# PT-141 (Bremelanotide): What the Trials and the Label Actually Establish > PT-141 is the research name for bremelanotide, a melanocortin MC3R/MC4R receptor agonist FDA-approved in 2019 for HSDD in premenopausal women. The cited record, read gauge by gauge. A cited digest of the molecule, the RECONNECT trials, the FDA label, and the honest adverse-event record — with the tolerability gauges read before the prose. ## 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](/how-it-works); for the documented adverse events, see [PT-141 side effects](/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](/research) covers the RECONNECT trials, the FDA approval scope, and the honest efficacy picture. [PT-141 side effects](/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](/dosage) reports only the trial and label doses as findings, never as a protocol. The [common questions about PT-141](/faq) answer the 22 most-asked questions, and the [full reference list](/references) holds every citation with its DOI or PubMed link. --- A gauge-by-gauge read-out of the published PT-141 (bremelanotide) record — each cited figure sealed under glass with its source, the lone approved indication and the nausea-led tolerability cost lit first, and the unverified field reports pinned off to one side and stamped as such; no clinic behind the panel and nothing here dosed, dispensed, or sold.