Melanotan II and PT-141 are the two most-referenced peptides in melanocortin research, and they're closely related — in fact, one is derived from the other. But they're studied through different receptors and different research areas. Here's the clear breakdown.

The quick answer

Melanotan II is a broad, non-selective melanocortin agonist — it acts across multiple melanocortin receptors. PT-141 (bremelanotide) is actually a metabolite of Melanotan II that acts more specifically on the MC4 receptor. So they're family — PT-141 is the more targeted relative.

What each one is

Melanotan II is a synthetic cyclic analogue of alpha-melanocyte-stimulating hormone (α-MSH). Because it's non-selective, it's studied across the melanocortin system broadly — most notably in pigmentation research (the MC1 receptor).

PT-141 is what Melanotan II partly breaks down into in the body. It concentrates its activity on the MC4 receptor in the central nervous system, which is why it's studied in a narrower, different area.

The key difference: different receptors, different research

  • Melanotan II — non-selective across melanocortin receptors; studied heavily in skin pigmentation and tanning research (MC1 pathway).
  • PT-141 — more selective for the MC4 receptor; studied in central sexual-response research in the nervous system.

These describe fields of scientific study — not claims about effects in humans.

Side-by-side

  • Relationship: PT-141 is a metabolite of Melanotan II
  • Selectivity: Melanotan II = broad/non-selective; PT-141 = MC4-focused
  • Main research area: Melanotan II = pigmentation; PT-141 = central sexual-response pathways
  • Handling: both are lyophilised powders — store at −20°C, reconstitute with bacteriostatic water, refrigerate once mixed

Sourcing both in Australia

We hold both Melanotan II and PT-141 in Australian stock, independently batch-tested with published Certificates of Analysis, dispatched same or next business day. See the actual lab results in our CoA Library.

Shop melanocortin research peptides

All products are supplied strictly for laboratory and in-vitro research use only. Not for human or veterinary consumption. This article describes fields of scientific research and is not medical advice or a claim about effects in humans.