PT-141

PT-141, or bremelanotide, is the C-terminal deaminated metabolite of Melanotan II — the same cyclic scaffold with a free carboxyl in place of the terminal amide. That single change measurably shifts receptor preference toward MC4R and away from MC1R, which is why it produces markedly less pigmentation activity than its parent while retaining central melanocortin effects. The research literature focuses on MC4R-mediated central signalling.

Because it is chemically so close to Melanotan II, the two are genuinely easy to confuse and the mass difference is small. Anyone stocking both needs the chromatography to separate them, and anyone stocking only one still needs it to prove they have the one they claim. We run both against a qualified standard on the same gradient so the retention time comparison is meaningful.