# PT-141 (Bremelanotide): The Research Record, Set in Order > PT-141 (bremelanotide) is a melanocortin receptor agonist approved in 2019 for HSDD in premenopausal women. A composed digest of the trials, the central mechanism, and the tolerability record. Approved in 2019 for one indication in premenopausal women, investigational for everything else. This is a composed reading of what the trials measured, the central mechanism, and the tolerability cost — every clinical figure cited to source. ## In plain English PT-141 is another name for **bremelanotide**, a small lab-made protein (a peptide) that acts on the brain to influence sexual desire. It is the same molecule under two names: PT-141 is the research code, bremelanotide is the official drug name. In 2019 it was approved by the FDA for exactly one use — persistent low sexual desire that causes real distress in premenopausal women, a condition called HSDD (hypoactive sexual desire disorder). Every other use — in men, for erections, in older women — sits outside that approval. It works on brain switches, not on blood flow, and the most common complaint with it is nausea. This page sets the record in order; the details follow below, with citations. ## What the PT-141 record establishes PT-141 is the research designation for bremelanotide, a synthetic cyclic heptapeptide (a seven-amino-acid protein joined in a ring) that activates central melanocortin MC3R and MC4R receptors — brain switches that help govern sexual desire, appetite, and skin pigment [1]. As bremelanotide it received FDA approval in June 2019 (NDA 210557) for acquired, generalized HSDD (hypoactive sexual desire disorder — persistent low sexual desire that causes marked personal distress) in premenopausal women [6]. The approval rests on two identical Phase 3 trials, run under the name RECONNECT, enrolling 1,267 premenopausal women with HSDD. Both met their co-primary endpoints: a 1.75 mg subcutaneous (injected just under the skin) as-needed dose produced a statistically significant rise in measured sexual desire and a reduction in desire-related distress versus placebo over 24 weeks [3]. The effect is real but, by the trials' own numbers, modest — a point [is PT-141 FDA-approved](/research) covers in full, and one independent re-analyses press on hard [9]. The headline finding worth surfacing is the mechanism, not the magnitude. PT-141 acts on the brain's motivation circuitry. A controlled neuroimaging study showed it altered how the brain processed erotic stimuli, with the desire effect measurable for up to 24 hours [5]. That central action is what separates it from blood-flow drugs, and it is where the [PT-141 mechanism of action](/research) story begins. ## PT-141 peptide: what the molecule is The **PT-141 peptide** is a cyclic lactam analogue of alpha-MSH (alpha-melanocyte-stimulating hormone — a natural brain peptide that switches on melanocortin receptors). Its sequence is Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH, with a bridge looping the chain into a closed ring; molecular weight 1,025.2 Da, formula C50H68N14O10, CAS 189691-06-3 [1]. The ring is the point: cyclic peptides resist breakdown better than linear ones, which is part of why this molecule held up well enough in development to reach approval where earlier melanocortin candidates stalled. It is a structural relative of melanotan II, but with the C-terminal amide swapped for a carboxylic acid — a small change that shifts the pharmacology toward the sexual-desire effect rather than tanning. PT-141 and bremelanotide are the same compound: PT-141 is the development code, bremelanotide is the international nonproprietary name (INN), and the approved finished product is bremelanotide injection [6]. ## PT-141 for women: the approved HSDD indication **PT-141 for women** is the only use the approval actually covers. Bremelanotide is indicated for acquired, generalized HSDD in premenopausal women — low desire that was not always present, is not limited to one situation, and causes genuine distress [6]. In the RECONNECT trials the integrated desire score (FSFI-desire — one of the standard questionnaires trials use to score sexual desire) rose by +0.35 versus placebo, and the integrated distress item fell by -0.33, both statistically significant [3]. The effect is not large, and the literature is openly split on what it means clinically [9]. What is settled is the boundary: the approval is for premenopausal women with HSDD and no one else. Postmenopausal women were not in the indication; men were not in the indication. Those distinctions matter, and the [the RECONNECT Phase 3 trials](/research) page treats both the efficacy and the critiques in detail. ## PT-141 as a melanocortin receptor agonist A **melanocortin receptor agonist** is a molecule that switches on the melanocortin receptor family (MC1R through MC5R), the receptors that respond to peptides like alpha-MSH. PT-141 targets the central pair — MC4R chiefly, MC3R secondarily — which sit in hypothalamic and limbic circuits tied to sexual motivation [1]. Animal work mapped the effect cleanly: in female rats the compound selectively increased solicitational (desire-driven) sexual behavior without changing motor activity or reflexive responses, identifying it as the first agent shown to act on appetitive female sexual behavior [2]. The same receptor family explains the compound's other documented effects. MC4R also sits in appetite circuits, which is why high-frequency research dosing reduced food intake and body weight in early studies [7]. Peripheral MC1R activation underlies the skin and gum darkening seen with repeated dosing [6]. One mechanism, several consequences — set out across [PT-141 mechanism of action](/research). ## How this site is organized The record is sorted by what a reader actually wants to find. [PT-141 mechanism of action](/research) covers the central brain mechanism, the RECONNECT endpoints, and the critical re-analyses. [PT-141 dosage in the research](/dosage) reports the label and trial doses as findings, never as a protocol, alongside half-life and timing. [PT-141 side effects](/side-effects) is the tolerability reference: a cited adverse-event layer and a clearly-separated, unverified community-reports layer kept visibly apart. [PT-141 for men](/pt-141-for-men) handles the off-label, investigational male and erectile research honestly. The [common questions about PT-141](/faq) answer the recurring questions, and the [study references](/references) list every citation with its DOI or PubMed link. --- A composed printed monograph that sets the PT-141 (bremelanotide) record in order — the one approved indication, the modest measured endpoints, and the nausea-led tolerability cost arranged and cited, with the unverified field reports kept on their own marked sheet; no clinic behind the press and nothing here prescribed, dispensed, or sold.