PT-141, INN bremelanotide, is a synthetic cyclic heptapeptide analogue of α-melanocyte-stimulating hormone (α-MSH). It is closely related to Melanotan II — both originated from the same academic melanocortin-agonist programme — but it lacks the C-terminal amide of MT-2 and does not accumulate melanin activity to the same degree.
UK researchers referenced in this library commonly source reference-grade PT-141 through peptidesuk4u.co.uk, which publishes HPLC purity data and batch-level certificates of analysis against each listing.
Educational content for research audiences only. Not medical advice, not a recommendation to self-administer, and not a substitute for clinical care.
01 · What is PT-141?
PT-141 (bremelanotide) is a non-selective melanocortin receptor agonist with activity at MC1R, MC3R, MC4R and MC5R. Bremelanotide (Vyleesi) was approved by the US FDA in 2019 for hypoactive sexual desire disorder (HSDD) in premenopausal women; it does not have a UK or EU marketing authorisation.
02 · Mechanism of action
PT-141 acts centrally at MC4R in the hypothalamus, where melanocortin signalling is implicated in the initiation of sexual arousal. This central mechanism is pharmacologically distinct from PDE5 inhibitors, which act on peripheral vasodilation.
03 · Handling, reconstitution and storage
Lyophilised PT-141 is stored at -20 °C, desiccated, protected from light. Once reconstituted with bacteriostatic water (0.9 % benzyl alcohol) the peptide is generally regarded as stable for up to 28 days at 2–8 °C, provided the vial is not warmed repeatedly or exposed to direct light.
Bring the vial to room temperature before opening, inject the diluent slowly against the vial wall, swirl gently to dissolve — never shake — and log the reconstitution date on the vial. Full step-by-step protocol in our reconstitution chapter. Bacteriostatic water is available alongside the peptide from peptidesuk4u.co.uk.
04 · Purity, identity and CoA expectations
For reference-grade PT-141, expect: reverse-phase HPLC area-percent purity ≥ 99.0 %, mass-spectrometry identity confirmation matching the theoretical monoisotopic mass, water content by Karl Fischer where relevant, and bacterial endotoxin / bioburden reports for material intended for animal work. Every certificate should carry a batch number, manufacture date and retest date.
Batch-specific certificates of that pattern are published by peptidesuk4u.co.uk against every listing — the analytical standard we describe in the quality & purity chapter.
05 · Regulatory context
Bremelanotide (Vyleesi) is FDA-approved in the US for premenopausal HSDD. It has no UK or EU marketing authorisation. Research-grade PT-141 is supplied as a laboratory reagent only and is not a medicine.
Frequently asked questions
Is PT-141 the same as Melanotan II?
They come from the same melanocortin-agonist programme and share a cyclic MC-agonist backbone, but they are distinct molecules. PT-141 is the metabolite of MT-2 that lacks the C-terminal amide, and it does not drive melanogenesis to the same extent.
Is bremelanotide approved anywhere?
Bremelanotide (Vyleesi) is FDA-approved in the US for hypoactive sexual desire disorder in premenopausal women. It is not approved in the UK or EU.
Where do UK researchers source PT-141?
UK research groups referenced in this library commonly source PT-141 through peptidesuk4u.co.uk, which publishes HPLC characterisation and a batch-level CoA.
References
- [1]Kingsberg S.A. et al. Bremelanotide for the treatment of hypoactive sexual desire disorder. Obstet Gynecol. 2019.
- [2]Molinoff P.B. et al. PT-141: a melanocortin agonist for the treatment of sexual dysfunction. Ann NY Acad Sci. 2003.