PT-141 is the development name for bremelanotide, a synthetic melanocortin receptor agonist that FDA approved in 2019 as Vyleesi for one narrow use: acquired, generalized hypoactive sexual desire disorder (HSDD) in premenopausal women. Vials sold online as "research" PT-141 are not Vyleesi. They're made outside the approved drug's manufacturing controls, and FDA named PT-141 in four warning letters to peptide sellers in August 2026.
Notice: Research peptides are sold for in-vitro laboratory research only. Research-labeled vials are not the approved drug, not for human or animal consumption, and this page is not medical advice. It contains no dosing or use guidance.
The molecule
Vyleesi's FDA label (revised January 10, 2025) describes bremelanotide acetate as "a synthetic, cyclic heptapeptide." Its sequence is Ac-Nle-cyclo-(Asp-His-D-Phe-Arg-Trp-Lys-OH), with a molecular weight of 1025.2 as the free base.
It's a melanocortin receptor agonist. The label says binding to the MC1R and MC4R receptors is most relevant, and that the mechanism by which it works in HSDD "is unknown." Melanotan II, another melanocortin peptide sold in the research market, is a different compound; FDA plans to review it for compounding before the end of February 2027 (FDA).
Who developed it
Palatin Technologies developed bremelanotide and licensed North American rights to AMAG Pharmaceuticals in 2017 (Palatin, June 2019). FDA's approval letter for NDA 210557, dated June 21, 2019, went to AMAG. On December 20, 2023, Palatin announced the completed sale of Vyleesi to Cosette Pharmaceuticals for up to $171 million, with $12 million paid upfront (Palatin).
What FDA approved in 2019
FDA approved Vyleesi to treat acquired, generalized HSDD in premenopausal women (FDA's June 21, 2019 announcement, as reprinted by BioSpace). The approval rests on two 24-week, randomized, double-blind, placebo-controlled trials in 1,247 premenopausal women.
| Outcome (FDA summary) | Vyleesi | Placebo |
|---|---|---|
| Increase of 1.2 or more in sexual desire score | About 25% | About 17% |
| Decrease of 1 or more in distress score | About 35% | About 31% |
| Number of satisfying sexual events | No difference | No difference |
The label sets clear limits. Vyleesi is "not indicated for the treatment of HSDD in postmenopausal women," and it "is not indicated to enhance sexual performance" (label). It isn't approved for men.
Side effects in the trials
Per the label's adverse reaction table, nausea affected 40.0% of patients on Vyleesi versus 1.3% on placebo, flushing 20.3% versus 0.3%, and headache 11.3% versus 1.9%. FDA's announcement also noted:
- Blood pressure: it rose after administration, usually returning to normal within 12 hours. Vyleesi isn't for people with uncontrolled high blood pressure or known cardiovascular disease.
- Skin and gum darkening: about 1% of patients, and in about half of those it didn't resolve after stopping. People with dark skin were more likely to be affected.
- Drug interaction: it may lower oral naltrexone levels.
Why research PT-141 isn't Vyleesi
The approval covers one product: Vyleesi, made by a specific manufacturer under FDA-reviewed controls, labeled for a defined population. A research vial marked "PT-141" has none of that.
- No approval covers it. FDA's approval doesn't extend to the same molecule sold by someone else.
- FDA has acted on it. FDA's August 24, 2026 warning letters to Tex Peptides, Royal Peptides, NuScience Peptides and Peptide Partners each list PT-141 among products FDA considered unapproved new drugs. The letters quote the sellers' own product descriptions as evidence of intended human use. We cover these vendors in our reviews of Royal Peptides, NuScience Peptides and Peptide Partners.
- Contents depend on the seller. Identity, purity and fill are only as good as the vendor and its lab.
FDA's broader position is in FDA peptide regulation in 2026 and are peptides legal?
Regulatory status (October 2026)
- FDA: bremelanotide is approved only as Vyleesi, for the indication above. It doesn't appear on FDA's Category 2 compounding page (April 22, 2026) or the 503A categories list (May 14, 2026).
- Enforcement: four August 2026 warning letters named PT-141, as above.
- WADA: bremelanotide isn't named on the 2026 Prohibited List (list text). Athletes should still check with their anti-doping organization, since WADA's 2027 explanatory note urges "utmost caution" with peptides.
- DEA: we found no federal scheduling action for bremelanotide.
Research-grade vials: what the market looks like
As of October 21, 2026, 67 vendors in our PT-141 price index had it in stock, with a median of $4.50 per mg. The lowest per-mg listings were 10 mg vials:
| Vendor | Listing | Price | $/mg |
|---|---|---|---|
| Bulk Peptide Supply | PT-141 (Bremelanotide) 10mg | $15.00 | $1.50 |
| Sunrise BioResearch | PT-141 10mg | $25.39 | $2.54 |
| Sports Technology Labs | PT-141 (Bremelanotide) 10mg | $25.99 | $2.60 |
Prices are as listed on vendors' sites on October 21, 2026 and change often. Sports Technology Labs also sells SARMs per its own site, which we flag on its review. We don't have a PT-141 vendor ranking yet; our overall method is in best peptide vendors in the USA.
How to check a PT-141 COA
- Identity by mass spectrometry. The result should match bremelanotide's free-base mass of about 1025 (the label's figure), not just show high HPLC purity (HPLC purity explained).
- Confirm it's not a different melanocortin peptide, such as melanotan II (price page), which some vendors sell alongside it.
- Measured content vs the label (purity vs net content).
- Lot number, test date and a named lab you can verify.
More: how to read a peptide COA and the COA checklist.
Bottom line
PT-141 is bremelanotide, and bremelanotide is a real FDA-approved drug, but only as Vyleesi and only for HSDD in premenopausal women. The approval tells you nothing about a research-labeled vial, which is made and tested outside that system and has drawn FDA warning letters in 2026.
Sources are linked inline and were checked October 21, 2026.