# PT-141 (Bremelanotide): One Approved Use, and Everything Outside It > PT-141 is a melanocortin MC4R agonist, FDA-approved in 2019 for one indication only. A measured digest of what the research establishes and where the approval begins and ends. A measured reading of the bremelanotide record — what the trials and the FDA label establish, exactly where the approval begins and ends, and what the research-chemical form is not. ## The short version PT-141 is the lab name for **bremelanotide**, a small lab-made peptide (a short chain of amino acids) that acts in the brain. It switches on a brain signal called the melanocortin MC4 receptor — a control point the body normally uses to set sexual desire and appetite. Switching it on can raise the feeling of desire. That is different from how erection pills work; those open up blood flow in the body, while PT-141 works in the brain. In 2019 the U.S. Food and Drug Administration (the FDA, the agency that approves medicines) approved one prescription form for one use only: low sexual desire that causes distress in women who have not yet reached menopause [7]. Every other use you may read about — in men, in older women, for performance — has not been approved and is still being studied [10]. A separate version sold online as a "research chemical" is not the approved medicine and is not quality-checked [13]. This site reads that record carefully and tells you which is which. The benefits people report, including the downsides, are on [PT-141 effects](/effects). ## What is PT-141 PT-141 is a synthetic cyclic heptapeptide — a ring of seven amino acids — built as an analogue of **alpha-MSH** (alpha-melanocyte-stimulating hormone, a natural brain signal cut from a larger precursor protein) [1]. Its international nonproprietary name is bremelanotide, and the two names point at the same molecule [10]. It carries the CAS identifier 189691-06-3 and a molecular weight near 1025.2 Da. What sets PT-141 apart from most peptides discussed online is that it has a genuine, dated regulatory record. The FDA approved bremelanotide injection on June 21, 2019, under NDA 210557 [7]. That approval is narrow: it covers acquired, generalized hypoactive sexual desire disorder (HSDD — persistent, distressing low desire) in premenopausal women, at 1.75 mg given under the skin as needed [10]. The peptide also has a parallel life as an unapproved "research chemical," and the distance between those two existences is the load-bearing fact of this whole page. ## PT-141 peptide: a central mechanism, not a vascular one The PT-141 peptide works in the brain. It activates central melanocortin receptors — chiefly MC4R, with some MC3R activity — that are concentrated in the hypothalamus and limbic system [1]. By stimulating MC4R in circuits such as the medial preoptic area (a hypothalamic region tied to sexual motivation), it is thought to engage dopamine pathways that govern desire [5]. This is a different mechanism from PDE-5 inhibitors, the well-known erection drugs, which act peripherally on blood-vessel smooth muscle. A controlled in-vitro study makes the contrast concrete: alpha-MSH relaxed rabbit vaginal-wall and artery tissue, while bremelanotide at 1 µM did not — consistent with a central, not a peripheral vascular, action [12]. PT-141 does not act through the testosterone (HPG) axis and does not directly raise testosterone; that is a common misconception worth clearing early. The full mechanism is on the [melanocortin receptor agonist](/how-it-works) page. ## What the human trial record actually shows The strongest human evidence comes from two identical Phase 3 trials known together as RECONNECT (n=1267 premenopausal women with HSDD) [3]. Bremelanotide 1.75 mg as needed produced a statistically significant improvement in sexual desire (integrated FSFI-desire +0.35, P<.001) and reduced desire-related distress (FSDS-DAO item 13 −0.33, P<.001) versus placebo over 24 weeks [3]. A 52-week open-label extension (684 women) showed sustained benefit and no new safety signals [4]. Those are real, replicated findings — and they are modest. Independent re-analyses argue the effect sizes, while significant, are small, and they question how clinically meaningful the chosen outcome measures are [the controversies are catalogued on /effects]. Both things are true at once, and a careful reading holds them together rather than picking one. The benefits people actually report, with the downsides, live on [PT-141 effects](/effects); the cited evidence is on [PT-141 research](/research). ## Where the approval begins and ends This is the boundary the site is built around. The approval covers **premenopausal women with HSDD** — and nothing else [10]. Use in men, in postmenopausal women, for erectile dysfunction, or for "performance" is off-label or investigational, even though early Phase 2 erectile-dysfunction data exist [1]. The peptide also falls under WADA's non-approved-substances framework (S0) in contexts without current therapeutic approval; athletes should consult current WADA guidance directly. The "PT-141 research chemical" sold online sits entirely outside the pharmaceutical framework — no regulatory oversight of identity, purity, or concentration [13]. The label also carries hard limits: a warning on transient blood-pressure increases and a contraindication in uncontrolled hypertension or known cardiovascular disease [7]. None of this is presented here as guidance for any individual. It is the record, read straight, with every approval limit marked rather than blurred. --- A spectrometer-style readout of the PT-141 (bremelanotide) record — every value logged to its source and marked in-spec or contested, the lone 2019 approval for premenopausal HSDD calibrated against every off-label and research-chemical use that sits outside its band; no clinic behind the instrument and nothing here prescribed, dosed, or sold.