RESEARCH INDEX // MC4R AGONIST // BREMELANOTIDE
PT-141 acts on melanocortin receptors in the brain — not blood vessels. Here is what the studies measured.
Central agonist. One approved use. Modest, real effect. Nausea-led tolerability. Every number below maps to a citation.
The short version
PT-141 is a lab name for bremelanotide, a small synthetic peptide. It copies a natural brain signal called alpha-MSH. Most drugs for sexual problems work on blood flow. PT-141 does not. It works in the brain — on switches called melanocortin receptors (MC4R and MC3R) that help set sexual desire.
One use is FDA-approved: treating low sexual desire that causes distress (a condition called HSDD) in women who have not gone through menopause. Every other use — in men, after menopause, or for "performance" — is off-label or still experimental, not approved.
The approved effect is real but small. The main downside is nausea, which is common. A material sold as a "PT-141 research chemical" is a lab reagent, not the approved medicine, and no one checks its purity. What people report — including the downsides — is on PT-141 effects. This page recommends no dose for anyone.
What the PT-141 literature has demonstrated
PT-141 is a synthetic cyclic heptapeptide — a ring of seven amino acids — that activates central melanocortin receptors, chiefly MC4R (a brain switch involved in both sexual desire and appetite) [1]. It is a structural analogue of alpha-MSH, an endogenous neuropeptide [1].
The defining finding is mechanistic. In rats, nonhuman primates, and men with erectile dysfunction, systemic PT-141 produced dose-dependent erectile activity and lit up hypothalamic neurons (measured as increased c-Fos), evidence of a central, not vascular, action [1]. In female rats it selectively raised solicitational (desire-driven) sexual behavior without changing reflexive behavior or motor activity [2].
In women, two identical Phase 3 trials (RECONNECT, n=1267) tested bremelanotide 1.75 mg subcutaneous as-needed against placebo over 24 weeks. Both coprimary endpoints were met: desire rose (FSFI-desire +0.35, P<.001) and desire-related distress fell (FSDS-DAO item 13 -0.33, P<.001) [3].
The full mechanism, the comparison to other agents, and the open questions are on PT-141 research.
Central agonist, not a vascular drug
The comparison is the whole story. PDE-5 inhibitors act peripherally on vascular smooth muscle to improve erectile blood flow [13]. PT-141 acts centrally, on hypothalamic circuitry governing sexual motivation [1][13]. Central vs. peripheral. Desire vs. blood flow. Brain vs. plumbing.
This matters for what PT-141 can and cannot do. It does not act through the HPG axis and does not directly raise testosterone — a common misconception [7]. A 2022 fMRI study in 31 women with HSDD showed MC4R agonism altered task-based brain processing of erotic stimuli (enhanced amygdala-insula connectivity), increasing desire for up to 24 hours [5]. The signal is neural.
Reviews place bremelanotide among centrally acting agents for sexual dysfunction, distinct from vascular options [13]. The PT-141 benefits page details what that central action has measured.
What this site is
This is a research index, not a vendor. It summarizes the published bremelanotide literature and the US prescribing information [7]. It does not sell PT-141, recommend a dose, or provide medical advice.
The entries below are sorted by source. Approved-label facts are flagged as such. Off-label and research-chemical claims are flagged as such. Unverified community reports are kept separate from cited evidence — see PT-141 effects. The full citation list, with DOIs and PubMed links, is on PT-141 references.