prevention, dosed as a daily fixed 250 mcg SC injection.

Degarelix

Ferring's Firmagon — a GnRH antagonist for advanced prostate cancer that achieves castrate testosterone within 3 days, eliminating the clinical flare risk of GnRH-agonist therapy in patients with symptomatic bone metastases or impending spinal cord compression.

Gonadorelin

The native GnRH decapeptide — the hypothalamic signal that drives LH/FSH release and downstream testosterone/estradiol production. Historically FDA-approved (Factrel, Lutrepulse), now widely used in TRT-adjacent fertility protocols as a testicular-preservation alternative to HCG.

Follitropin alfa

EMD Serono's Gonal-f — the first recombinant human FSH approved by the FDA (1997). Used for ovulation induction, IVF controlled ovarian stimulation, and male hypogonadotropic hypogonadism fertility induction.

HCG

An FDA-approved fertility and hypogonadism medication commonly discussed in peptide and TRT communities for post-cycle recovery and testicular preservation during testosterone therapy.
Disclaimer

This entry is for educational purposes only and does not constitute medical advice. Dosing information reflects published regulatory or research data and is not a recommendation. Many compounds described here are not approved for human use in the United States. Consult a licensed medical professional before considering any peptide therapy.