Melanotan II: Non-Selective Melanocortin Agonist
Synthetic cyclic analogue of α-MSH developed as a UV-free tanning agent and precursor to PT-141. Never approved; widely sold illicitly.
👥 Human studies
- Full name
- Melanotan II (MT-II)
- Class
- Non-selective MC1R/MC3R/MC4R agonist (cyclic heptapeptide)
- Half-life
- ~1 hour
- Route
- Subcutaneous (illicit); also intranasal
- Developer
- University of Arizona (academic) → partial clinical programmes
- Regulatory status
- No approval anywhere; multiple national health warnings
What it is
Melanotan II was developed at the University of Arizona in the 1980s as a potential UV-free tanning agent. Because it is a non-selective melanocortin agonist, it activates MC1R (pigmentation), MC3R/MC4R (appetite, arousal), with off-target effects. PT-141 is a selective derivative.
How it works
MC1R agonism on melanocytes stimulates eumelanin production, producing tanning even without UV exposure. Effects persist for weeks after dosing stops.
MC3R/MC4R activation in the central nervous system causes nausea, reduced appetite, spontaneous erections in men, and flushing — off-target effects that limit tolerability and contributed to its non-approval.
What the research shows
Academic pharmacodynamic studies and multiple case reports of illicit use.
Dorr RT et al. (1996) — Phase 1/2 in healthy volunteers
Dorr R.T. et al., Life Sci 1996;58:1777–1784. 👥 Human studies
Healthy volunteers received subcutaneous MT-II with concomitant UV.
Melanin density increased and tanning was achieved with lower UV doses; nausea and flushing were dose-limiting.
Limitations: Off-target effects substantial; programme not continued commercially.
Langan EA et al. (2010) — case-series and atypical naevi
Langan E.A. et al., BMJ 2009;338:b577 (case series). 👥 Human studies
Multiple case reports of new or changing naevi, atypical dysplastic lesions, and rare melanoma in users of illicit MT-II.
Dermatology bodies in the UK, Australia and Europe have issued public warnings.
Limitations: Causality not definitively established; case-based evidence.
Safety and limitations
Common: nausea (severe with initial doses), spontaneous erections, flushing, darkening of moles, focal hyperpigmentation, and lip/gingival darkening. Rare: reports of rhabdomyolysis, kidney injury, and changing naevi.
Illicit preparations sold online have unpredictable purity. Multiple national drug agencies have issued warnings.