What is PT-141?
PT-141, also known as bremelanotide, is a synthetic cyclic heptapeptide. It is an analog of alpha-melanocyte-stimulating hormone (α-MSH). Its sequence is N-acetyl-Nle-Asp-His-D-Phe-Arg-Trp-Lys. A lactam bond between Asp and Lys closes it into a ring. It ends in a free carboxylic acid (PubChem CID 9941379). It was created as an analog of melanotan II (Hadley and Dorr, 2006).
It is an agonist at melanocortin receptors, including MC3R and MC4R. These receptors are expressed mainly in the central nervous system (Molinoff et al., 2003). Published PT-141 peptide research covers receptor structure, plus rodent and primate behavior. It also covers clinical pharmacology and analytical chemistry.
A bremelanotide drug product, Vyleesi, was approved by the US FDA in 2019. The approval is for premenopausal women with acquired, generalized hypoactive sexual desire disorder (Dhillon and Keam, 2019). The PT-141 that Disguised Alpha sells is a research-grade lyophilized peptide for laboratory use. It is not that drug product. It is not intended for that indication or any clinical use, and it is not for use in people.
PT-141 reference data
| Property | Value |
|---|---|
| Name | PT-141 |
| Aliases | Bremelanotide, PT 141 (PubChem CID 9941379) |
| Sequence | N-acetyl-L-norleucyl-L-α-aspartyl-L-histidyl-D-phenylalanyl-L-arginyl-L-tryptophyl-L-lysine (2-7)-lactam, free C-terminal acid (PubChem CID 9941379) |
| Peptide class | Cyclic heptapeptide |
| Molecular formula | C₅₀H₆₈N₁₄O₁₀ |
| Molecular weight | 1025.18 g/mol |
| CAS number | 189691-06-3 |
| Form | Lyophilized powder |
| Size carried | 10MG |
| Testing | Third-party tested, with the certificate for each lot published on the product page and in the COA portal |
Formula, molecular weight, CAS number and peptide class come from the Compound Information section of the PT-141 product page. The 10 mg size is the labeled amount shown there. Sequence and aliases come from PubChem (CID 9941379, which lists 1025.2 g/mol). Check identity and measured content against your lot's certificate.
What the research covers
Published work on PT-141 falls into six areas. Each summary below states the model used. Human studies used drug products in clinical settings. They describe those products, not the research material sold here.
Receptor pharmacology and structure
A team solved high-resolution structures of full-length MC4R in complex with its G protein. Peptide agonists in these structures were α-MSH, afamelanotide and bremelanotide. A structure with a small-molecule agonist was solved as well. With pharmacological assays, they showed a conserved binding mode for the peptide agonists (Zhang et al., 2021). A neurobiology review notes that PT-141 activates several melanocortin receptor subtypes nonselectively. It also sums up animal work on where it acts.
That work suggests it acts on presynaptic MC4R in the medial preoptic area of the hypothalamus. The suggested effect is a rise in dopamine release (Pfaus et al., 2022). In human glioblastoma cell lines, the peptide reduced survivin expression. It also caused cell death at concentrations not toxic to normal human cells. An MC3R and MC4R antagonist blocked both effects (Suzuki et al., 2024).
Rodent and primate models
In rats and nonhuman primates, PT-141 produced penile erections. In rats given it systemically, c-Fos immunoreactivity rose in the hypothalamus. This protein is a marker of neuron activation (Molinoff et al., 2003). In female rats, it selectively increased solicitation behaviors. It did not change lordosis or pacing. It did not cause generalized motor activation. Nor did it alter measures of sexual reward (Pfaus et al., 2004).
Early clinical pharmacology
Early human studies included healthy men and men with erectile dysfunction. In both groups, PT-141 produced a rapid increase in erectile activity (Molinoff et al., 2003). A crossover study enrolled 18 premenopausal women with sexual arousal disorder. It compared PT-141, given once by the nasal route, with placebo. More women reported moderate or high sexual desire after PT-141.
Vaginal vasocongestion did not differ significantly (Diamond et al., 2006). Two phase 1 trials studied premenopausal women with obesity. They were set up to study MC4R effects on appetite. They reported lower calorie intake, by roughly 400 kcal per day in one trial. They also reported greater short-term weight reduction than placebo (Spana et al., 2022).
Phase 3 trials and reanalysis
Two identical 24-week phase 3 trials included 1,267 premenopausal women with hypoactive sexual desire disorder. The women were randomized to the drug product or placebo. The trials reported statistically significant differences in the coprimary desire and distress scores. Nausea, flushing and headache were more common than with placebo (Kingsberg et al., 2019). An independent reanalysis argued that most protocol-listed outcomes went unreported. It also argued that discontinuation due to adverse events was much higher with bremelanotide (Spielmans, 2021).
Safety and cardiovascular measurements
A study of 397 premenopausal women used ambulatory monitoring. It found small, transient rises in systolic blood pressure of 2.4 to 3.2 mmHg relative to placebo. These came during the first 4 hours. Peaks usually lasted under 15 minutes. Heart rate fell in the highest-exposure group (White et al., 2017). Pooled safety data span a clinical program of 43 studies and about 3,500 participants.
In the phase 3 double-blind period, the most common adverse events were nausea, flushing and headache. Nausea rates were 40.0 percent, versus 1.3 percent with placebo. Some participants received it daily for up to 16 days in a row. More than a third of them had focal hyperpigmentation (Clayton et al., 2022).
Analytical chemistry and stability
A validated UHPLC-MS/MS assay measured the peptide in 100 µL of plasma, down to 10 pg/mL. It was used to study oral exposure in beagle dogs (Sauter et al., 2020). Forced-degradation work used international guideline stress conditions. It found bremelanotide acetate more stable under acidic than basic conditions. It was also highly prone to oxidation. Heat and light caused further breakdown. Eight degradation products were found. They were traced to deacetylation, peptide-bond hydrolysis, oxidation and epimerization (Yuvaraaj and Sharma, 2026).
Key studies
- Molinoff PB, et al. "PT-141: a melanocortin agonist for the treatment of sexual dysfunction." Ann N Y Acad Sci. 2003. PMID 12851303. DOI 10.1111/j.1749-6632.2003.tb03167.x. Rats, nonhuman primates and early human studies: receptor activity, c-Fos and erectile responses.
- Pfaus JG, et al. "Selective facilitation of sexual solicitation in the female rat by a melanocortin receptor agonist." Proc Natl Acad Sci U S A. 2004. PMID 15226502. DOI 10.1073/pnas.0400491101. Female rats: solicitation, lordosis, pacing and motor activity.
- Diamond LE, et al. "An effect on the subjective sexual response in premenopausal women with sexual arousal disorder by bremelanotide (PT-141), a melanocortin receptor agonist." J Sex Med. 2006. PMID 16839319. DOI 10.1111/j.1743-6109.2006.00268.x. Placebo-controlled crossover study in 18 premenopausal women.
- White WB, et al. "Usefulness of ambulatory blood pressure monitoring to assess the melanocortin receptor agonist bremelanotide." J Hypertens. 2017. PMID 27977473. DOI 10.1097/HJH.0000000000001221. Randomized trial in 397 women: ambulatory blood pressure and heart rate.
- Dhillon S, Keam SJ. "Bremelanotide: First Approval." Drugs. 2019. PMID 31429064. DOI 10.1007/s40265-019-01187-w. Review of the development program milestones.
- Kingsberg SA, et al. "Bremelanotide for the Treatment of Hypoactive Sexual Desire Disorder: Two Randomized Phase 3 Trials." Obstet Gynecol. 2019. PMID 31599840. DOI 10.1097/AOG.0000000000003500. Two phase 3 randomized trials, 1,267 premenopausal women, 24 weeks.
- Sauter M, et al. "Ultra-sensitive quantification of the therapeutic cyclic peptide bremelanotide utilizing UHPLC-MS/MS for evaluation of its oral plasma pharmacokinetics." J Pharm Biomed Anal. 2020. PMID 32353679. DOI 10.1016/j.jpba.2020.113276. Bioanalytical method validation in plasma, beagle dogs.
- Zhang H, et al. "Structural insights into ligand recognition and activation of the melanocortin-4 receptor." Cell Res. 2021. PMID 34433901. DOI 10.1038/s41422-021-00552-3. Structural biology: MC4R-G protein complexes with peptide and small-molecule agonists.
- Clayton AH, et al. "Safety Profile of Bremelanotide Across the Clinical Development Program." J Womens Health (Larchmt). 2022. PMID 35147466. DOI 10.1089/jwh.2021.0191. Pooled safety data from 43 clinical studies.
Handling and storage of lyophilized PT-141
General lab practice for this material:
- Store the powder at -20°C, away from light, until use. Storage guidance is on the product page.
- Let the sealed vial reach room temperature before opening. This keeps moisture from condensing on the powder.
- In forced-degradation work, oxidation was a major cause of breakdown. Heat and light also caused breakdown. The peptide was less stable under basic than acidic conditions (Yuvaraaj and Sharma, 2026). Keep oxidizers and alkaline solutions away, and protect solutions from light.
- Breakdown can include epimerization, which may not change mass. For older solutions, a stability-indicating chromatographic method tells you more than mass alone.
- Once the powder is dissolved, keep solutions at 2 to 8°C and away from light. Split stock into single-use aliquots to avoid freeze/thaw cycles.
- Record the lot number and keep its certificate with your notes. For quantitative work, use the measured content on the certificate, not the label mass.
Frequently asked questions
What is PT-141?
PT-141 is a cyclic heptapeptide analog of α-MSH (PubChem CID 9941379). It is a melanocortin receptor agonist (Molinoff et al., 2003). It is studied in receptor structure work, rodent and primate behavior and clinical pharmacology.
Is PT-141 the same as bremelanotide?
Yes. PubChem lists PT-141 and bremelanotide as names for the same compound (CID 9941379). Bremelanotide is the international nonproprietary name. The PT 141 peptide sold here is research material, not the drug product.
How does PT-141 differ from melanotan II?
They share the cyclic Ac-Nle-Asp-His-D-Phe-Arg-Trp-Lys core. Melanotan II ends in a C-terminal amide (C₅₀H₆₉N₁₅O₉, 1024.18 g/mol). PT-141 ends in a free acid (C₅₀H₆₈N₁₄O₁₀, 1025.18 g/mol). These figures come from both product pages and PubChem (CIDs 92432 and 9941379). See our melanotan II research guide.
Which receptors does PT-141 act on?
It is an agonist at MC3R and MC4R (Molinoff et al., 2003). It has been resolved in a structure bound to MC4R (Zhang et al., 2021). It also activates several melanocortin receptor subtypes nonselectively (Pfaus et al., 2022).
How should PT-141 powder be stored?
Keep the lyophilized powder at -20°C and away from light. Once dissolved, store the solution at 2 to 8°C, away from light. Avoid freeze/thaw cycles. These steps are listed on the product page.
Where can researchers buy PT-141?
Disguised Alpha sells it for laboratory research. It is third-party tested, with the certificate published on the product page: PT-141 (10MG).
Related compounds and guides
- Melanotan 2, the parent cyclic analog, and its research guide
- Melanotan 1 and its research guide
- COA portal: every published certificate, by lot
This product is for research use only. It has not been evaluated for safety or effectiveness in humans. Not for human consumption. All products are intended for laboratory research purposes only.