Melanotan I vs Melanotan II half-life
Melanotan I has an elimination half-life of about 1.2 h; Melanotan II has about 1 h. Melanotan I (afamelanotide) is a linear alpha-MSH analogue approved as an implant for erythropoietic protoporphyria. Melanotan II is a smaller cyclic analogue that also acts on receptors linked to sexual function and appetite.
Side by side
| Melanotan I | Melanotan II | |
|---|---|---|
| Half-life | 1.2 h (range 48 min–1.7 h) | 1 h |
| Route | SC / implant | SC |
| Category | Melanocortins | Melanocortins |
| Evidence | Limited | Limited |
| Remaining after 24 hours | <0.01% | <0.01% |
| Remaining after 7 days | <0.01% | <0.01% |
| ~97% cleared (5 half-lives) | 6 h | 5 h |
| Steady state (4-5 half-lives) | 4.8 h to 6 h | 4 h to 5 h |
Single-dose decay
Share of one dose remaining over time, assuming first-order elimination. Dashed lines mark each half-life.
Melanotan I (t½ 1.2 h) Melanotan II (t½ 1 h)
Melanotan I: Small human SC study: 0.8–1.7 hours. The implant formulation is release-limited. Melanotan II: Rodent data only (about 1 hour); no published human PK.
FAQ
Which lasts longer, Melanotan I or Melanotan II?
Melanotan I lasts longer. Its half-life is about 1.2 h, versus 1 h for Melanotan II, roughly 1.2 times longer.
How long do Melanotan I and Melanotan II stay in your system?
With first-order elimination, about 97% of a single dose is cleared after five half-lives: roughly 6 h for Melanotan I and 5 h for Melanotan II. Individual clearance varies.
How long until Melanotan I and Melanotan II reach steady state?
With consistent repeated dosing, levels approach steady state after 4 to 5 half-lives: about 4.8 h to 6 h for Melanotan I, and 4 h to 5 h for Melanotan II.
How reliable are these half-lives?
Melanotan I: Limited evidence. Melanotan II: Limited evidence. Anecdotal values are community estimates and may be far off.