What the Research Found

Bremelanotide has been studied in animals, in men with erectile dysfunction and, most thoroughly, in women with low sexual desire.

Animal Studies

In a 2004 study in female rats, PT-141 increased the behaviours rats use to invite a partner, without changing the physical mating reflex. Researchers saw this as a sign that it acts on desire rather than on the mechanics of sex, an idea that shaped its later development.

Men With Erectile Dysfunction

• Nasal spray (Int J Impot Res, 2004): in healthy men and in men with mild to moderate erectile dysfunction, PT-141 produced erections compared with placebo, starting about half an hour after use. Flushing and nausea were the most common side effects.
• Injection (Int J Impot Res, 2004): injected PT-141 caused erections in healthy men without sexual images, and in men who did not respond well to sildenafil.
• Together with sildenafil (Urology, 2005): in 19 men, adding a low dose of the nasal spray to a low dose of sildenafil gave a stronger erectile response than sildenafil alone, with no new side effects.

Women With Low Desire

• First study in women (J Sex Med, 2006): among 18 premenopausal women with arousal disorder, more reported moderate or high desire after a single nasal dose than after placebo.
• Dose-finding trial (Womens Health, 2016): over 12 weeks, the two higher strengths raised the number of satisfying sexual events and reduced distress compared with placebo, but by less than one extra satisfying event a month.
• RECONNECT trials (Obstet Gynecol, 2019): 1,267 women with an average age of 39 used bremelanotide or placebo as needed for 24 weeks. Desire scores rose, and distress about low desire fell, significantly more with bremelanotide.
• Open-label extension (Obstet Gynecol, 2019): 684 women carried on for another 52 weeks and 272 finished. The most common side effects were nausea in about four in ten, flushing in about one in five and headache in about one in eight.

Criticism

A 2024 analysis by independent psychologists argued that the questionnaires used in RECONNECT had little proof of validity for women with low desire, that most planned outcomes had not been published and that the overall benefits were statistically modest. A 2026 commentary went in another direction and asked whether the drug should be studied in men with low desire.

Limits of the Evidence

• Most trials were funded or run by the companies developing the drug.
• The phase 3 trials mainly involved white women in the United States.
• Postmenopausal women and men with low desire were not part of the approval trials.
• The studies in men used early forms of the drug and lasted only days or weeks.

Summary

PT-141 does affect sexual response, in men and in women. In the trials that led to approval it brought small but measurable gains in desire and less distress, at the price of frequent nausea. How much difference that makes in everyday life is still debated.

References

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2. Diamond LE, Earle DC, Rosen RC, Willett MS, Molinoff PB. Double-blind, placebo-controlled evaluation of the safety, pharmacokinetic properties and pharmacodynamic effects of intranasal PT-141, a melanocortin receptor agonist, in healthy males and patients with mild-to-moderate erectile dysfunction. Int J Impot Res. 2004;16:51-59. PMID 14963471
3. Rosen RC, Diamond LE, Earle DC, Shadiack AM, Molinoff PB. Evaluation of the safety, pharmacokinetics and pharmacodynamic effects of subcutaneously administered PT-141, a melanocortin receptor agonist, in healthy male subjects and in patients with an inadequate response to Viagra. Int J Impot Res. 2004;16:135-142. PMID 14999221
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10. Kingsberg SA, Clayton AH, Portman D, et al. Bremelanotide for the treatment of hypoactive sexual desire disorder: two randomized phase 3 trials. Obstet Gynecol. 2019;134:899-908. PMID 31599840
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