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approvedSexual Health

Cetrorelix

Also known as: Cetrotide, Cetrorelix Acetate, SB-75, D-20761

Cetrorelix (Cetrotide) is an FDA-approved synthetic decapeptide GnRH antagonist widely used in assisted reproductive technology to prevent premature LH surges during controlled ovarian stimulation. It offers both a daily 0.25 mg dose and a single 3 mg depot injection that provides sustained LH suppression for up to 4 days. Cetrorelix has been investigated beyond IVF for conditions including endometriosis, uterine fibroids, and benign prostatic hyperplasia.

3 cited references·6 researched benefits

Quick Answer

Cetrorelix (Cetrotide) is an FDA-approved GnRH antagonist used in IVF to prevent premature ovulation. It competitively blocks pituitary GnRH receptors, immediately suppressing LH and FSH release without the initial hormonal flare of GnRH agonists. Available as a daily 0.25 mg injection or a single 3 mg depot dose, cetrorelix has a dose-dependent half-life of 5-60 hours. It is one of the two most widely used GnRH antagonists in reproductive medicine alongside ganirelix.

Key Facts

Mechanism
Cetrorelix competitively binds to GnRH receptors (GnRHR) on anterior pituitary gonadotroph cells with high affinity, preventing endogenous GnRH from activating the receptor. This produces immediate, dose-dependent suppression of gonadotropin (LH and FSH) secretion. At the 0.25 mg daily dose, LH suppression is maintained for approximately 24 hours; the 3 mg depot dose achieves sustained suppression for up to 96 hours by forming a subcutaneous depot that slowly releases the peptide. Cetrorelix does not activate the receptor (pure antagonist), so there is no initial flare of gonadotropin release. LH and FSH levels recover rapidly within 24-48 hours after the last dose.
Research Status
approved
Half-Life
~5-60 hours (dose-dependent; ~5h at 0.25 mg, ~20-60h at 3 mg depot)
Molecular Formula
C₇₀H₉₂ClN₁₇O₁₄
Primary Use
Sexual Health
Table of Contents

Benefits

  • Prevents premature LH surge during controlled ovarian stimulation for IVFstrong
  • Immediate onset of gonadotropin suppression without hormonal flarestrong
  • Single 3 mg depot dose option reduces injection burden for patientsstrong
  • Lower risk of ovarian hyperstimulation syndrome compared to GnRH agonist protocolsmoderate
  • Investigated for endometriosis and uterine fibroid symptom managementpreliminary
  • Explored for benign prostatic hyperplasia as an alternative to GnRH agonistspreliminary

Dosage Protocols

RouteDosage RangeFrequencyNotes
Subcutaneous injection (daily protocol)0.25 mgOnce dailyStarted on stimulation day 5-7 or when lead follicle reaches 14 mm, continued daily until trigger day. Most commonly used protocol.
Subcutaneous injection (single-dose protocol)3 mgSingle injectionAdministered on stimulation day 7; provides up to 4 days of LH suppression. If trigger is delayed beyond 4 days, daily 0.25 mg doses continue until trigger.

Medical disclaimer

Dosage information is provided for educational reference only. Always follow your prescriber's instructions and consult a qualified healthcare provider before starting any peptide protocol.

Side Effects

  • Injection site reactions (erythema, swelling, pruritus)common
  • Headachecommon
  • Nauseacommon
  • Ovarian hyperstimulation syndrome (when used in IVF protocols)serious
  • Systemic hypersensitivity or anaphylaxis (rare, related to mannitol excipient)serious

Frequently Asked Questions

What is cetrorelix used for?
Cetrorelix is primarily used in IVF (in vitro fertilization) to prevent premature ovulation. During controlled ovarian stimulation, multiple follicles are grown using FSH injections. Without LH suppression, the body's natural LH surge would trigger premature ovulation, causing egg loss before retrieval. Cetrorelix blocks this LH surge, giving fertility doctors control over the timing of ovulation trigger and egg retrieval. It is also being investigated off-label for endometriosis, uterine fibroids, and benign prostatic hyperplasia.
What is the difference between the 0.25 mg daily and 3 mg single-dose protocols?
The 0.25 mg daily protocol requires one injection per day starting mid-stimulation, offering flexibility in cycle management. The 3 mg single-dose protocol requires only one injection that provides LH suppression for up to 4 days, reducing injection burden. If the stimulation cycle extends beyond 4 days after the single dose, daily 0.25 mg injections are added. Clinical outcomes (pregnancy rates, oocyte yield) are comparable between protocols; the choice depends on patient preference, cycle dynamics, and physician practice patterns.
How quickly does cetrorelix suppress LH?
Cetrorelix provides rapid LH suppression — serum LH levels decrease significantly within 1-2 hours of injection, with maximal suppression achieved within 4-8 hours. This is a key advantage over GnRH agonist protocols, which require 2-3 weeks of administration to achieve pituitary desensitization and gonadotropin suppression. The rapid onset means cetrorelix can be started later in the stimulation cycle, shortening treatment duration.

References

  1. 1
    Cetrorelix: a review of its use in female infertility(2000)PubMed ↗
  2. 2
    Efficacy and safety of cetrorelix in IVF: a systematic review of clinical trials(2002)PubMed ↗
  3. 3
    The GnRH antagonist cetrorelix: a review of its pharmacology and clinical use in reproductive medicine(2004)PubMed ↗

Latest Research

Last updated: 2026-02-19