What is the difference between Cetrorelix and Melanotan II?

Cetrorelix: Competitive GnRH receptor antagonist; immediately blocks pituitary GnRH receptors; rapidly suppresses LH/FSH without initial flare effect; used for controlled hormonal suppression Melanotan II: Synthetic melanocortin receptor agonist (MC1R-MC5R); activates MC4R for erectile function/libido; MC1R for melanogenesis; MC3R for appetite suppression

Is Cetrorelix FDA approved?

Cetrorelix is FDA approved. This regulatory status is provided for research and educational context only.

How is Cetrorelix administered in research settings?

In research settings, Cetrorelix is typically administered via the subcutaneous route. PeptideBase does not provide dosing or administration instructions.

How is Melanotan II administered in research settings?

In research settings, Melanotan II is typically administered via the subcutaneous or intranasal routes. PeptideBase does not provide dosing or administration instructions.

Home›Research›Compare›Cetrorelix vs Melanotan II

Peptide Comparison

Cetrorelix vs Melanotan II

Name: Cetrorelix vs Melanotan II — Per-mg Price Comparison
Creator: PeptideBase
License: https://peptidebase.io/terms

Both are Reproductive & Hormonal peptides.

Cetrorelix

Cetrotide

Sexual HealthFDA ApprovedPrescription

Half-life: ~62 hours

1 providers listed

Full Cetrorelix profile →

Melanotan II

MT-II

Sexual HealthResearch Only

Half-life: ~1-2 hours

94 providers listed

Full Melanotan II profile →

Bottom line

Cetrorelix is FDA-approved, while Melanotan II is nomination withdrawn — the clearest structural difference between them.

Quick Verdict

Cetrorelix

Half-life

~62 hours

Melanotan II

Half-life

~1-2 hours

Which One Should You Choose?

Your goal	Better option
Stronger clinical evidence	Cetrorelix
Further along in FDA review	Cetrorelix
Less frequent dosing (longer half-life)	Cetrorelix
More provider options (1 vs 94)	Melanotan II

Research summary only — not medical advice. Consult a qualified provider before making any decisions.

Side-by-Side Comparison

Cetrorelix

Melanotan II

Mechanism Family

Reproductive & Hormonal

Half-life

~62 hours

~1-2 hours

FDA Status

approved

nomination withdrawn

Admin Routes

subcutaneous

subcutaneous, intranasal

Availability

Prescription

Research Only

Providers

1 listed

94 listed

Avail. Notes

FDA-approved GnRH antagonist. Brand: Cetrotide (NDA 021036, Jun 1999). Prevents premature LH surges in controlled ovarian stimulation. Prescription only.

Not FDA-approved. Not to be confused with bremelanotide (PT-141/Vyleesi, which is approved). No NDA. Sold illicitly as research chemical. FDA warns against injectable tanning products.

Research Evidence

Cetrorelix

Meta-analysis · 7 key studies · most recent 2026

Melanotan II

RCT · 2 key studies · dated evidence base — most recent 2014

Research Citations

Cetrorelix

Meta-analysis2026 · J Coll Physicians Surg Pak

GnRH Agonists and Antagonists in IVF/ICSI Cycles of PCOS Women: A Network Meta-Analysis.

Meta-analysis2023 · Hum Reprod Update

Optimal GnRH antagonist protocol for ovarian stimulation during ART: systematic review and network meta-analy…

Cohort2026 · Int J Reprod Biomed

Efficacy and safety of different cetrorelix doses in the luteal phase for preventing ovarian hyperstimulation…

Cohort2021 · BMC Pregnancy and Childbirth

Effects of half-dose and full-dose GnRH antagonists on IVF-ET outcomes: a retrospective study

+3 more

Melanotan II

RCT2000 · Urology

Effect of an alpha-melanocyte stimulating hormone analog on penile erection and sexual desire in men with org…

Review2014 · Expert Opinion on Investigational Drugs

Melanocortin receptor agonists in the treatment of male and female sexual dysfunctions: results from basic re…

About Cetrorelix

Competitive GnRH receptor antagonist; immediately blocks pituitary GnRH receptors; rapidly suppresses LH/FSH without initial flare effect; used for controlled hormonal suppression

Research Areas

HPG axis suppressionLH/FSH reductioncontrolled ovarian stimulation supporttestosterone management

About Melanotan II

Synthetic melanocortin receptor agonist (MC1R-MC5R); activates MC4R for erectile function/libido; MC1R for melanogenesis; MC3R for appetite suppression

Research Areas

central MC4R-mediated sexual arousal and erectile functionskin tanning via MC1R melanogenesis activationappetite suppression (MC4R hypothalamic pathway)significant side effect profile — nausea, flushing, pigmentation (vs cleaner successor PT-141)

Safety Profile

Information below reflects published research data only — not medical advice. Consult a qualified provider before use.

Cetrorelix

Absolute Contraindications

Pregnancy — contraindicatedLactation — contraindicated

Source: FDA label

Suggested Monitoring

Under clinical review

Being verified by our medical team before we display monitoring guidance for this peptide.

Melanotan II

Warnings & Cautions

No FDA approval — investigationalMelanoma / dysplastic nevi — caution (melanocyte stimulation)Cardiovascular effectsPriapism (males)Known hypersensitivity

Class-based (investigational)

Used Together?

Melanotan II

Antihypertensive medications
Research notes that Melanotan II may influence cardiovascular function via melanocortin receptor activation. Combined use with antihypertensive medications may require blood pressure monitoring. Consult your prescriber before combining.

Price (per mg)

Cetrorelix

Not enough vendor pricing yet.

Melanotan II

$4.00/mg

$3.45 – $4.36 range

37 vendors

View price index →Find providers →

Find Providers

Where to source these peptides

Providers offering

Cetrorelix

1 listed

Browse directory →

Providers offering

Melanotan II

94 listed

Browse directory →

PeptideBase lists providers for educational research purposes only. Always consult a qualified healthcare professional before obtaining or using any peptide.

More Reproductive & Hormonal Comparisons

Browse all peptides →

Educational research tools — not medical advice.

Cite this page

Data last updated August 26, 2026

Free to reference and republish with attribution to PeptideBase. Choose a format:

PeptideBase. (2026). Cetrorelix vs Melanotan II — Per-mg Price Comparison. Retrieved September 11, 2026, from https://peptidebase.io/peptides/compare/cetrorelix/melanotan-ii

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