PT-141 is the research name for bremelanotide, a melanocortin peptide approved for exactly one use.

The short version

PT-141 is the research-chemical name for bremelanotide, a lab-made peptide (a short chain of amino acids) that switches on certain receptors in the brain tied to sexual desire. The US Food and Drug Administration (FDA) approved bremelanotide in June 2019 for one use only: low sexual desire that causes real personal distress in premenopausal women. Every other use — in men, for erection problems, in postmenopausal women, or for sexual "performance" — is off-label and not backed by that approval. The effect the trials found is statistically real but modest, and the most common side effect is nausea. This page summarizes what the published studies and the drug label actually report. It is not medical advice and recommends no dose for anyone.

What Is PT-141?

PT-141 is the research designation for bremelanotide, a synthetic cyclic heptapeptide — seven amino acids joined in a closed ring — that is a synthetic analogue of alpha-MSH (alpha-melanocyte-stimulating hormone, a natural brain signal that activates a family of receptors called melanocortin receptors) ^[6]. Its molecular weight is 1025.2 Da and its formula is C50H68N14O10 ^[6]. The ring is closed by a lactam bridge between two side chains, which makes it more stable than a straight-chain peptide ^[1].

The distinction that runs through this whole site: bremelanotide is the FDA-approved injectable drug, and PT-141 is the name the same compound carries in the research-chemical context. Material sold as "PT-141 research chemical" is laboratory material — not the approved, quality-controlled finished drug product, and not subject to regulatory oversight of its identity, purity, or concentration ^[11]. The single approved use is the approved HSDD indication in premenopausal women; everything else is research.

One sentence to anchor on: PT-141 acts on the brain's desire circuitry, not on blood flow — which is why it behaves nothing like the erectile-blood-flow drugs it is often confused with ^[1].

PT-141 Peptide: A Synthetic Melanocortin Analogue

The PT-141 peptide is built as a cyclic seven-residue ring: Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH, a synthetic analogue of alpha-MSH with the C-terminal amide replaced by a carboxylic acid ^[6]. It is a structural relative of an earlier melanocortin peptide, but the ring closure and that single chemical swap give it the receptor profile and stability that carried it into clinical development ^[1].

Mechanistically it is a melanocortin (MC3R/MC4R) receptor agonist — a molecule that switches those brain receptors on rather than blocking them ^[1]. In rats and nonhuman primates, systemic PT-141 produced erections and activated hypothalamic neurons (a rise in the activity marker c-Fos), consistent with a central — brain-level — mechanism rather than a peripheral one ^[1]. CAS number 189691-06-3; FDA UNII 6Y24O4F37N; the approved product is NDA 210557 ^[6].

What Is a Melanocortin Receptor Agonist?

A melanocortin receptor agonist is a molecule that activates the melanocortin receptors — a family of five G-protein-coupled receptors (MC1R through MC5R) that normally respond to peptides like alpha-MSH ^[1]. Think of them as a set of brain-and-body switches: MC3R and MC4R sit mainly in the central nervous system and influence sexual desire and appetite, while MC1R sits in the skin and governs pigment ^[6].

PT-141 is an agonist chiefly at the central MC4R, with secondary activity at MC3R ^[1]. That central targeting is the whole story — it is why the compound modulates desire directly, and also why activating the peripheral MC1R switch can darken skin and gums with repeated dosing, one of the cardiovascular and hyperpigmentation signals covered on the tolerability page ^[11].

PT-141 for Women: The Approved HSDD Indication

The single FDA-approved use of bremelanotide is acquired, generalized hypoactive sexual desire disorder (HSDD) in premenopausal women ^[6]. HSDD is persistently low or absent sexual desire that causes marked personal distress and is not better explained by another condition — the distress, not the low desire alone, is the defining feature ^[6].

Approval rested on two identical Phase 3 randomized controlled trials, RECONNECT, in 1,267 premenopausal women with HSDD ^[3]. Bremelanotide 1.75 mg given under the skin (subcutaneously) on an as-needed basis met both coprimary endpoints versus placebo over 24 weeks: an integrated improvement in the desire score of the Female Sexual Function Index (FSFI — a standard sexual-function questionnaire) of +0.35 (P<.001), and a reduction in desire-related distress on the FSDS-DAO scale (item 13) of -0.33 (P<.001) ^[3].

Those effects are statistically significant and they are also clinically modest — a point covered honestly under what the trials measured. The approval covers premenopausal women and no one else.

Approved for one population — investigational everywhere else

It is worth stating the boundary as plainly as the data allow. Bremelanotide is approved for premenopausal women with HSDD ^[6]. It is not approved for men, for erectile dysfunction, for postmenopausal women, or for sexual enhancement or "performance" of any kind ^[6].

There is genuine early-phase research in men — dose-dependent erectile activity in men with erectile dysfunction was reported in 2003-2004, and a Phase 2 combination study began in 2024 ^[1][7][14]. That work is real, and it is also investigational and off-label, summarized on PT-141 for men (off-label research) where it is flagged as not-approved on every claim. The same caution applies to weight and appetite: because MC4R also sits in appetite circuits, caloric-intake effects appeared at high-frequency Phase 1 dosing — a pharmacological observation, not an approved use ^[11].

For the full record, see the frequently asked questions about PT-141 or the full reference list.