Melanocortin
research.

Melanocortin-receptor agonists are studied in pigmentation, appetite and sexual-function research. Melanotan I (afamelanotide) is a linear alpha-MSH analogue with selectivity for MC1R and is approved under the name Scenesse for erythropoietic protoporphyria. Melanotan II is a cyclic, non-selective analogue that served as the basis for PT-141 (bremelanotide), an MC4R-focused compound approved in the US for a specific indication.

The category illustrates how small structural changes shift receptor selectivity, which makes these compounds useful tools for receptor pharmacology.