PT-141 (Bremelanotide)
What PT-141 is
PT-141, also called bremelanotide, is a cyclic heptapeptide analogue of alpha-melanocyte stimulating hormone. It acts at melanocortin receptors, principally MC4R and MC3R.
The distinguishing feature is where it acts. PDE5 inhibitors such as tadalafil and sildenafil work peripherally on vascular smooth muscle and blood flow. PT-141 works centrally, through melanocortin signalling in the nervous system. Those are entirely different mechanisms addressing different aspects of the same broad research area.
At a glance
| Class | Melanocortin receptor agonist |
|---|---|
| Also called | Bremelanotide |
| Structure | Cyclic heptapeptide, alpha-MSH analogue |
| Primary receptors | MC4R, MC3R |
| Reported half-life | Approximately 2 to 3 hours |
| Presentation | Lyophilised powder |
| Storage | 2 to 8 °C |
Relationship to Melanotan II
PT-141 and Melanotan II are closely related, and the history explains the pairing. PT-141 is a metabolite of Melanotan II, and interest in it arose from effects observed during MT2 research that were unrelated to pigmentation.
| PT-141 | Melanotan II | |
|---|---|---|
| Receptor profile | More selective for MC4R/MC3R | Non-selective across melanocortin receptors |
| MC1R activity | Substantially reduced | Present, hence pigmentation effects |
| Half-life | ~2-3 hours | ~30 minutes to 1 hour |
MC1R is the pigmentation receptor. PT-141's reduced activity there is why it is studied separately from the tanning-associated effects that characterise MT2.
Reconstitution and storage
Room temperature before adding diluent. Run the liquid down the inside wall of the vial rather than striking the powder, let it dissolve without agitation, and never shake. The solution should be clear and colourless.
Concentration is total peptide divided by diluent volume, as covered in the concentration guide.
Sealed and dry, store at 2 to 8 °C protected from light. Reconstituted, refrigerate upright and dark and do not freeze. Where bacteriostatic water is used, the 28 day window from first puncture generally governs.
Frequently asked
Is PT-141 the same as Viagra or Cialis? No, and the mechanisms are not comparable. Those are PDE5 inhibitors acting peripherally on blood flow. PT-141 is a peptide acting centrally through melanocortin receptors.
Does it cause tanning like Melanotan II? It has substantially reduced MC1R activity, which is the pigmentation receptor, so it is not studied for that purpose.
Is it a steroid? No. It is a seven amino acid cyclic peptide.
Why is it also called bremelanotide? Bremelanotide is the international non-proprietary name. PT-141 is the development code. Same compound.