Encyclopedia

PT-141 (bremelanotide) is an FDA-approved melanocortin receptor agonist marketed as Vyleesi for acquired, generalized hypoactive sexual desire disorder (HSDD) in premenopausal women. It acts through central (brain) arousal pathways rather than the vascular system, distinguishing it from erectile-dysfunction drugs. It is a subcutaneous injection taken before anticipated sexual activity.

Bremelanotide is a cyclic heptapeptide derived from melanotan II. It was approved by the FDA in June 2019 (Vyleesi) for acquired, generalized HSDD in premenopausal women. It activates melanocortin receptors (notably MC4R) in the central nervous system; the precise mechanism by which it improves sexual desire is not fully established. The approved product is a subcutaneous autoinjector delivering 1.75 mg, used at least 45 minutes before anticipated sexual activity, with no more than one dose per 24 hours and no more than eight per month. It can cause a transient increase in blood pressure and decrease in heart rate, and is associated with focal hyperpigmentation. Although the approved indication is for women, it is also used off-label and sold by research-chemical vendors for other purposes; only the Vyleesi indication is FDA-approved.

Mechanism of Action

Agonist at melanocortin receptors (including MC4R) in the central nervous system, modulating neural pathways involved in sexual desire and arousal. Unlike PDE5 inhibitors, it works centrally rather than through peripheral vascular effects. The exact mechanism for its effect on desire is not fully characterized.