PT-141 is the research name for bremelanotide, a melanocortin receptor agonist with one approved use and a tolerability cost worth reading first.

The short version

PT-141 is the research name for bremelanotide, an injectable peptide that the FDA approved in 2019 for one thing: low sexual desire that causes real personal distress in premenopausal women — a diagnosis called HSDD (hypoactive sexual desire disorder). It works in the brain, not on blood flow, by switching on melanocortin receptors (MC3R/MC4R — brain switches tied to sexual desire, appetite, and skin pigment). In the approved group the benefit is real but modest, and the main trade-off is nausea. Every number on this page comes from a published trial or the FDA label, and you can check each one. This is a digest of that record, not medical advice.

What the PT-141 literature actually establishes

PT-141 (bremelanotide) acts on the brain. By switching on central melanocortin receptors — chiefly MC4R, with secondary MC3R — in hypothalamic and limbic circuits, it engages dopamine pathways tied to sexual motivation rather than acting on the blood vessels ^[1]. That single mechanistic fact separates it from every PDE-5 inhibitor (drugs like sildenafil and tadalafil that work peripherally on vascular smooth muscle to improve erectile blood flow).

The approval is narrow and worth stating plainly. Bremelanotide injection is FDA-approved (NDA 210557, June 21, 2019) only for acquired, generalized HSDD in premenopausal women ^[6]. It is not approved for men, for postmenopausal women, for erectile dysfunction, or to enhance sexual performance. Use outside that one indication is off-label, and material sold as 'PT-141 research chemical' sits entirely outside the approval, with no regulatory oversight of identity, purity, or concentration.

The evidence base behind that approval is substantial. Two identical Phase 3 randomized trials (the RECONNECT program, 1,267 premenopausal women with HSDD) found 1.75 mg subcutaneous (injected just under the skin) as-needed produced a statistically significant improvement in sexual desire versus placebo over 24 weeks ^[3]. A 52-week open-label extension sustained that effect with no new safety signals ^[4]. A mechanistic fMRI study in 31 women showed MC4R agonism altered how the brain processed erotic stimuli ^[5]. The honest framing is that the benefit is real, the mechanism is central, and the tolerability — led by nausea — is the part you read first.

PT-141 peptide: what the molecule is

The PT-141 peptide is a synthetic cyclic heptapeptide — seven amino acids joined in a ring — that mimics alpha-MSH (alpha-melanocyte-stimulating hormone), one of the body's own melanocortin signals. Its sequence is Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH, with a lactam bridge closing the ring; that cyclic structure makes it more stable than a linear peptide ^[1].

By the numbers: molecular weight 1025.2 Da, formula C50H68N14O10, CAS 189691-06-3, FDA UNII 6Y24O4F37N. It is the same molecule as the approved drug bremelanotide — 'PT-141' is the development designation, 'bremelanotide' is the international nonproprietary name (INN). It is a structural relative of melanotan II, but with the C-terminal amide replaced by a carboxylic acid, which shifts its activity toward the central MC3R/MC4R targets that matter for sexual desire ^[1].

For the full mechanism, see how PT-141 works; for the documented adverse events, see PT-141 side effects.

PT-141 for men: the off-label, investigational picture

PT-141 for men is off-label and, at best, investigational. The earliest human work — dose-ranging intranasal studies in men with erectile dysfunction — found a rapid, dose-dependent erectile response, with a statistically significant effect above roughly 7 mg ^[1]. That signal is mechanistically interesting: it is consistent with a central melanocortin action rather than a peripheral one. But it is early-phase, the intranasal route was later discontinued for pharmacokinetic variability, and a separate 2008 erectile-dysfunction salvage study now carries a 2023 Expression of Concern, so its findings should be treated as disputed.

What does not follow is any approved male use. There is no FDA approval for men, no large confirmatory efficacy trial in the male/erectile setting, and no labeled dose for it. A 2021 review of emerging erectile-dysfunction therapies discusses melanocortin agonists like bremelanotide as a centrally acting class still under investigation ^[11]. The honest read: a real early signal, no established benefit, and no approval. PT-141 does not act through the hypothalamic-pituitary-gonadal axis and does not directly raise testosterone — a common misconception the mechanism corrects.

Read the record by section

This site reads the PT-141 record as a set of sealed read-outs, each carried back to its source. The clinical research covers the RECONNECT trials, the FDA approval scope, and the honest efficacy picture. PT-141 side effects carries the documented adverse-event profile — nausea, flushing, headache, the transient blood-pressure rise, and hyperpigmentation — plus a clearly separated, unverified field-reports layer. PT-141 dosage in the research reports only the trial and label doses as findings, never as a protocol. The common questions about PT-141 answer the 22 most-asked questions, and the full reference list holds every citation with its DOI or PubMed link.