Clinical / Pharmaceutical

Cetrorelix

Cetrotide · cetrorelix acetate

GnRH antagonist FDA-approved to prevent premature LH surge in controlled ovarian stimulation. Cetrotide 0.25 mg is a lyophilized vial plus 1 mL sterile water in a prefilled syringe — mix and inject the contents. First dose is supposed to happen under medical supervision (anaphylaxis risk). This is a clinic kit, not a research-chem analog.

WADA (S2) — prohibited in sport at all times
Reviewed by CalcMyPeptide Editorial Team
Last updated: April 2026Evidence: High1 peer-reviewed citation
Typical research dose
0.25 mg SC once daily (Cetrotide kit) until hCG trigger
Frequency
1× daily during stimulation (IVF)
Half-life
~5 h (0.25 mg single SC); longer with daily dosing (Cetrotide PI)
Common vials
0.25 mg
CAS
120287-85-6
Molecular weight
~1.43 kDa
Dose it
0.25 mg + 1 mL BAC water → 0.25 mg/mL · 250 mcg ≈ 100 units (U-100)
Open in calculator

Mechanism of Action

Cetrorelix is a GnRH-receptor antagonist. Cetrotide 0.25 mg is a lyophilized vial plus 1 mL sterile water in a prefilled syringe. Reconstitute with the supplied solvent, swirl (do not shake), inject the contents SC. First injection under medical supervision — anaphylaxis is a labeled risk.

Single 0.25 mg t½ ~5 hours; repeat daily dosing lengthens apparent t½. The 3 mg single-dose regimen is a different kit.

Source: Cetrotide PI (EMD Serono); DailyMed cetrorelix acetate

Use the kit solvent. Inject the vial.

Labeled math is 0.25 mg in 1 mL. You are not titrating mcg on an insulin syringe for the 0.25 mg kit — you deliver the reconstituted contents. Research bulk powder is a different product; this page defaults to the Cetrotide kit.

Dosing Protocol

Typical Dose0.25 mg SC once daily (Cetrotide kit) until hCG trigger
Frequency1× daily during stimulation (IVF)
Half-Life~5 hours (0.25 mg single SC; longer with repeat doses)
Common Vial Sizes0.25 mg

Dosing Protocols

Cetrotide 0.25 mg (labeled multiple-dose)

Dose
0.25 mg SC
Frequency
Once daily from stim day 5 or 6 until hCG
Note: IVF only, specialist-prescribed.

Body-Weight Dosing Reference

Estimated doses extrapolated from the published research range of 250–250 mcg/day (referenced to 70 kg / 154 lb). These are approximations — consult a qualified healthcare provider for personalised guidance.

WeightLowTargetHigh
120 lb(54 kg)193 mcg193 mcg193 mcg
140 lb(63 kg)225 mcg225 mcg225 mcg
160 lb(73 kg)261 mcg261 mcg261 mcg
180 lb(82 kg)293 mcg293 mcg293 mcg
200 lb(91 kg)325 mcg325 mcg325 mcg
220 lb(100 kg)357 mcg357 mcg357 mcg
250 lb(113 kg)404 mcg404 mcg404 mcg

💉 For exact syringe units based on your vial concentration, use the Cetrorelix Reconstitution Calculator →

Administration

Route
Subcutaneous (lower abdomen typical)
Timing
Same time daily as directed.
Fasting Required?
No — food timing not critical

Expected Timeline

Hours
LH suppression without agonist flare.

Who Is It For?

IVF LH-surge blockade

High

This is the labeled job. Not a research-chem GnRH toy.

Reconstitution Example

Vial
0.25 mg
Diluent
1 mL
Concentration
0.25 mg/mL
Per Unit (100u syringe)
2.5 mcg
Dose of 250 mcg = 100 units on a 100-unit insulin syringe
🧮 Calculate Your Exact Cetrorelix Dose →

Safety & Considerations

Prescription. Pregnancy contraindicated. Hypersensitivity including anaphylaxis. OHSS is a stimulation-cycle risk. First dose supervised.

Regulatory & Legal Status

FDA Status (US)
Approved

FDA-approved as Cetrotide® for prevention of premature LH surge in COS/IVF

WADA Status (2026)
Prohibited (S2)

Competitive athletes subject to anti-doping controls should not use Cetrorelix.

Classification

Prescription Drug

US Compounding: Not eligible / not available

⚠️ This information is for educational purposes only and may not reflect the most current regulatory updates. Always verify with official FDA, WADA, and jurisdiction-specific sources before use.

Dosing Quick Reference

Cetrorelix— Dosing Guide
Dose Range
0.25 mg SC once daily (Cetrotide kit) until hCG trigger
Half-Life
~5 hours (0.25 mg single SC; longer with repeat doses)
Frequency
1× daily during stimulation (IVF)
Route
Subcutaneous
0.25 mg vial
💧 1 mL BAC water📐 0.25 mg/mL💉 2.5 mcg/unit (100u syringe)
Clinical / Pharmaceuticalcalcmypeptide.com

Frequently Asked Questions

How much water for Cetrotide 0.25 mg?▼
The 1 mL in the kit. Do not substitute BAC water unless a pharmacist has issued a different product.
Can I split the vial across days?▼
The 0.25 mg kit is a single daily dose, used immediately after mixing per SmPC/PI.

References

  1. EMD Serono “Cetrotide (cetrorelix acetate) prescribing information.” US PI (current).

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