PT-141 (Bremelanotide) Research Guide 2026: Melanocortin Pharmacology, Handling & Purity

RESEARCH

Published September 6, 2026

PT-141 (Bremelanotide) Research Guide 2026: Melanocortin Pharmacology, Handling & Purity

Compliance notice: PT-141 (bremelanotide) is supplied strictly For Research Use Only — not for human consumption, not for veterinary use, not intended to diagnose, treat, cure, or prevent any disease. Nothing below is medical advice, and no dosing guidance is given or implied.

PT-141 (bremelanotide) is one of the more frequently mischaracterized compounds in the research-peptide catalog. It is a synthetic cyclic heptapeptide acting as a melanocortin receptor agonist, with a public CAS registry entry. This guide covers what it is chemically, why the melanocortin family is studied, and the handling and purity questions that decide whether a research lot is usable.

Table of Contents

What PT-141 (Bremelanotide) Is

The Melanocortin Receptor Family

Regulatory Status and the RUO Line

Reconstitution, Storage & Handling

What to Verify on the COA

Research FAQ

What PT-141 (Bremelanotide) Is

Bremelanotide is a synthetic cyclic heptapeptide with the sequence Ac-Nle-c[Asp-His-D-Phe-Arg-Trp-Lys]-OH. Its published identifiers are:

CAS number: 189691-06-3

Molecular formula: C50H68N14O10

Molecular weight: approximately 1025.2 g/mol

Two structural details matter. First, it is cyclic — the ring closure between the aspartic acid and lysine residues defines the molecule, so degradation that opens the ring yields a different compound, not a weaker one. Second, it contains a D-phenylalanine residue. That stereochemistry is deliberate, and an analytical method has to resolve it, because the L-isomer is a plausible synthesis byproduct a coarse assay can miss.

The literature describes bremelanotide as an active metabolite of melanotan II, which is why the two are discussed together. They are not interchangeable — melanotan II is a different starting material with a different profile.

The Melanocortin Receptor Family

The melanocortin system comprises five G-protein-coupled receptors, MC1R through MC5R, spanning skin, adrenal tissue, and the central nervous system. Published pharmacology characterizes bremelanotide as an agonist at MC1R, MC3R, and MC4R, with activation coupling to increased cAMP signaling.

That receptor breadth is why the compound is studied at all. A ligand engaging several receptors in the same family is a poor tool for attributing an observation to any single receptor, so melanocortin study designs generally need selective comparators or antagonist controls. Researchers in this area typically keep a related-compound panel — melanocortin ligands such as melanotan I, or adjacent neuroendocrine tools like kisspeptin — so cross-reactivity can be reasoned about rather than assumed away.

Regulatory Status and the RUO Line

This is the part most vendor pages skip, and it matters most. Bremelanotide received FDA approval in June 2019 as a prescription pharmaceutical product, for a specific indication in a specific patient population.

That approved medicine is not what is sold here, and its existence does not make research-grade material a substitute for it. A research lot is released against research specifications — not pharmaceutical GMP, no prescribing label, no clinical oversight. The two share a molecule and nothing else that matters. Any use outside a controlled laboratory setting falls outside what this product is supplied for. Our research use policy states the terms, and we would rather lose a sale than blur that line.

Reconstitution, Storage & Handling

Lyophilized PT-141 ships as a dry powder and is reasonably stable in that state under refrigeration, protected from light. The vulnerable window opens at reconstitution.

Standard practice for this class: reconstitute with bacteriostatic water rather than plain sterile water when the vial will be drawn from more than once, since the benzyl alcohol preservative is what makes repeat access defensible. Direct the stream down the vial wall, not onto the powder cake, and swirl rather than shake — shear and foaming are avoidable causes of degradation, and with a cyclic peptide you cannot see the difference between degraded and intact material. Store reconstituted solution refrigerated, out of light, and avoid freeze-thaw cycling.

The diluent distinction trips people up often enough that we covered it in bacteriostatic water vs sterile water, with the mechanics step by step in our reconstitution guide.

What to Verify on the COA

A certificate of analysis is only worth something if it is tied to the vial in front of you. Check four things:

Lot match. The lot on the COA must match the vial label. An unlotted "representative" COA documents nothing about your material.

HPLC purity. Look for the chromatogram, not just a stated percentage — one large adjacent peak and diffuse noise imply different failure modes.

Mass spectrometry. Observed mass should match the expected weight near 1025.2 g/mol. This catches a wrong or partially cyclized peptide.

Test date. A COA predating your lot is not evidence about your lot.

Our COA reading guide walks through real chromatograms; every lot we release is documented on our lab testing page.

Research FAQ

What is the CAS number for PT-141 (bremelanotide)?

189691-06-3. The molecular formula is C50H68N14O10 and the molecular weight is approximately 1025.2 g/mol.

Is PT-141 the same as melanotan II?

No. They are distinct compounds with distinct structures, though bremelanotide is described in the literature as an active metabolite of melanotan II. They should not be treated as interchangeable in a protocol.

Which receptors does bremelanotide act on?

It is characterized as a melanocortin agonist at MC1R, MC3R, and MC4R, coupling to cAMP signaling. Because it is not receptor-selective, study designs generally require selective comparators or antagonist controls.

How should PT-141 be stored?

Lyophilized powder refrigerated and protected from light. After reconstitution, keep it refrigerated, shield it from light, and avoid freeze-thaw cycling. Do not shake the vial.

Bremelanotide is an approved drug — can research material be used the same way?

No. Research-grade material is released against research specifications, not pharmaceutical GMP, and carries no prescribing label or clinical oversight. It is supplied For Research Use Only and is not for human consumption.

Sourcing PT-141 for Research

What separates a usable lot from an unusable one is documentation you can check: a lot-matched COA, a real HPLC trace, a mass confirmation, a recent test date.

Precision Labs supplies PT-141 (bremelanotide) 10mg with lot-matched third-party analysis. If you want documentation reviewed before ordering, or have a specification question for a particular protocol, contact our team — we will send the current lot's COA before you buy.

For Research Use Only. Not for human consumption. Not for veterinary use. Not intended to diagnose, treat, cure, or prevent any disease.