Melanotan II · UK research stock

It acts at melanocortin receptors, and research has followed two of their roles: skin pigmentation and sexual function ^[1]. In a pilot phase I study in three men it increased pigmentation of the face, upper body and buttocks, and was accompanied by spontaneous erections, mild nausea and a stretching and yawning response ^[2]. A double-blind, placebo-controlled crossover study in ten men with psychogenic erectile dysfunction reported erections in eight of them ^[4]. In rodents it serves as a tool for central melanocortin signalling: given centrally to mice, it increased whole-body glucose disposal, independent of food intake ^[5].

Human data stop at those small early studies, and clinical development moved to its analogue bremelanotide (PT-141) ^[1]. Its use in the general population was the subject of a BMJ editorial as early as 2009 ^[6]. A Danish case report describes melanoma in a young woman who had combined it with sunbed tanning, and calls the drug unlicensed and incompletely tested ^[7]. The UK's MHRA says it has repeatedly acted over more than ten years to remove melanotan products from sale, and it received 13 suspected adverse reaction reports linked to melanotan II between 2011 and 2021 ^[8].