Cetrorelix
An FDA-approved synthetic GnRH antagonist that rapidly suppresses LH and FSH to prevent premature ovulation during IVF cycles.
Cetrorelix is a synthetic GnRH (gonadotropin-releasing hormone) antagonist peptide used in assisted reproductive technology to prevent premature luteinizing hormone (LH) surges during controlled ovarian stimulation. By competitively blocking pituitary GnRH receptors, it rapidly suppresses LH and FSH release without the initial hormonal flare seen with GnRH agonists, allowing more precise timing of oocyte retrieval. It is marketed as Cetrotide, an FDA-approved prescription medication used under specialist supervision in fertility treatment.
Class
Synthetic decapeptide GnRH antagonist
Half-life
~62 hours
Routes
Subcutaneous, Nasal (investigational)
Category
Hormone & Reproductive
Researched benefits
What it's studied for
Prevents premature LH surges
Cetrorelix competitively blocks pituitary GnRH receptors to rapidly suppress LH release, preventing premature ovulation during controlled ovarian stimulation and allowing precise timing of oocyte retrieval in IVF and ICSI cycles.
No initial hormonal flare
Unlike GnRH agonists (triptorelin, leuprolide), the antagonist mechanism produces immediate receptor blockade without the transient LH/FSH surge, avoiding the weeks-long downregulation period and shortening total cycle length.
HPG axis suppression
By suppressing both LH and FSH, cetrorelix provides controlled hormonal suppression of the hypothalamic-pituitary-gonadal axis, a property explored for LH/FSH reduction and testosterone management contexts.
Reduced OHSS risk
In a network meta-analysis of IVF/ICSI cycles in women with PCOS, cetrorelix ranked highest (96.9% probability) for reducing the risk of ovarian hyperstimulation syndrome relative to other GnRH agonist and antagonist regimens.
Flexible dosing
Retrospective data suggest dosing can be tailored to patient characteristics, with half-dose protocols yielding more retrieved oocytes and available embryos than full-dose while maintaining comparable pregnancy outcomes.
Mechanism
How it works
Cetrorelix is a competitive antagonist at the GnRH (gonadotropin-releasing hormone) receptor on the pituitary gonadotroph cells. Under normal physiology, hypothalamic GnRH pulses stimulate these receptors to release LH and FSH, which drive gonadal steroidogenesis and, in women, the mid-cycle LH surge that triggers ovulation. By occupying the receptor without activating it, cetrorelix immediately blocks this signaling.
Because the blockade is competitive and immediate, cetrorelix suppresses LH and FSH secretion within hours and without the initial stimulatory 'flare' that GnRH agonists cause. GnRH agonists first hyperstimulate then downregulate the receptor over one to two weeks, whereas antagonists like cetrorelix can be introduced mid-stimulation to abruptly prevent an LH surge, reducing the overall treatment duration.
In the IVF setting, this controlled suppression allows exogenous gonadotropins to mature multiple follicles while preventing premature ovulation, so that oocyte retrieval can be precisely timed after a controlled trigger. Cetrorelix and ganirelix share this mechanism and are considered pharmacologically equivalent as GnRH antagonists, differing mainly in formulation and dosing schedule.
Dosing protocols
Dosing & administration
Dosing reflects protocols reported in research and community literature for educational purposes. It is not medical advice or a recommendation. Most peptides here are not approved for human use.
Reconstitution
Cetrotide is supplied as a lyophilized powder with accompanying sterile water or diluent per the manufacturer's prescribing information; it is reconstituted immediately before subcutaneous injection.
Multiple-dose protocol
- Dose
- 0.25 mg
- Frequency
- Once daily
- Timing
- During ovarian stimulation, started per treating physician's schedule
- Duration
- Until the day of ovulation trigger
- Route
- Subcutaneous
Standard FDA-labeled multiple-dose regimen for preventing premature LH surges during controlled ovarian stimulation.
Single-dose protocol
- Dose
- 3 mg
- Frequency
- Single injection
- Timing
- Administered per protocol timing during stimulation
- Duration
- One dose; supplemental 0.25 mg doses may be added per physician
- Route
- Subcutaneous
FDA-labeled single-dose alternative; timing, trigger criteria, and any supplemental dosing are determined by the reproductive endocrinologist.
- Specific timing, trigger criteria, and supplemental dosing schedules are determined by the treating reproductive endocrinologist per full FDA prescribing information.
- Retrospective data (n=316) found half-dose cetrorelix yielded more retrieved oocytes and available embryos than full-dose, with comparable pregnancy and live birth rates, suggesting dose flexibility for patient-specific optimization.
- Cetrorelix is a prescription-only fertility medication and should be used only under specialist reproductive endocrinology supervision.
Evidence
Research & clinical studies (5)
GnRH Agonists and Antagonists in IVF/ICSI Cycles of PCOS Women: A Network Meta-Analysis
Across 20 RCTs (2,400 patients), cetrorelix had the highest probability ranking (96.9%) for reducing ovarian hyperstimulation syndrome risk, while leuprorelin ranked highest for clinical pregnancy and live birth rates.
PMID 42152207Hydrogel and oleogel formulation of the decapeptide cetrorelix acetate for nasal administration
Both oleogel and hydrogel nasal formulations were developed, with the hydrogel showing superior bioavailability (5.3%) and prolonged absorption over 24 hours, suggesting a viable non-invasive delivery alternative.
PMID 41722737Effects of half-dose and full-dose GnRH antagonists on IVF-ET outcomes: a retrospective study
In 316 IVF-ET cycles, half-dose cetrorelix yielded significantly more retrieved oocytes and available embryos than full-dose, with comparable pregnancy and live birth rates and higher clinical pregnancy rate in patients with BMI ≥25.
PMID 34706665Comparison of the effects of Duphaston and Cetrotide on oocyte and embryo quality in women undergoing ICSI: a cross-sectional study
In 200 ICSI patients, cetrorelix effectively prevented premature LH surge with follicle counts, oocyte maturation, and viable embryo numbers comparable to oral dydrogesterone (Duphaston).
PMID 33349806Comparison of Chitosan-Poloxamer Nanoparticles and Poloxamer-based In-Situ Forming Gel for Nose-to-Brain Delivery of Cetrorelix: In Vitro and Pharmacokinetic Studies in Rats
Compared nanoparticle and in-situ gel systems for nose-to-brain delivery of cetrorelix in rats, characterizing in vitro release and pharmacokinetic behavior of the delivery platforms.
PMID 42243608Safety
Side effects & considerations
Commonly reported effects
Contraindications & cautions
- Pregnancy
- Hormone-sensitive cancers (use with caution)
- Renal impairment
Cetrorelix carries a moderate risk profile. It is contraindicated in pregnancy and should be used with caution in patients with hormone-sensitive cancers or renal impairment. Use only under qualified medical supervision and review all considerations before use.
FAQ
Cetrorelix — common questions
What is Cetrorelix?
Cetrorelix is a synthetic GnRH antagonist peptide used in assisted reproductive technology to prevent premature LH surges during controlled ovarian stimulation. By competitively blocking pituitary GnRH receptors, it rapidly suppresses LH release without the initial hormonal flare seen with GnRH agonists, allowing precise timing of oocyte retrieval.
What is Cetrorelix primarily studied for?
Its main established use is preventing premature ovulation in IVF and ICSI cycles. Research signals also cover HPG axis suppression, LH/FSH reduction, controlled ovarian stimulation support, and testosterone management.
How is Cetrorelix dosed?
Per FDA labeling for Cetrotide, there are two subcutaneous protocols: a multiple-dose protocol of 0.25 mg once daily during ovarian stimulation, and a single-dose protocol of 3 mg as one injection. Exact timing and any supplemental doses are set by the treating reproductive endocrinologist.
How does Cetrorelix differ from ganirelix?
Both are competitive GnRH receptor antagonists used in the same IVF indication and are pharmacologically equivalent in mechanism. Differences relate to proprietary formulation, dosing schedule, and regional market availability. Neither requires the weeks-long downregulation period of GnRH agonist protocols.
What are the side effects of Cetrorelix?
It has a moderate risk profile. Reported contraindications and cautions include pregnancy, hormone-sensitive cancers (with caution), and renal impairment. Consult a qualified healthcare professional before use.
Is Cetrorelix FDA approved?
Yes. Cetrorelix is FDA approved as Cetrotide (NDA 021036, June 3, 1999) for preventing premature LH surges in controlled ovarian stimulation. It is prescription only and used under specialist supervision.
