Melanotan II
What Melanotan II is
Melanotan II is a synthetic cyclic analogue of alpha-melanocyte stimulating hormone. Unlike PT-141, which was developed from it, MT2 is non-selective across the melanocortin receptors, and that lack of selectivity defines its profile.
It binds at MC1R, the receptor governing melanin production in melanocytes, which is the basis of the pigmentation research it is known for. It also binds at MC3R and MC4R, which is where the overlap with PT-141 originates.
At a glance
| Class | Melanocortin receptor agonist |
|---|---|
| Structure | Cyclic alpha-MSH analogue |
| Receptor profile | Non-selective (MC1R, MC3R, MC4R) |
| Reported half-life | Around 30 minutes to 1 hour |
| Presentation | Lyophilised powder, or nasal spray |
| Storage | 2 to 8 °C, protect from light |
Melanotan I and Melanotan II
Two distinct compounds sold under confusingly similar names.
| Melanotan I | Melanotan II | |
|---|---|---|
| Also called | Afamelanotide | MT2 |
| Structure | Linear | Cyclic |
| Selectivity | More MC1R-selective | Non-selective |
The names imply a version relationship that does not exist. They are different molecules with different receptor profiles, and results from one do not transfer to the other.
Nasal spray against injection
MT2 is supplied here both as a lyophilised vial and as a nasal spray. These are not equivalent presentations and the difference matters more than it does for most compounds.
Nasal absorption of peptides is variable, depending on mucosal condition, technique and formulation. A vial reconstituted to a known concentration gives you a measurable quantity; a nasal spray gives you a measured volume delivered, with absorption a separate and less controlled question.
The spray arrives ready to use. Refrigerate once opened and observe the supplier's stated in-use period.
Reconstitution and storage
Room temperature before adding diluent. Run the liquid down the inside wall of the vial, let it dissolve unaided, never shake. Clear and colourless when correct.
Light protection matters here. Store sealed vials at 2 to 8 °C in the dark, and do not leave a reconstituted vial standing on a lit worktop. Refrigerate upright, and never freeze a solution.
Frequently asked
Is MT2 the same as PT-141? No, though they are related. PT-141 is a metabolite of MT2 with substantially reduced MC1R activity, so it lacks the pigmentation profile.
Is Melanotan I the earlier version of Melanotan II? No. They are structurally different molecules, linear against cyclic, with different receptor selectivity.
Is it a steroid? No. It is a cyclic peptide analogue of a naturally occurring hormone fragment.
Vial or nasal spray? The vial gives a known concentration and measurable quantity. The spray delivers a measured volume with less predictable absorption. They are not interchangeable on a quantity basis.