Cetrorelix
Also known as: Cetrotide, Cetrorelix acetate, SB-75
A GnRH antagonist used during IVF ovarian stimulation to prevent a premature LH surge. FDA-approved as Cetrotide (2000); generics exist. Prescription drug.
Last updated
Mechanism of Action
Cetrorelix is a synthetic decapeptide that competitively blocks GnRH receptors on the pituitary. Unlike GnRH agonists, it produces no initial flare: LH and, to a lesser degree, FSH secretion fall within hours of a dose. During controlled ovarian stimulation this prevents the premature LH surge that would trigger early ovulation, so the follicles can be matured and the oocytes retrieved at a planned time. The suppression is dose-dependent and reverses after the drug is stopped.
- Half-life
- ~5-20 hours at the 0.25 mg dose; longer at higher doses
- Administration Routes
- Subcutaneous
- Research Status
- Clinical
Reported Benefits
- Inhibition of premature LH surges in women undergoing controlled ovarian stimulation
- Shorter treatment course than long GnRH-agonist protocols
- Fast onset with no hormonal flare
Potential Side Effects
- Injection-site reactions (redness, swelling, itching)
- Ovarian hyperstimulation syndrome (OHSS), related to the stimulation cycle
- Nausea and headache
- Rare severe hypersensitivity or anaphylactoid reactions
Common Dosing
In the labeled regimen a 0.25 mg subcutaneous injection is given once daily during the stimulation phase, starting partway through follicle stimulation and continuing until the day of the ovulation trigger. A single 3 mg dose option has been discontinued in the US. Timing is set by the fertility clinic based on ultrasound and hormone monitoring. Dosing is set and supervised by the prescribing clinician.
The dosing information above is aggregated from research literature and anecdotal community reports for educational purposes only. It is not a recommendation, prescription, or medical advice. Peptides are sold as research chemicals only and are not intended for human use.
Contraindications
- Hypersensitivity to cetrorelix, extrinsic peptide hormones, GnRH analogs or mannitol
- Known or suspected pregnancy
- Breastfeeding
No documented stacking partners for Cetrorelix yet.
- View
Ovarian stimulation with HMG: results of a prospective randomized phase III European study comparing the luteinizing hormone-releasing hormone (LHRH)-antagonist cetrorelix and the LHRH-agonist buserelin. European Cetrorelix Study Group
2000
- View
Safety and efficacy of a 3 mg dose of the GnRH antagonist cetrorelix in preventing premature LH surges: report of two large multicentre, multinational, phase IIIb clinical experiences
2003
- View
The LHRH antagonist cetrorelix: a review
2000