Cetrorelix (Cetrotide)

Summary

Cetrorelix is an FDA approved GnRH antagonist (Cetrotide, approved August 2000), a drug that blocks the brain hormone signal that triggers ovulation, given as a 0.25 mg daily injection under the skin during ovarian stimulation to stop a premature LH surge (the hormone spike that releases eggs) before egg retrieval. In the pivotal European phase 3 trial it produced clinical pregnancy rates comparable to the older long protocol using the agonist buserelin (22.3% versus 25.8% per attempt) with far fewer cases of moderate to severe ovarian hyperstimulation syndrome, a dangerous overreaction of the ovaries (1.1% versus 6.5%). A Cochrane review (a rigorous pooled analysis) of 73 trials confirms antagonists and agonists give the same live birth rate. It is a routine fertility clinic drug, not a research peptide.

What is Cetrorelix?

Cetrorelix is a gonadotropin releasing hormone (GnRH) antagonist, synthetic decapeptide. It is also known as Cetrotide, cetrorelix acetate, SB-75, NS-75A.

How does it work?

Cetrorelix competitively occupies GnRH receptors on pituitary gonadotrophs and blocks the pulsatile GnRH signal, so LH and FSH secretion falls within hours without the initial flare seen with GnRH agonists. During ovarian stimulation this prevents the estradiol driven LH surge that would trigger ovulation prematurely. Suppression is dose dependent and reverses within days after the last injection.

FDA-approved uses of Cetrorelix

Yes, since 2000. The Cetrotide label has one use: inhibiting premature LH surges (the hormone spike that triggers ovulation) in women undergoing controlled ovarian stimulation, as in IVF and other assisted reproduction cycles. Blocking pituitary GnRH receptors, the switch the brain uses to release LH, keeps LH from rising before the eggs are ready, so ovulation can be timed with an hCG trigger shot. It is prescription only, and generic cetrorelix kits are also on DailyMed. [4]

What does the evidence say about Cetrorelix?

Randomized trials in IVF support both the daily 0.25 mg regimen and a single 3 mg regimen. The pivotal European phase 3 trial versus buserelin showed comparable pregnancy rates with fewer gonadotropin ampoules, shorter stimulation, and markedly less ovarian hyperstimulation syndrome. A single dose trial (n = 115) versus triptorelin showed similar outcomes. Cochrane 2016 (73 RCTs, 12,212 women, all GnRH antagonists): live birth odds ratio 1.02 and ovarian hyperstimulation syndrome odds ratio 0.61 versus agonist protocols.

Human evidence

Albano 2000 (randomized phase 3, cetrorelix 0.25 mg daily versus long buserelin protocol): clinical pregnancy per attempt 22.3% versus 25.8%, ovarian hyperstimulation syndrome grade II or III in 1.1% versus 6.5%, and fewer hMG ampoules and stimulation days with cetrorelix. Olivennes 2000 (n = 115, single 3 mg cetrorelix dose versus triptorelin long protocol): no premature LH surges in the cetrorelix group and comparable pregnancy rates with shorter treatment. Cochrane 2016 across antagonists: no difference in live birth (OR 1.02, 95% CI 0.85 to 1.23) and lower OHSS (OR 0.61, 95% CI 0.51 to 0.72).

Animal evidence

Preclinical studies in rodents and primates established rapid reversible gonadotropin suppression, and cetrorelix was also studied in animal models of hormone dependent tumors and benign prostatic hyperplasia before development focused on fertility. Reproductive toxicology showed pregnancy loss when given during early gestation.

Key studies

Conditions studied

Is Cetrorelix legal in the United States?

FDA and compounding status

FDA approved prescription drug (Cetrotide, approved August 11, 2000) to inhibit premature LH surges in women undergoing controlled ovarian stimulation. Commercially available as a 0.25 mg kit, so it is not eligible for routine compounding and is not on any 503A bulks list. Not a research chemical.

WADA status

Not WADA prohibited. Not named on the current prohibited list. Athletes should still confirm against the list in force for their season.

Regulatory timeline

No regulatory events recorded.

Full tracker for Cetrorelix or the category-wide tracker.

Cetrorelix dose on the FDA label

Doses below are quoted from the FDA label for its approved uses, plus the doses used in the pivotal trials where noted. The prescriber sets the dose; PeptideAgent does not recommend doses or protocols.

FDA label (Cetrotide 0.25 mg, DailyMed): after gonadotropin stimulation starts on cycle day 2 or 3, 0.25 mg is injected subcutaneously once daily during the early to mid follicular phase, beginning on stimulation day 5 (morning or evening) or day 6 (morning) and continuing daily until the day of hCG administration. The label says hCG should not be given if the ovaries respond excessively, to lower the chance of ovarian hyperstimulation syndrome. A single 3 mg regimen was studied in trials but is not on the current US label.

Routes reported

What are the side effects and interactions of Cetrorelix?

Side effects

Interactions

Contraindications

How do people access Cetrorelix legally?

Typical cost: Roughly 100 to 250 USD per 0.25 mg dose at US pharmacies, with a typical cycle using 4 to 6 doses. Coverage depends on fertility medication benefits; many patients pay cash as part of an IVF medication package. Prices verified on the last verified date.

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Frequently asked questions

Decisions about starting, stopping, or combining any treatment belong with a licensed clinician who knows your history.

Sources

Numbered citations above point to these primary sources. PubMed entries link to the indexed abstract.