Sexual & reproductive GnRH antagonist
Cetrorelix
Regulatory status
Status at a glance
503A compounding status
Not nominated
We found no pending nomination for the 503A bulks list. Unless the substance has another legal pathway (for example, a USP monograph or use in an FDA-approved drug), 503A pharmacies generally may not compound with it.
- FDA approval
- An FDA-approved product contains this peptide
- 503B outsourcing
- Not determined
- Anti-doping (WADA)
- Not on the WADA Prohibited List
- DEA schedule
- Not a controlled substance
About peptide status
Most peptides discussed here are not FDA-approved for any use, and products labeled “research use only” are not for human use. Removal from Category 2 does not authorize compounding. PCAC votes are non-binding recommendations; FDA and HHS make the final decisions.
This is not medical or legal advice, and we do not publish dosing, sourcing or reconstitution information. Talk with a licensed clinician before using any peptide.
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Key takeaway
Cetrorelix is a synthetic ten-amino acid peptide that blocks the GnRH receptor in the pituitary gland, shutting down the hormone signals that would otherwise trigger early ovulation. It is FDA-approved as Cetrotide, a subcutaneous injection used during IVF to stop a premature LH surge so that eggs can mature and be collected on schedule. It remains a standard part of modern IVF stimulation, valued for acting quickly and for lowering the risk of ovarian hyperstimulation compared with older protocols.
At a glance
- FDA status
- FDA-approved peptide, sold as Cetrotide, given as a subcutaneous injection during fertility treatment
- How it works
- GnRH (gonadotropin-releasing hormone) antagonist that rapidly blocks pituitary signaling
- Approved for
- Preventing premature ovulation (an early LH surge) in women undergoing controlled ovarian stimulation for IVF
- Key benefit
- Shortens treatment and lowers the risk of severe ovarian hyperstimulation syndrome, compared with the older long agonist protocol
- Evidence strength
- FDA approved
Summary
Cetrorelix is an FDA-approved GnRH antagonist sold as Cetrotide. Learn how it prevents early ovulation during IVF stimulation and where it fits.
What is cetrorelix?
Cetrorelix is a synthetic peptide made of ten amino acids that acts as a GnRH antagonist, a drug that blocks the receptor for gonadotropin-releasing hormone in the pituitary gland. Its FDA-approved form is sold as Cetrotide and is used during in vitro fertilization (IVF).
It is given as a small subcutaneous (under-the-skin) injection, usually in the abdomen, during the stimulation phase of an IVF cycle. Its job is narrow and practical: to keep the body from ovulating too early so that the growing eggs can be retrieved at the right time.
The history of cetrorelix
Cetrorelix came out of a long effort to improve how IVF controls ovulation. For years the standard approach used GnRH agonists, drugs that first overstimulate the pituitary and then, after about two weeks, exhaust and quiet it. That worked, but it was slow and caused an initial hormone "flare" and estrogen-withdrawal side effects. Researchers wanted a drug that would switch the signal off directly and immediately.
GnRH antagonists were the answer, and cetrorelix was among the first to reach the clinic for fertility care. The FDA approved Cetrotide in 2000, giving IVF a shorter, simpler way to prevent premature ovulation. The antagonist approach has since become a mainstream option for ovarian stimulation.
How does cetrorelix work?
Cetrorelix works by blocking the pituitary receptor that normally triggers ovulation. Gonadotropin-releasing hormone is released in pulses from the hypothalamus and tells the pituitary to secrete luteinizing hormone (LH) and follicle-stimulating hormone (FSH). During IVF, as stimulated follicles grow and estrogen climbs, the body can launch a premature LH surge that makes the ovaries release their eggs too early and ruins the cycle. Cetrorelix is a decapeptide that competes with natural GnRH for its receptor and occupies it, which rapidly suppresses LH and FSH release.
The key difference from GnRH agonists is timing:
| Feature | GnRH agonists | Cetrorelix (GnRH antagonist) |
|---|---|---|
| First effect on the pituitary | Stimulate it, causing a temporary surge | No initial flare |
| Suppression | Downregulate it over a couple of weeks | Immediate, dose-dependent, and reversible |
That is why cetrorelix can be started later in the stimulation cycle and used for only a few days. It is given as a 0.25 mg dose injected daily. A single 3 mg dose was also studied, but only the 0.25 mg product is sold in the U.S.
The effect is reliable. According to PubMed, in a multicenter randomized trial a single 3 mg dose of cetrorelix prevented an LH surge in every patient studied, with shorter stimulation and fewer gonadotropin ampules than the long agonist protocol.
Is it FDA-approved?
Editor’s note
Status: FDA-approved peptide, sold as Cetrotide, given as a subcutaneous injection during fertility treatment
Category: FDA-approved · Primary body area: Sexual & reproductive
Yes. The FDA approved cetrorelix (Cetrotide) in 2000 for the inhibition of premature LH surges in women undergoing controlled ovarian stimulation. It is a prescription product used under the supervision of a fertility specialist, and it is approved specifically for this fertility use rather than as a general hormone treatment.
What is cetrorelix prescribed for?
Cetrorelix is prescribed to prevent premature ovulation during an IVF cycle. After a woman begins gonadotropin injections to grow multiple follicles, cetrorelix is added to hold back the LH surge until the eggs are mature, at which point a separate trigger shot is given and the eggs are retrieved. It is not a fertility drug in the sense of stimulating egg growth; it is the brake that keeps the timing under the clinic's control. It is contraindicated in:
- Pregnancy
- Women with severe kidney impairment
- Women with known hypersensitivity to the drug or to other GnRH analogs
Cetrorelix is used only within a monitored treatment cycle.
What are the side effects?
The most common effects are mild and local. They include:
- Injection-site reactions such as redness, itching, or swelling
- Nausea
- Headache
Serious effects are uncommon but worth knowing:
- Ovarian hyperstimulation syndrome (OHSS), a risk of the overall IVF stimulation; according to PubMed, a Cochrane review found that antagonist protocols reduced OHSS compared with the long agonist protocol, with no conclusive difference in live birth rate
- Allergic or hypersensitivity reactions, which can rarely be severe
Sources: FDA prescribing information for Cetrotide (cetrorelix acetate); DrugBank (cetrorelix); the single-dose cetrorelix IVF trial (Olivennes et al., Fertility and Sterility, 2000, DOI: 10.1016/s0015-0282(99)00524-5); and a Cochrane systematic review of GnRH antagonists for assisted conception (Al-Inany et al., Cochrane Database of Systematic Reviews, 2016, DOI: 10.1002/14651858.CD001750.pub4), both indexed on PubMed. This document is educational and does not constitute medical advice.
Registered human trials
0 registered human trials on ClinicalTrials.gov that we reviewed
Sources
- [1]
Cetrotide (PDF)
- [2]
- [3]
- [4]
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