A research digest, read like a score
PT-141 is a central melanocortin agonist measured for desire, not blood flow.
Bremelanotide enters the brain's own desire circuitry rather than the body's plumbing. We score the literature the way it actually reads: a real approved drug, a single approved use, a modest measured effect, and a tolerability passage that gets loud where it counts — every cited figure carried back to its study.
The short version
PT-141 is the research name for bremelanotide, a small lab-made peptide (a short chain of amino acids). It is a real, FDA-approved prescription medicine — but the approval covers exactly one use: low sexual desire that causes real personal distress, in women before menopause. Everything else — men, erectile problems, women after menopause, "performance" — is off-label and still experimental. It works on the brain's desire wiring, not on blood flow, which makes it different from the usual pills. The measured benefit is real but small, and the most common cost is nausea.
What the PT-141 record actually plays
PT-141 (bremelanotide) is a synthetic cyclic heptapeptide — a ring of seven amino acids — that switches on melanocortin MC3R/MC4R receptors (brain switches that influence sexual desire, appetite, and skin pigment) [1]. It is the research designation for the approved drug bremelanotide, and the two names mean the same molecule [6].
The headline finding is regulatory and narrow: bremelanotide injection was FDA-approved in June 2019 (NDA 210557) for acquired, generalized HSDD (hypoactive sexual desire disorder — persistent low sexual desire that causes real personal distress) in premenopausal women [3][6]. In the two pivotal Phase 3 trials, the studied dose was 1.75 mg subcutaneous (injected just under the skin), taken as needed [3].
That single approved use is the whole of what is established. Every other application — PT-141 for men, erectile dysfunction, postmenopausal women, sexual "enhancement" — is off-label and rests on early-phase or investigational evidence only [7][1]. This site reads the published record straight: the central MC4R mechanism, the approved indication, the honestly modest effect, and the PT-141 side effects the trials and the label document.
PT-141 Peptide: The Research Designation for Bremelanotide
"PT-141 peptide" and "bremelanotide" name one compound from two angles: PT-141 is the developmental research label; bremelanotide is the international nonproprietary name (INN) for the approved drug [6]. Structurally it is a synthetic analogue of alpha-MSH (alpha-melanocyte-stimulating hormone — the body's own melanocortin signal), built as a cyclic seven-amino-acid ring closed by a lactam bridge [1]. The molecular weight is 1025.2 Da and the CAS number is 189691-06-3.
The cyclic structure is the engineering point: closing the peptide into a ring makes it sturdier than a straight-chain melanocortin peptide, which is part of why a once-as-needed injection is workable [1]. Materially, the approved finished product is a pre-formulated single-dose subcutaneous injection — not a powder to mix. Anything sold as "PT-141 research chemical" sits outside that approval, is for laboratory research only, and is not the approved drug [3].
What the brain-signal mechanism changes
PT-141 acts centrally, not peripherally. It stimulates MC4R in hypothalamic circuits such as the medial preoptic area (a brain region for sexual motivation), engaging dopamine pathways tied to desire [1][5]. That is a different lane from PDE-5 inhibitors (drugs like sildenafil that work on blood vessels to support an erection): those act on plumbing; PT-141 acts on signal [5].
The cleanest human read of that signal is an fMRI study: in 31 premenopausal women with HSDD, MC4R agonism increased sexual desire for up to 24 hours and changed how the brain processed erotic stimuli — enhanced amygdala-insula connectivity, altered cerebellar and supplementary-motor activity [5]. The drug is a signal entering a circuit, and the imaging is a readout of the circuit responding. For the full account, see how PT-141 works.
The honest dynamics: a modest benefit, a real cost
The measured benefit in the approved population is statistically real and clinically modest. Across the two RECONNECT Phase 3 trials (n=1267), integrated FSFI-desire (the standard desire-domain questionnaire score) improved +0.35 versus placebo, and distress about low desire (FSDS-DAO item 13) improved -0.33 — both P<.001, both small [3]. Independent re-analyses argue the effect is smaller still in clinical terms [8].
The tolerability passage is where the score gets loud. In the 52-week extension, nausea reached 40.4% and was the leading reason participants stopped, with flushing 20.6% and headache 12.0% [4]. The label also warns of a transient blood-pressure rise with a drop in heart rate — contraindicated in uncontrolled hypertension or known cardiovascular disease — and notes focal skin and gum hyperpigmentation with repeated dosing [6]. Read the full blood-pressure and hyperpigmentation cautions before anything else.
For the 1.75 mg label dose, the approved-indication and effect size, and common questions about PT-141, follow the score through.