The story

The same Arizona laboratory that hardened alpha-MSH into Melanotan I went a step further and closed the molecule into a ring, which produced a smaller, tougher, far less selective compound. In 1998 Hunter Wessells and colleagues published something nobody was looking for: given to ten men with erectile difficulty of no physical cause, it produced clear erections in eight of them with no sexual stimulation present, with firm rigidity lasting an average of 38 minutes against 3 minutes on placebo. They repeated it in twenty men including those with physical causes, where seventeen of twenty responded and two thirds reported increased desire. That finding launched an entire class of centrally acting arousal medicines and led directly to bremelanotide. Meanwhile the molecule escaped into bodybuilding and tanning culture, bought as powder online, and European dermatology began reporting what followed: darkening moles, new irregular moles, a cluster of melanoma reports, one case of rhabdomyolysis, several of priapism. Irish dermatologists catalogued 623 forum discussions from 205 users to understand how people were actually using it. Chemical analysis of products sold online found what they contained did not reliably match what they claimed. Russian work took it in a different direction entirely, testing it beside Semax as an antidepressant and antistress peptide in rats.