Doses studied
Melanotan 2 in the Studies: Doses, Routes, and Half-Life
What was administered, to which species, by which route — reported as research facts, not as guidance for anyone to follow.
The short version
This page reports the doses, routes, and timing used in Melanotan 2 studies. It is not a how-to. Melanotan 2 is not approved for human use anywhere, there is no established human dose, and nothing here should be read as a recommendation to use it.
With that said, the research record is specific. The few human studies used very small subcutaneous (under-the-skin) injections, scaled to body weight. Rodent studies used a wider range and several routes, including injections straight into the brain to study appetite. One striking finding is that more is not better: a rat nerve study found a middle dose worked while both lower and higher doses did nothing. No one has ever published a reliable measurement of how long Melanotan 2 stays in the human body. What we have is rat data and figures borrowed from its close cousin. Every number below comes from a named study.
Doses used in the human studies
Human exposure to Melanotan 2 has only ever been studied at small scale. The 1996 pilot Phase I study escalated subcutaneous doses from 0.01 to 0.025–0.03 mg/kg, dosed every other weekday for two weeks, and recommended 0.025 mg/kg/day for future Phase I work [2]. The controlled erectile-dysfunction study used a single subcutaneous dose of 0.025 mg/kg [3].
These are reported strictly as the doses investigators administered in supervised research — they are study-design facts, not dosing recommendations, and Melanotan 2 is not approved for human use [4]. No larger trial has ever established a human dose [4].
Melanotan 2 injections and other routes studied
Subcutaneous injection is the primary route in both research and unsanctioned self-administration [2]. Rodent pharmacology has used additional routes that do not translate to people: intravenous dosing in pharmacokinetic and behavioral studies, and intracerebroventricular or direct intracerebral microinjection to probe appetite and energy circuits — for example, 0.1–1 nmol microinjected into the nucleus accumbens in mouse appetite studies [39].
Dose-response is not always linear. In a rat peripheral-nerve-regeneration study, 20 µg/kg every 48 hours was effective while 2 and 50 µg/kg were not — a bell-shaped curve in which the middle dose worked and the extremes did not. Oral dosing is impractical: bioavailability is very low, so the peptide is not meaningfully absorbed by mouth. Unlicensed nasal sprays appear in self-administration case reports but are not a validated route [11].
Melanotan 2 half-life and stability
There is a persistent question about Melanotan 2 half life, and the honest answer is that no validated human pharmacokinetic half-life has been published for Melanotan 2 itself. A rat intravenous study showed biphasic, rapid multi-compartment plasma clearance, but that is rodent data.
The most-cited figures actually come from the closely related linear analog, Melanotan I (afamelanotide), measured in humans: complete subcutaneous bioavailability relative to intravenous, an absorption-phase half-life of roughly 0.07–0.79 hours, and a beta-phase half-life of roughly 0.8–1.7 hours after subcutaneous dosing, with no detectable levels after oral dosing [14]. In both compounds, the visible effect outlasts the molecule by weeks: pigmentation persists long after the peptide has cleared because melanin synthesis continues downstream [14]. As a lyophilized (freeze-dried) powder, Melanotan 2 is reported as stable when kept cold and dry, with reconstituted solutions typically refrigerated per general peptide-laboratory practice; the cyclic lactam-bridged structure gives it more enzymatic resistance than linear alpha-MSH [1].