PT-141 (Bremelanotide)

Vyleesi

PT-141 (bremelanotide) is a synthetic analog of α-melanocyte-stimulating hormone (α-MSH) that acts as a non-selective agonist at melanocortin receptors, with MC4R thought to mediate the sexual-function effect. It evolved from Melanotan II after hypertension concerns required engineering out the vascular component. FDA-approved as Vyleesi in 2019 for premenopausal women with hypoactive sexual desire disorder (HSDD), it is also studied and used off-label in men for erectile dysfunction — particularly cases unresponsive to PDE5 inhibitors, since it works centrally rather than via vasodilation. Self-administration is subcutaneous, typically 1.75 mg at least 45 minutes before anticipated activity, with doses limited to 8 per month per label. Unlike PDE5 inhibitors, PT-141's mechanism is pharmacologically central, not peripheral. Adverse events are dominated by nausea (approximately 40% of users in trials), flushing, and transient blood-pressure increases; prolonged exposure to high doses can produce facial hyperpigmentation because of MC1R agonism.