PT-141 (Bremelanotide, Vyleesi)

PT-141, now marketed as bremelanotide (brand name Vyleesi), is a melanocortin-4 receptor agonist. It was FDA-approved in June 2019 for acquired, generalized hypoactive sexual desire disorder (HSDD) in premenopausal women, based on the two RECONNECT phase 3 RCTs totaling approximately 1,267 women.

The efficacy in HSDD is real but modest. In the RECONNECT trials, approximately 37% of bremelanotide-treated patients reported a clinically meaningful improvement in desire versus approximately 28% on placebo, a difference of about 9 percentage points.

Off-label use in male erectile dysfunction rests on data from an abandoned development program. Approximately 54.5% of men reported improved erectile function at 1.75 mg subcutaneous dose in the historical program, but the program was discontinued in favor of the HSDD indication.

Documented constraints include transient blood-pressure rises, nausea (approximately 40% incidence), and hyperpigmentation. The FDA label warns about cardiovascular risk in patients with uncontrolled hypertension or known cardiovascular disease.

Bremelanotide is administered as a subcutaneous autoinjector 45 minutes before anticipated sexual activity, with no more than one dose per day and no more than eight doses per month. It is a prescription drug, not a research chemical.

The 'PT-141' designation persists in the peptide community where the drug is sometimes sold by research chemical vendors, bypassing the prescription-only status. This carries the same purity and contamination risks as other gray-market peptide products.