PT-141 (Bremelanotide)
A synthetic melanocortin agonist approved as bremelanotide for hypoactive sexual desire disorder; also studied for arousal and sexual behavior.
Overview
PT-141, known generically as bremelanotide, is a synthetic cyclic peptide agonist of melanocortin receptors, principally MC3R and MC4R. It was developed from earlier melanocortin research peptides and is approved in the United States (as Vyleesi) for hypoactive sexual desire disorder in premenopausal women. In peptide-research contexts it is studied for its effects on sexual behavior and arousal.
Mechanism
Bremelanotide activates central melanocortin pathways implicated in sexual arousal and reward, an action independent of the gonadal hormone axis. Relative to earlier analogs, it was designed to reduce activity at the melanocortin-1 receptor responsible for skin pigmentation, although the approved product still carries a skin-darkening warning.
Dosing
As an approved drug it is administered by subcutaneous injection per its label. In research contexts it is handled as a lyophilized peptide for receptor and behavioral studies; all non-approved use should be treated as research dosing.
- Approved label use is a single subcutaneous injection taken before anticipated sexual activity
- Onset of action in the approved setting is typically within roughly an hour
- Research protocols in animal models use route- and species-specific doses
Expected Effects
- Increased sexual desire and arousal in premenopausal women with hypoactive sexual desire disorder in registration studies
- Effects on sexual motivation in rodent models
- Dose-limiting tolerability, mainly nausea, in clinical use
Side Effects & Tolerability
Nausea is the most common adverse effect and a frequent reason for discontinuation; flushing, headache, and injection-site reactions also occur. Blood pressure may transiently increase, and the drug is contraindicated in uncontrolled hypertension and cardiovascular disease per its label. Melanocortin pharmacology can rarely cause darkening of skin and other tissues.
Storage
Lyophilized peptide should be stored cold and protected from light and moisture. Reconstituted solutions should be used promptly or aliquoted and refrigerated, avoiding repeated freeze-thaw cycles.