Melanocortin
PT-141 (Bremelanotide)
Also known as: Bremelanotide, Vyleesi, PT141
What is PT-141?
PT-141, generic name bremelanotide, is a cyclic peptide derived from Melanotan 2. Researchers noticed that MT-2 caused sexual arousal and developed PT-141 to keep that effect while reducing tanning.
In 2019 the FDA approved it as Vyleesi, an on-demand self-injection for hypoactive sexual desire disorder (HSDD) in premenopausal women. Unlike sildenafil (Viagra), which acts on blood flow, PT-141 acts on the brain.
How PT-141 works
PT-141 activates melanocortin-4 receptors (and MC3R) in the hypothalamus, pathways involved in sexual motivation. This central action is why it was studied for desire rather than erectile mechanics. It retains some activity at MC1R, which explains the focal skin darkening seen with repeated use.
What the research shows
- Two phase 3 RECONNECT trials (about 1,250 women) showed statistically significant improvements in sexual desire and reduced distress versus placebo over 24 weeks.
- Earlier phase 2 work in men with erectile dysfunction showed erectile responses, including in sildenafil non-responders.
Compare: Melanotan 2 vs PT-141
PT-141 side effects
- Nausea — about 40% in phase 3, usually after the first dose and easing with later doses.
- Flushing, headache, injection-site reactions.
- A transient rise in blood pressure and fall in heart rate after each dose — not recommended with uncontrolled hypertension or heart disease.
- Focal hyperpigmentation (darkening of face, gums, breasts) in about 1% with repeated use.
UK legal status
Bremelanotide is not licensed in the UK or EU. Vyleesi cannot be prescribed in the UK except as an unlicensed import. PT-141 sold online is a research chemical.
More detail, including current UK research-vial prices: PT-141 UK guide. For the doses used in published studies and the reconstitution maths: PT-141 dosing in the literature.
PT-141: frequently asked questions
What is PT-141?
Bremelanotide — a melanocortin-receptor agonist approved in the US (as Vyleesi) for low sexual desire in premenopausal women.
How does PT-141 work?
It activates MC4 receptors in the brain involved in sexual motivation, rather than acting on blood flow like Viagra.
How long does PT-141 take to work?
The label advises injecting at least 45 minutes before sexual activity.
What are the side effects of PT-141?
Nausea is the most common (about 40% in trials), along with flushing, headache and a temporary rise in blood pressure.
Is PT-141 available in the UK?
It is not licensed in the UK, so it cannot be prescribed normally or sold for human use.
References
- Kingsberg SA, et al. Bremelanotide for the treatment of hypoactive sexual desire disorder: two randomized phase 3 trials. Obstet Gynecol. 2019;134:899–908.
- Diamond LE, et al. Co-administration of low doses of intranasal PT-141, a melanocortin receptor agonist, and sildenafil to men with erectile dysfunction results in an enhanced erectile response. Urology. 2005;65:755–759.
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