Peps
Same starting point, different paths
Both compounds are synthetic versions of alpha-melanocyte-stimulating hormone, the body's signal for producing pigment. Melanotan I was later developed as afamelanotide. Melanotan II is a smaller ring-shaped molecule that acts on more melanocortin receptors, including ones involved in appetite and sexual function, which helps explain its broader side effects.
Melanotan I: tested and approved for one rare disease
Afamelanotide was tested in randomized trials in erythropoietic protoporphyria (EPP), a rare condition in which sunlight causes severe pain. In two trials published in 2015, people given afamelanotide implants could spend longer in sunlight without pain, and quality-of-life measures improved.
It is approved in the U.S. as Scenesse, an implant placed by trained clinicians for adults with EPP. Its label includes skin-surveillance and pigment-change precautions. The approval covers that implant for that disease, not tanning or research vials.
Melanotan II: a tiny pilot and a safety warning
The main human study of Melanotan II is a 1996 pilot phase 1 trial with very few participants. Pigmentation increased in some of them, and nausea, drowsiness and prolonged unwanted erections were reported.
The FDA lists Melanotan II among bulk substances that may present significant safety risks for compounding and notes serious adverse-event reports. It is not approved for any use. PepsRadar does not list Melanotan II products or link to sellers for it.
Where bremelanotide (PT-141) fits
Bremelanotide, also called PT-141, is a related melanocortin drug developed from the same line of research. It is approved in the U.S. as Vyleesi for a specific sexual-desire disorder in premenopausal women, based on two randomized trials. It is a separate medicine with its own label, not a form of Melanotan II.
Continue with the original research
Study examples are based on selected publication abstracts and the explicitly described source documents. This is not a systematic review or an individualized treatment guide. Editorial scope and methods.