Comparison
Cetrorelix vs. Melanotan II
Two peptides side-by-side — identity, evidence base, legal status and known adverse events.
Identity
Category
Research other
Research other
CAS no.
120287-85-6
121062-08-6
Molecular weight
1431.06 g/mol
1024.18 g/mol
Half-life
no data
1 h
Sequence
no data
Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2Mechanism of action
Cetrorelix
Cetrorelix competitively and immediately blocks the pituitary GnRH receptor, rapidly suppressing LH and FSH release — without the initial hormone surge ('flare') of GnRH agonists.
Melanotan II
Melanotan II binds non-selectively to all five melanocortin-receptor subtypes (MC1R-MC5R). Via MC1R in melanocytes, eumelanin synthesis is stimulated (pigmenting effect). Via MC4R and MC3R in the CNS, appetite, sexual function and blood pressure are modulated. The cyclic structure and D-amino acids increase stability compared to natural α-MSH.
Evidence base
Highest evidence
Human RCT
Human trial
Studies
0
9
of which in humans
0
5
Effects recorded
2
4
Open conflicts
0
1
Documented adverse events
1
6
Legal status
Full entries
Frequently asked questions
- What is the difference between Cetrorelix and Melanotan II?
- Cetrorelix is classified as "Research other", while Melanotan II is classified as "Research other". Cetrorelix: Cetrorelix is a synthetic decapeptide and GnRH antagonist. It is used in assisted reproduction (IVF) to prevent a premature LH surge during controlled ovarian stimulation. Melanotan II: Cyclic hepta-peptide and non-selective melanocortin-receptor agonist. Originally researched at the University of Arizona as a sun-protection concept — never approved as a medicine. Widespread on the black market; regulatory warnings for cardiovascular and oncological risks. This page contrasts both neutrally and source-based — with no usage or dosing recommendation.
- Which peptide is better supported by science, Cetrorelix or Melanotan II?
- The highest available evidence level is "Human RCT" for Cetrorelix and "Human trial" for Melanotan II. A higher evidence level means more robust data, but says nothing about suitability for an individual. The full body of evidence is on each peptide's own page.
- What is the legal status of Cetrorelix and Melanotan II in Germany and the United States?
- Germany: Cetrorelix — Prescription, Melanotan II — Unapproved. United States: Cetrorelix — Prescription, Melanotan II — Unapproved. These are factual summaries with source and review date on the individual pages.