PT-141 (Bremelanotide / Vyleesi)

PT-141 (bremelanotide) is one of the few compounds discussed in this space that is actually an FDA-approved drug, sold as Vyleesi. That approval is narrow, and most of the ways people use PT-141 fall well outside it. The evidence behind the approved use is real and well-run; the evidence behind everything else is not.

What it is

Bremelanotide is a synthetic cyclic peptide that activates melanocortin receptors in the brain, mainly MC4R (with activity at MC1R). Unlike sildenafil (Viagra), which works on blood flow, PT-141 acts centrally on neural pathways involved in sexual desire and arousal. The exact mechanism by which this changes desire is not fully understood. It is given by subcutaneous injection roughly 45 minutes before anticipated sexual activity.

The claims

Marketing and clinic copy promote PT-141 as a libido and arousal booster for both women and men, and as a treatment for erectile dysfunction. Online vendors sell unapproved “research” vials for self-injection. The approved use is much narrower: acquired, generalized hypoactive sexual desire disorder (HSDD) in premenopausal women.

What the evidence actually shows

This is the unusual case where genuine, large human RCTs exist. The Phase 3 RECONNECT program (Studies 301 and 302, roughly 1,200 women in the efficacy analysis) ran two identical 24-week, randomized, double-blind, placebo-controlled trials. Both met their co-primary endpoints: statistically significant gains in a desire score and reductions in desire-related distress versus placebo.

But the effect is small. On the FSFI desire-domain score (which runs from 1.2 to 6.0), the integrated improvement over placebo was about 0.35 points. In the FDA’s responder framing, about 25% of treated women reached a meaningful desire response versus about 17% on placebo. Notably, the number of satisfying sexual events did not improve significantly on the prespecified analysis. So the honest summary for the approved use is “real, but modest” — a true drug effect that helps a minority of women more than placebo does.

That strength does not transfer to other uses. The evidence is thin to nonexistent for everything else. An older intranasal formulation tested in men with erectile dysfunction (Diamond et al.) did produce erectile responses, but that development path was abandoned over blood-pressure concerns; there is no completed Phase 3 program and no approval for men. Use for general libido, male ED, or in postmenopausal women is off-label and largely unstudied in modern controlled trials.

The grade here reflects the approved indication, where the human evidence genuinely is strong. Read it narrowly: strong evidence for a small benefit in one specific group, not evidence that PT-141 broadly “works” for desire or erections in everyone.

Legal and regulatory status

In the United States, Vyleesi (bremelanotide) has been FDA-approved since June 2019 for acquired, generalized HSDD in premenopausal women. Worldwide rights were sold by Palatin Technologies to Cosette Pharmaceuticals in December 2023, and the product remains marketed. The gray-market “research” peptide sold for self-injection is not the approved product and is not quality-controlled.

For athletes: bremelanotide is a melanocortin agonist, and it is not explicitly named on the 2026 WADA Prohibited List (the 2026 changes to the peptide-hormone section S2 added other agents, not melanocortins). It should not be confused with the unapproved tanning peptides melanotan I/II, which are different compounds. Anti-doping status can change and depends on context, so competitors should verify the current status of any product via Global DRO before use.

Safety

Side effects are common and well-documented on the label. Nausea affected about 40% of treated patients (versus roughly 1% on placebo), often with the first dose; about 13% needed anti-nausea medication and about 8% stopped because of it. Flushing, headache, and injection-site reactions were also frequent.

PT-141 transiently raises blood pressure and lowers heart rate after each dose (effects usually resolving within about 12 hours), so it is contraindicated in people with uncontrolled hypertension or known cardiovascular disease, and is not recommended in those at high cardiovascular risk. About 1% of patients on the approved monthly dosing developed focal skin darkening (including face, gums, and breasts); resolution after stopping was not confirmed in all of them, and the risk is higher with daily dosing and in people with darker skin. Rare liver injury has been reported (a single well-documented case in the published literature). Long-term safety beyond the trial periods is not well characterized, and self-dosing unapproved product adds further, unquantified risk.

Bottom line

PT-141 is a legitimate, FDA-approved drug with a small but genuinely proven benefit for one specific condition: low sexual desire in premenopausal women. The broader claims for men, general libido, and erectile dysfunction rest on little or no controlled human evidence, and the side-effect and cardiovascular profile is not trivial. Strong evidence for a narrow, modest effect is not the same as a reason to use it broadly. This is not medical advice.

Evidence grade: Strong human (for the approved premenopausal HSDD indication only; off-label uses are unstudied).

Sources

• FDA approves new treatment for hypoactive sexual desire disorder in premenopausal women (FDA news release, 2019)
• VYLEESI (bremelanotide injection) Prescribing Information, DailyMed
• Simon JA et al. Bremelanotide for the Treatment of Hypoactive Sexual Desire Disorder: Two Randomized Phase 3 Trials (Obstet Gynecol, 2019), PubMed 31599840
• Bremelanotide — LiverTox, NCBI Bookshelf (NBK573221)
• Diamond LE et al. Intranasal PT-141 in healthy males and patients with erectile dysfunction, PubMed 14963471
• Palatin Completes Sale of Vyleesi to Cosette Pharmaceuticals (December 2023)
• WADA’s 2026 Prohibited List is now in force, World Anti-Doping Agency
• Athlete Advisory: What’s New on the 2026 WADA Prohibited List? (USADA)