Peptide Reference Desk
Melanotan II, afamelanotide and bremelanotide: the family resemblance stops at the label
A clear map of three melanocortin-related peptides that search results often merge despite different structures, receptor profiles and regulatory records.
Why the names get tangled
Melanotan II, afamelanotide and bremelanotide share a development history around melanocortin pharmacology. That family connection has produced years of loose naming online. It has not produced three interchangeable molecules.
Afamelanotide is a linear α-MSH analogue associated with an approved implant in a defined regulatory context. Melanotan II is a distinct cyclic peptide widely discussed in unapproved tanning markets. Bremelanotide—also known by the development label PT-141—is another related cyclic melanocortin agonist with its own approved-drug record.
A quick way to keep the files straight
| Name | Structural cue | Archive warning |
|---|---|---|
| Afamelanotide | Linear α-MSH analogue | Do not call every “Melanotan I” product an approved implant. |
| Melanotan II | Cyclic melanocortin analogue | Do not transfer an approved relative’s status to it. |
| Bremelanotide / PT-141 | Related cyclic melanocortin agonist | Keep approved formulation records separate from research material. |
Receptor activity is not a safety shortcut
All three names lead into melanocortin-receptor literature, but their receptor profiles, formulations, exposures and evidence packages differ. “Same family” does not mean same selectivity, indication or adverse-effect record. It also does not make unregulated Melanotan II a substitute for sunscreen or an approved medicine.
How to audit a research listing
Require the complete sequence and cyclization description where applicable, expected and observed mass, salt form, HPLC method, content and lot traceability. If a listing uses MT-I, MT-II and PT-141 language in the same description, treat that as a reason to ask more questions—not as evidence of versatility.
Search the molecule you mean
Use the exact generic name plus the document type: “afamelanotide FDA label,” “Melanotan II receptor pharmacology,” or “bremelanotide randomized trial.” That small change keeps approved-drug evidence from drifting onto a different peptide.
Check the primary record
Use a primary paper, regulator document or lot-linked analytical file for the claim it actually supports. Record the access date for time-sensitive status information.