PT-141 (Bremelanotide) | 20mg | 3ml

PT-141, also called bremelanotide and written PT141 or PT 141, is a synthetic cyclic heptapeptide melanocortin-receptor agonist. Structurally it is a close relative of Melanotan 2: the same seven-residue, lactam-bridged scaffold, differing at a single position on the C-terminus — and that one change is what gives it a distinct receptor-selectivity profile. Ours is supplied pre-mixed as a solution in a sealed 3 ml vial, 20mg per vial, HPLC-verified with a batch Certificate of Analysis, synthesised and dispatched from our UK facility.

Research use only. PT-141 is supplied strictly for in-vitro laboratory research. This page describes chemistry, format, quality and handling. It does not describe dosing, administration or use in humans or animals, and makes no therapeutic claims.

PT-141 at a glance

What PT-141 is, chemically

Seven residues, one of them acetylated at the N-terminus, and a lactam bridge closing Asp to Lys into a ring. Two of the residues are non-standard on purpose: norleucine (Nle) in place of methionine, and D-phenylalanine rather than the L isomer. Both substitutions, together with the cyclisation, make the molecule far more resistant to enzymatic degradation than a linear peptide of the same length — which is precisely what a reference compound needs to be, since a reagent that degrades during an assay is not measuring what the experiment thinks it is.

The C-terminus is a free acid (-OH). That single detail is the whole difference between this compound and its parent scaffold, and it is covered in the next section.

PT-141 vs Melanotan 2: one atom's worth of difference

The two share an identical cyclic scaffold and differ only at the C-terminal group:

Replacing the terminal amide with a hydroxyl changes the molecular mass by about one unit and the receptor-selectivity profile substantially. That is the reason the pair is used comparatively so often: they are as close to a controlled single-variable comparison as two distinct research compounds get, which makes them a standard way to attribute an observation to MC4R rather than to melanocortin signalling in general. We supply both, with matching documentation.

How PT-141 is studied

In biochemical and cell-based systems PT-141 is used as an MC3R/MC4R agonist, with comparatively higher potency at MC4R and substantially reduced activity at MC1R relative to the broad-spectrum scaffold. That selectivity makes it a tool for isolating MC4R-mediated signalling: G-protein-coupled cAMP accumulation, phospholipase-C cascades, intracellular calcium flux and ERK/MAPK activation in receptor-expressing and neuronal cell models. It also appears in structure–activity relationship work on cyclic α-MSH analogues, where the amide-versus-acid comparison above is the variable under study. Responses reported in these systems vary with receptor subtype, concentration, exposure time and model; they are laboratory observations only, and are not established effects in humans or animals. The PT-141 guide covers the literature in more depth.

PT-141, PT141, PT 141, bremelanotide: one compound

The naming is messier than it needs to be, and it costs buyers time when comparing listings. Bremelanotide is the international non-proprietary name — the systematic, assigned name for the molecule. PT-141 is the development code that stuck, and it is what research suppliers almost universally catalogue it under; PT141 and PT 141 are the same code written without the hyphen. All four refer to one compound with one CAS number, 189691-06-3, and one formula. If two listings quote different CAS numbers or different masses for "PT-141", one of them is describing something else.

Worth separating from that list: PT-142 and other numbered variants that occasionally appear are distinct compounds, not spellings of this one.

Pre-mixed PT-141 vs lyophilised

Most UK listings for PT-141 are lyophilised powders that have to be reconstituted with bacteriostatic water. Ours is supplied already in solution: no reconstitution step, no bacteriostatic water to source separately, and the concentration shown in the key facts above holds for every vial in the batch. A solution must stay cold — vials ship chilled in an insulated pouch, go into a 2–8 °C refrigerator on arrival, and should be used within the storage window on the label rather than held as shelf stock.

Quality: HPLC purity and the Certificate of Analysis

Every PT-141 batch is verified by HPLC at 99%+ purity, and the figure on the Certificate of Analysis is the value recorded for that batch rather than a generic claim. A batch-specific COA ships with every order, and sample certificates are viewable in the COA library before you buy. Because PT-141 and the MT-II scaffold differ by about one mass unit, the certificate is also the only practical way to confirm which of the two is in a vial — a point worth pressing with any supplier who cannot produce one.

Storage and handling

• Refrigerate at 2–8 °C on arrival; keep the vial sealed and protected from light.
• Do not freeze. Freeze–thaw cycling damages peptides already in solution.
• Draw from the vial with standard aseptic laboratory technique.
• Check the certificate for the recorded appearance and the storage window for that lot.

Buying PT-141 in the UK: what to check

1. Which scaffold. PT-141 and MT-II differ by roughly one mass unit; only a certificate reporting the measured mass distinguishes them.
2. Mass per vial and, for a solution, the concentration.
3. A batch-specific Certificate of Analysis naming the batch, the method and the appearance, viewable before you order.
4. Format. Powder needs bacteriostatic water and a reconstitution step; a pre-mixed solution needs cold-chain delivery and a refrigerator.
5. Legal status. PT-141 is not a licensed medicine in the United Kingdom. It is supplied here strictly as a laboratory reference compound for in-vitro research, labelled for that use, and is not supplied for human or veterinary use.