Cetrorelix
Also known as: Cetrotide
Molecular Identifiers
Molecular Formula
C70H92ClN17O14
CAS Number
120287-85-6
PubChem CID
25074887UNII
8AO662J5HE
Molecular Weight
1431.04 Da
Overview
GnRH receptor antagonist that competitively blocks LH and FSH release from the pituitary gland. Used in assisted reproduction protocols to prevent premature ovulation and in gonadal suppression research.
FDA-approved as Cetrotide for prevention of premature ovulation in controlled ovarian stimulation protocols for in vitro fertilization (IVF). Third-generation GnRH antagonist.
Cetrorelix competitively blocks the GnRH receptor in the pituitary, rapidly and reversibly suppressing LH and FSH release. Unlike GnRH agonists, it does not cause an initial flare-up effect, which made it a key tool in in vitro fertilization protocols to prevent the premature LH surge during controlled ovarian stimulation. It is also studied in endometriosis, fibroids, and experimental gonadal suppression.
It is an FDA-approved drug, marketed as Cetrotide for assisted reproduction. In other contexts, such as bodybuilding or hormonal investigation, it appears in off-label use and outside the authorized clinical context. Administration is subcutaneous, with a low daily dose (0.25 mg) or a single high dose (3 mg) depending on the IVF protocol.
It was developed by ASTA Medica/Serono as a third-generation GnRH antagonist, containing multiple D-amino acids and non-natural amino acids that increase metabolic stability. Its safety profile in IVF is well documented, with adverse effects limited to local reactions, flushing, and headache.
Within the HPG axis, Cetrorelix is the GnRH antagonist — immediate and reversible suppression of LH/FSH without the flare characteristic of agonists. It shares the receptor with gonadorelin (endogenous GnRH, short stimulatory action) and triptorelin (long-acting agonist that desensitizes after the flare), but with the opposite effect. Compared with kisspeptin-10 (upstream of GnRH) and hCG (which mimics LH at the gonad), it works at the pituitary level and in a blocking, not stimulating, mode.
Ac-D-Nal(2)-D-Cpa-D-Pal(3)-Ser-Tyr-D-Cit-Leu-Arg-Pro-D-Ala-NH₂ Contains multiple D-amino acids and unnatural amino acids
Half-life
~62 hours
Administration Route
Subcutaneous
Category
Hormonal Regulation
Mechanism of Action
- Competitive antagonism of the GnRH receptor in the pituitary gland
- Rapid and reversible suppression of LH and FSH
- Prevention of premature LH surge
- Blockade of gonadotropin release without initial stimulation phase
- Dose-dependent effect on gonadal suppression
Dosage Protocol
Data compiled from the literature. This does not constitute medical advice.
| Parameter | Value |
|---|---|
| Dose | 0.25-3 mg per injection |
| Frequency | Once daily (0.25 mg) or single dose (3 mg) |
| Timing | As per hormonal protocol |
| Duration | Variable per protocol (usually 3-7 days in IVF) |
Reported Side Effects
Adverse effects described in the literature. Severity and frequency vary between individuals.
- Facial flushing
- Nausea
- Headache
- Injection site reactions
- Hot flashes
Product Properties
| Purity | >98% |
| Appearance | White lyophilized powder |
| Solubility | Soluble in water and bacteriostatic water |
| Source | Solid-phase peptide synthesis (SPPS) |
| Storage | Lyophilized: -20°C for up to 2 years, 2-8°C for up to 6 months. Reconstituted: 2-8°C for up to 4 weeks. Protect from light and moisture. Avoid repeated freeze-thaw cycles. |
Presentations & Preparation
Vials of Cetrorelix found in the research market:
Reconstitution
- Diluent: Bacteriostatic water
- Volume: 1 ml per vial
- Slowly inject the diluent against the vial wall
- Gently swirl until fully dissolved
- Never shake
Storage
- Lyophilized: Refrigerated 2-8°C (may be stored at room temperature up to 25°C)
- Reconstituted: Use immediately after reconstitution
- Protect from direct light
- Use promptly after reconstitution
Scientific Studies
Published studies on Cetrorelix.
Ovarian stimulation for assisted reproduction with HMG and concomitant midcycle administration of the GnRH antagonist cetrorelix according to the multiple dose protocol: a prospective uncontrolled phase III study
Felberbaum RE, Albano C, Ludwig M, Riethmüller-Winzen H, Grigat M, Devroey P, Diedrich K
Luteinizing hormone-releasing hormone antagonist cetrorelix as primary single therapy in patients with advanced prostatic cancer and paraplegia due to metastatic invasion of spinal cord
Gonzalez-Barcena D, Vadillo-Buenfil M, Cortez-Morales A, Fuentes-Garcia M, Cardenas-Cornejo I, Comaru-Schally AM, Schally AV
Related Peptides
Argipressin
5-20 IU or 1-4 mcg/kg · As clinically needed
Gonadorelin
100-200 mcg per injection · 2-3 times per week
HCG
250-500 IU per injection · 2-3 times per week
Kisspeptin-10
1-10 mcg per injection · Per research protocol
α-MSH
0.5-2 mg per injection · Once daily or every other day
Oxytocin
10-40 IU intranasal or 50-200 mcg subcutaneous · 1-2 times daily