PT-141 (bremelanotide)

Also called bremelanotide, bremelanotide acetate, Vyleesi¹

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PT-141 is bremelanotide, a lab-made ring-shaped peptide that switches on melanocortin receptors in the brain. FDA approved it in 2019, as the Vyleesi autoinjector, for premenopausal women with low sexual desire that causes distress.^{1, 2} In two 24-week trials of 1,267 women, desire rose and distress fell a little more than on placebo, but the number of satisfying sexual events did not differ.^{1, 4} About 4 in 10 women had nausea.¹ It is a close chemical relative of the unapproved tanning peptide melanotan II.^{10, 22} It is not approved for men, and "PT-141" vials sold for research are not the approved drug.^{1, 16}

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At a glance

Where to get it

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Molecular structure

Six amino acids closed into a ring, with a seventh, norleucine, hanging off and capped with an acetyl group. The ring is shut by a bond between the side chains of aspartic acid and lysine.

The end acid group. Melanotan II has an amide here instead

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AcNlenorleucineDAspHHisfD-PheRArgWTrpKLys

Sequence

Ac-Nle-cyclo(Asp-His-D-Phe-Arg-Trp-Lys)-OH

Length

7 amino acids, 6 in the ring

Formula

C50H68N14O10

Weight

1,025.2 g/mol

Salt

Acetate

Form

1.75 mg in 0.3 mL, single-dose autoinjector

Sequence, formula, weight and salt from the Vyleesi label, for the free base.¹ Drawn from that sequence; the formula we computed matches the label. Swapping the end acid for an amide gives melanotan II's formula, C50H69N15O9.

What it is

Melanocortins are hormones, such as α-MSH, that act on a family of receptors involved in skin color, appetite and sexual behavior. Bremelanotide is a synthetic analog of α-MSH, built as a small ring.^{1, 8}

Its story starts with melanotan II, a tanning peptide made at the University of Arizona. In a 1996 pilot study of three men, melanotan II caused spontaneous erections.²² Palatin Technologies then developed PT-141, which melanotan II's inventors describe as an analog of it.¹⁰ The two differ at one end: bremelanotide ends in an acid group, where melanotan II ends in an amide.^{1, 22} See our melanotan II guide.

Palatin first tested a nasal spray, in men and women. In 2007 FDA raised questions about blood pressure spikes, and in 2008 Palatin dropped that program.⁹ It came back as an injection under the skin for women. AMAG Pharmaceuticals won approval on June 21, 2019, and FDA called it "another treatment option" for the condition.^{2, 21} AMAG handed the rights back to Palatin in 2020,²³ and in December 2023 Palatin sold Vyleesi to Cosette Pharmaceuticals.¹¹

Palatin also licensed it to partners for China and South Korea.¹¹ We found no approval in Europe or the UK.

How it works

• Melanocortin receptors. It switches on several melanocortin receptors. At the approved dose, the label says the MC1 and MC4 receptors matter most.¹
• Mainly in the brain. Its developers noted that its target receptors are found mainly in the central nervous system. In rats it switched on nerve cells in the hypothalamus.⁸
• Unknown in HSDD. The label says "the mechanism by which VYLEESI improves HSDD in women is unknown."¹
• Fast and short. Blood levels peak about 1 hour after an injection, and the half-life is about 2.7 hours.¹
• Skin color. MC1 receptors control skin pigment, which helps explain the dark patches seen with frequent use.¹

Evidence map

Each claimed use is graded separately. A grade measures how much evidence exists, not whether the result was good news.

Scale: 5 FDA-approved, 4 strong human, 3 limited human, 2 animal or lab only, 1 anecdotal

Key studies

Both groups in the phase 3 trials passed the threshold for a meaningful change in desire, so the drug's added benefit is hard to judge in daily life.⁷ The trials ran in women before menopause, with HSDD not caused by illness, medicines or relationship problems.¹

By goal

Pick your goal to see what the evidence supports.

Sources: Vyleesi label,¹ Kingsberg 2019,⁴ Molinoff 2003,⁸ Palatin.¹³

How it's used

We don't give doses. For reference, the FDA label sets one for its approved use only.

Your prescriber decides whether it suits you. Compounded nasal sprays and other doses have not been tested against these label results.

Side effects and who should avoid it

• Nausea. 40% on the drug vs 1.3% on placebo. About 13% needed anti-nausea medicine and 8% stopped because of it. It usually eased by the second dose.¹
• Other common effects. Flushing in 20%, injection-site reactions in 13% and headache in 11%.¹
• Blood pressure. Each dose briefly raises blood pressure, by up to about 6 points systolic, and slows the heart rate. It usually settles within 12 hours.¹
• Dark skin patches. Seen in 1% at up to eight doses a month, and in 38% of people given eight daily doses in a separate study. Face, gums and breasts were affected, and the patches did not always fade. Darker skin raises the risk.¹
• Drug interactions. It can slow stomach emptying and sharply lower levels of oral naltrexone, so the label says to avoid it with naltrexone used for alcohol or opioid dependence.¹
• Pregnancy. Animal data suggest possible harm. The label advises effective contraception and stopping if pregnancy is suspected.¹ FDA required a pregnancy registry and a breastfeeding study at approval.^{2, 3}
• Who should avoid it. People with uncontrolled high blood pressure or known heart disease, and anyone at high cardiovascular risk.¹
• Unapproved products. Research vials and nasal sprays have no FDA check on content or dose. The nasal program was stopped over blood pressure spikes.^{9, 16}

Compared with

Sources: Vyleesi label,¹ Hadley and Dorr 2006,¹⁰ Dorr 1996,²² FDA compounding rules,¹⁴ FDA safety-risks list.¹⁹ See our melanotan II guide and our KPV guide, a small piece of α-MSH.

Stacks

PT-141 is often discussed alongside Viagra-type drugs. Palatin planned a single injection that combines the two for men who don't respond to those drugs, but we found no published results.¹² It is also mixed online with melanotan II, which adds an unapproved drug with its own skin and blood pressure risks. In 2025 Palatin reported a short phase 2 trial with tirzepatide for weight; that combination isn't approved.¹³

Myths vs evidence

All options and prices

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Brand, with a prescription

Cash prices vary by pharmacy. Insurance coverage depends on your plan and diagnosis.

Compounded bremelanotide

Federal law lets a licensed 503A pharmacy compound from an ingredient that is part of an FDA-approved drug, for a named patient's prescription.¹⁴ Bremelanotide qualifies because it is the active ingredient in Vyleesi.¹ Pharmacies may not regularly or in large amounts make what are essentially copies of an approved drug.^{14, 15} Compounded drugs are not FDA-approved, and the nasal sprays and doses sold by clinics were not the products tested in the trials. We don't link compounded versions. It isn't part of the 2026 HHS peptide policy, which it doesn't need.²⁰

Research use only products

We don't list sellers. In August 2026 FDA warned five peptide sellers, whose products included PT-141, that a "research use only" label doesn't excuse products clearly meant for people.¹⁶

Legal status history

Newest first.

1. Current statusNov 1, 2026FDA-approved as Vyleesi for acquired, generalized HSDD in premenopausal women. Not approved for men or after menopause. Not named on WADA's list.^{1, 18}
2. Next · no dateNo new approved use pending that we could find. Combination studies with other drugs are early.¹³
3. Oct 28, 2026HHS peptide compounding policy covers six other peptides. Bremelanotide isn't one; as an approved-drug ingredient it already has a compounding route.^{14, 20}
4. Oct 22, 2026FDA approves updated labeling on use in specific populations, based on the breastfeeding study it required.³
5. Aug 24, 2026FDA warning letters to "research use only" peptide sellers name PT-141 among their products.¹⁶
6. Mar 31, 2025Palatin reports a phase 2 weight trial of bremelanotide with tirzepatide.¹³
7. Dec 20, 2023Palatin sells Vyleesi to Cosette Pharmaceuticals.¹¹
8. Jul 27, 2020AMAG and Palatin end their license, and the rights return to Palatin.²³
9. Jun 21, 2019FDA approves Vyleesi, from AMAG Pharmaceuticals, and requires pregnancy and breastfeeding studies.²
10. 2008Palatin drops the nasal spray after FDA questions about blood pressure spikes raised in 2007.⁹
11. 2003Early studies in men with the nasal spray are published.⁸

FAQ

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References