PT-141 (Bremelanotide): Melanocortin Receptor Research Guide
By UK Peptide Lab Research Team•17 May 2026•6 min read
What is PT-141?
PT-141, also known as Bremelanotide, is a synthetic cyclic heptapeptide derived from the structure of Melanotan II. It was developed by Palatin Technologies through structural modification of Melanotan II to remove the C-terminal amide responsible for MC1R binding while preserving activity at the central melanocortin receptors MC3R and MC4R. The result is a peptide with substantially reduced melanogenic effect and concentrated activity at the central nervous system melanocortin receptors involved in sexual desire and arousal signalling.
MC3R and MC4R Mechanism
PT-141 acts as an agonist at MC4R and, to a lesser extent, MC3R. MC4R is expressed densely in the paraventricular nucleus of the hypothalamus and other central nervous system regions involved in energy homeostasis, sexual behaviour, and inflammation modulation. MC4R activation by PT-141 in research models produces effects on sexual arousal pathways through a central mechanism distinct from the peripheral vascular mechanism of PDE5 inhibitors. The MC4R pathway is downstream of dopaminergic signalling and is thought to act on desire and arousal initiation rather than on erectile vascular response.
Comparison with Melanotan II
PT-141 and Melanotan II share a common structural origin but differ in their pharmacology. Melanotan II activates MC1R, MC3R, MC4R, and MC5R with significant pigmentation effects. PT-141 removes the MC1R activity and concentrates at the central receptors. Research models that require central melanocortin activation without confounding melanogenic effects typically select PT-141 over Melanotan II for that reason. See the Melanotan I vs Melanotan II comparison for additional context on the melanocortin receptor family.
Research Background
Bremelanotide has received clinical approval in the United States for the treatment of hypoactive sexual desire disorder in pre-menopausal women, under the brand name Vyleesi. This clinical approval applies in the United States and is not extended to the UK. Bremelanotide is not approved for human use in the UK by the MHRA. UK Peptide Lab supplies PT-141 as a research-grade peptide for in-vitro laboratory use only.
Laboratory Handling
PT-141 is supplied as lyophilised powder. Store at -20°C prior to reconstitution. Reconstitute with bacteriostatic water by slowly injecting the diluent down the side of the vial and swirling gently. Never shake. Store reconstituted solutions at 2-8°C and use within 4 weeks. Avoid repeated freeze-thaw cycles.
Sourcing in the UK
UK Peptide Lab supplies research-grade PT-141 10mg with full third-party Certificate of Analysis on every product page. Same-day UK dispatch on orders placed before 2pm GMT, free Royal Mail Tracked shipping over £45. For in-vitro laboratory research use only, not for human consumption.
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Disclaimer: This article is for research and educational purposes only. All information provided is not intended as medical advice. UK Peptide Lab products are not for human consumption and are sold strictly for laboratory research use only.