What is PT-141?

01

What is PT-141 made of?

The structure of PT-141 is Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH: an acetylated norleucine followed by a six-residue ring closed between aspartic acid and lysine. The reference record lists the formula C50H68N14O10 and a molecular weight of 1025.2 g/mol (PubChem CID 9941379).

It contains two residues outside the standard twenty, norleucine and D-phenylalanine, so the identity result on the COA is the reliable check.

Sources: [1] PubChem · reference structure

02

Where to buy PT-141

PT-141 is sold direct by Prism Labs at prismlabs.store, in 10mg vials at $44.99 per vial. The latest published lab report, tested October 26, 2026, measured 99.82% purity. Every lot’s certificate of analysis is on the product page, with a link to verify it with the testing lab.

Orders placed before 4:30 PM CT ship the same day, seven days a week, when the size is in stock. Standard shipping is free over $125. Packs of 2 or more vials are discounted, up to 18% off.

See PT-141 sizes, prices and lab reports · How to vet any peptide supplier

03

Where did PT-141 come from?

PT-141 was developed by Palatin Technologies as a new analogue of the cyclic Melanotan II (MT-2). Melanocortins are peptide hormones, α-MSH among them, and researchers had already designed long-acting linear and cyclic analogues of them.

The two differ at one end of the chain. Melanotan II (MT-2) ends in an amide (–NH2); PT-141 ends in a free acid (–OH), which is why its formula has one more oxygen and one fewer nitrogen.

For the parent compound’s structure, its 1989 design and the receptors it acts on, see What is Melanotan II (MT-2)?

Sources: [3] Peptides · 2006 · [4] Drugs · 2019 · [2] PubChem · reference structure · [1] PubChem · reference structure

04

What has PT-141 been studied for?

The literature on PT-141 centers on melanocortin receptors:

• It activates several melanocortin receptor subtypes; reviews identify MC4R as the most relevant.
• MC4R is concentrated in the hypothalamus, and much of the research maps its role in brain pathways of sexual response.
• Clinical development under the name bremelanotide, summarized in a 2019 profile.

These are observations in laboratory models. They are not evidence about any use in people.

Sources: [5] CNS Spectrums · 2022 · [4] Drugs · 2019

05

How is PT-141 supplied and stored?

PT-141 ships as a lyophilized (freeze-dried) powder in 10 mg vials. The powder is stable at room temperature in transit. For lab use it is reconstituted with bacteriostatic water such as Prism H2O.

Concentration is content divided by volume: 10 mg in 2 mL gives 5 mg per mL. The reconstitution calculator handles other combinations.

For storage before and after reconstitution, see how to store lyophilized peptides.

06

How do I verify PT-141 batches?

Every lot has its own certificate of analysis from an independent lab. Read three results separately:

• Identity: confirms the expected compound was detected.
• Purity: the share of the measured material that is the intended compound.
• Content: the amount measured, compared with the label.

Then match the lot number on your vial or bottle to the report, and use the report’s verification link to confirm it with the testing lab. Step by step: how to read a peptide COA.