PT-141
Also known as Bremelanotide, Vyleesi, Bremelanotide acetate
PT-141 is a melanocortin receptor agonist that increases sexual desire and arousal by acting in the brain rather than on blood vessels. It is approved as Vyleesi for low sexual desire in premenopausal women and is widely used off-label by men and women for libido and erectile support.
Overview
PT-141, generic name bremelanotide, is a cyclic seven amino acid peptide derived from melanotan-2. During early trials of melanotan-2 as a tanning agent, male participants reported spontaneous erections, and researchers isolated the metabolite responsible. Palatin Technologies developed it first as an erectile dysfunction treatment, initially as a nasal spray, then shifted to an autoinjector for women after the nasal formulation caused blood pressure concerns. The FDA approved it in 2019 as Vyleesi for premenopausal women with hypoactive sexual desire disorder, making it one of the few approved peptides for a sexual indication.
The approval trials enrolled over 1,200 women. Bremelanotide 1.75 mg injected as needed before sexual activity produced statistically significant improvements in desire scores and reductions in distress compared to placebo, though the absolute effect was modest, and about 40 percent of participants had nausea after injection. Earlier trials in men with erectile dysfunction showed improved erections, including in men who did not respond to sildenafil, and the drug remains used off-label for that purpose even though it was never approved for men.
What makes PT-141 different from PDE5 inhibitors like sildenafil is the target. Sildenafil works on blood flow to the penis and does nothing for desire. PT-141 works on melanocortin receptors in the hypothalamus and increases the drive itself, in both sexes, with erection in men as a downstream effect. The trade-offs are nausea, flushing, and a small but consistent rise in blood pressure that lasts several hours after each dose, which is why the label limits use to one dose per day and eight per month and excludes people with uncontrolled hypertension or cardiovascular disease.
How it works
PT-141 is an agonist at melanocortin receptors, primarily MC4R and MC3R, in the hypothalamus and other brain regions involved in sexual behavior. MC4R activation in the paraventricular nucleus and medial preoptic area increases dopamine release in pathways that govern sexual motivation, which is why it raises desire rather than just physical response. In men, the same central signaling triggers erections through spinal pathways to the penis, independent of nitric oxide, which explains why it works in some sildenafil non-responders. The blood pressure increase comes from melanocortin effects on sympathetic tone. Unlike melanotan-2, PT-141 has weak activity at MC1R, so it causes little pigmentation at normal doses.
What the research shows
- human RCTBremelanotide 1.75 mg as needed improved sexual desire and reduced related distress versus placebo in premenopausal women with HSDD across two Phase 3 trials.
- human RCTNausea occurred in about 40 percent of women on bremelanotide, leading to discontinuation in around 8 percent.
- human RCTIntranasal bremelanotide produced erections in men with erectile dysfunction, including some who did not respond to sildenafil.
- human RCTBremelanotide caused transient increases in blood pressure of about 6 mmHg systolic and 3 mmHg diastolic lasting up to 12 hours.
- rodentMelanocortin agonists increase sexual motivation and erection in rodents through central MC4R and dopamine signaling.
Evidence labels: rodent and in vitro mean no human data for that finding. Human pilot means small, often uncontrolled. Human RCT means randomized and controlled. Clinical means an approved drug with regulatory data.
Dose calculator
U-100 insulin syringeUnits are a volume on the syringe, not an amount of peptide. Concentration changes every time you change the water volume. The standalone calculator explains the math.
Dosing and protocol
approved dose is 1.75 mg; many people start at 0.5-1 mg to gauge nausea
As needed
45 minutes to 2 hours before sexual activity. Effects can persist for many hours and sometimes into the next day.
| Vial | Suggested water | Concentration | Low dose draw |
|---|---|---|---|
| 10 mg | 2 mL | 5 mg/mL | 10 units |
Lyophilized: fridge or freezer, away from light. Reconstituted: fridge 2-8C, use within 4 weeks.
Cautions
- ▲Raises blood pressure for up to 12 hours after each dose; do not use with uncontrolled hypertension or cardiovascular disease, and avoid combining with stimulants.
- ▲Nausea is very common, especially at the full dose and the first few uses; it usually improves with lower doses.
- ▲Flushing, headache, and injection site reactions are frequent.
- ▲Can cause darkening of skin, gums, and moles with repeated use, particularly in people with darker skin.
- ▲Reduces absorption of oral naltrexone and may lower levels of other oral drugs by slowing gastric emptying.
Commonly stacked with
Frequently asked
How is PT-141 different from Viagra?
Sildenafil increases blood flow to the penis and only works if you are already aroused. PT-141 acts in the brain to increase the desire itself and produces erections through a separate nerve pathway. It works in both sexes, it can work in men who do not respond to sildenafil, and it can be combined with PDE5 inhibitors, though that raises the blood pressure question.
How long does it take to work and how long does it last?
Most people notice effects within 45 minutes to 2 hours, with the peak a few hours in. Increased desire can persist for the rest of the day and sometimes into the next, which some people find welcome and others find inconvenient.
How do I deal with the nausea?
Start with a lower dose, around 0.5 to 1 mg, inject on a light stomach rather than empty or full, and avoid alcohol. Nausea tends to be worst the first few times and fades with repeated use. Ondansetron helps if it is severe. Some people find the nasal route gentler.
Is the blood pressure increase dangerous?
For a healthy person, a 6 mmHg bump for several hours is not a problem. For someone with hypertension, heart disease, or who is combining it with stimulants or a PDE5 inhibitor, it can be. The label limits use to once a day and eight times a month for that reason.
References
- Bremelanotide for the treatment of hypoactive sexual desire disorder in premenopausal women: two randomized Phase 3 trials (RECONNECT). Obstetrics and Gynecology, 2019
- Efficacy and safety of intranasal bremelanotide in men with erectile dysfunction. Journal of Urology, 2004
- Vyleesi (bremelanotide injection) prescribing information. US Food and Drug Administration, 2019
- Melanocortin receptor agonists and sexual function: mechanisms and clinical potential. Pharmacology and Therapeutics, 2007