PT-141 (Bremelanotide) Research Peptide

What Is PT-141?

PT-141 is a seven-amino-acid peptide modeled on alpha-melanocyte-stimulating hormone (alpha-MSH), the natural hormone that activates the melanocortin receptor family. Unlike the natural linear hormone, PT-141 is cyclic: a lactam bridge joins the side chains of aspartic acid and lysine, closing six of its amino acids into a ring. That ring makes the molecule far more resistant to enzymes and holds it in a shape that fits melanocortin receptors.

PT-141 has an unusually well-documented history for a research peptide. It grew out of Melanotan II, studied at the University of Arizona in the early 1990s for skin pigmentation. Palatin Technologies developed the compound as bremelanotide, and on June 21, 2019, the FDA approved it as Vyleesi for acquired, generalized hypoactive sexual desire disorder in premenopausal women. The research-grade PT-141 sold here is not that drug.

In the lab, PT-141 is used as a well-characterized melanocortin agonist. It activates several receptors in the family, including MC1R, MC3R, MC4R and MC5R. Its activity at MC3R and MC4R, which are concentrated in the brain, is the most studied; MC1R activity is linked to pigmentation. For how it compares with its parent compound, see Melanotan 2 vs PT-141.

This product is strictly for research purposes only. Not approved for human or animal use.

Key Characteristics

Molecular Profile

Physical Properties

PT-141 in Published Research

Because bremelanotide went through a full FDA approval program, PT-141 has far more published human pharmacology than most research peptides. Two Phase 3 trials, known as RECONNECT, formed the basis of the 2019 approval. The approved label reports nausea as the most common adverse reaction and notes transient increases in blood pressure, data that researchers cite when comparing melanocortin agonists.

Earlier human pharmacology work described PT-141’s effects as centrally mediated, acting through receptors in the brain rather than on peripheral blood flow. Preclinical studies, including MC4R knockout mouse models, helped map which melanocortin receptors drive which responses. That makes PT-141 a common reference compound for receptor-selectivity research alongside alpha-MSH and Melanotan II.

Melanotan II itself is now under FDA review: it is one of five peptides due before the FDA’s compounding advisory panel by the end of February 2027. See the FDA’s next peptide review and Melanotan 1 vs Melanotan 2.

Frequently Asked Questions

What is PT-141 used for in research?

PT-141 is used as a reference melanocortin-receptor agonist, especially in studies of MC3R and MC4R signaling and in comparisons with alpha-MSH and Melanotan II.

Is PT-141 the same as bremelanotide?

Yes. PT-141 is the research name for bremelanotide, the active ingredient of the FDA-approved drug Vyleesi. Research-grade PT-141 is not the approved drug and is sold for laboratory use only.

How is PT-141 different from Melanotan II?

They share the same cyclic core. PT-141 ends in a free carboxylic acid, while Melanotan II ends in an amide. Melanotan II has never been approved; PT-141 (as bremelanotide) was approved in 2019.

Which receptors does PT-141 activate?

Several melanocortin receptors, including MC1R, MC3R, MC4R and MC5R. MC3R and MC4R activity is the most studied.

What is included in a PT-141 kit?

Each 10 mg kit contains 10 vials of lyophilized PT-141. Every batch is verified by HPLC and mass spectrometry, and the lot COA is available on request.

How should PT-141 be stored?

Refrigerated at 2–8 °C (36–46 °F), sealed, dry and away from light. For long-term storage, −20 °C. Here’s why freeze-dried peptides ship safely at room temperature.