Melanotan II

Research-Grade

Melanotan II (MT-II) is a cyclic heptapeptide analog of α-melanocyte-stimulating hormone, binding non-selectively across MC1R through MC5R. It was developed in the 1980s at the University of Arizona in search of a photoprotective tanning agent, but was never commercialized because of the hypertension and nausea profile of non-selective MC agonism. Its legacy persists because of two derived drugs: PT-141 (bremelanotide, FDA-approved Vyleesi) and afamelanotide (Scenesse, FDA-approved for erythropoietic protoporphyria). MT-II itself is a research peptide, used off-label for tanning and reported libido effects. The principal MC1R-driven effect is melanogenesis; MC4R/MC3R drive the other observed effects. Spontaneous erections, transient hypertension, and nausea are common dose-dependent adverse events. Atypical mole darkening and new-onset pigmented lesions have been reported — any melanocytic change requires dermatologic assessment, particularly because MT-II users often pursue tanning goals that increase UV exposure simultaneously.