PT-141 is sold to men as a libido and erection drug, and many men assume it was built for them. In a sense it was. Bremelanotide was first tested in men with erectile dysfunction, and only later developed and approved for women. What the male studies found is thinner than the marketing suggests.
The approved drug, its dose and its label are covered in the PT-141 guide. This page sits under the sexual health goal.
What the label says about men
Vyleesi, the approved form of bremelanotide, is indicated for acquired, generalized hypoactive sexual desire disorder in premenopausal women. The label states plainly that it is not indicated in men, or in postmenopausal women, and not to enhance sexual performance [1].
The label also describes the mechanism in general terms. Bremelanotide activates several melanocortin receptors, with MC1R and MC4R the most relevant at approved doses. How it improves desire in women is stated as unknown [1]. How the women’s trials came about is in the bremelanotide approval and trials.
The early studies in men
Two small placebo-controlled studies from 2004 measured erections directly, with RigiScan, a device that records penile rigidity. The first tested a nasal spray in healthy men and in men with mild to moderate erectile dysfunction who responded to Viagra [2]. Erections were significantly greater than on placebo at doses above 7 mg. The first erection came in about 30 minutes.
In that study the drug’s half-life was about 2 hours, 1.85 to 2.09 hours across doses. Flushing and nausea were the most common side effects, and no maximum tolerated dose was found [2].
The second study injected PT-141 under the skin [3]. In healthy men, doses from 0.3 mg to 10 mg were tested, and responses were significant above 1.0 mg. Men who got a poor response from 100 mg Viagra then received placebo, 4 mg or 6 mg while watching sexual video. Both doses produced significant erections compared with placebo.
These were short laboratory studies, measuring erections in a clinic for a few hours. They did not measure sexual satisfaction at home, or anything over weeks of use.
Combined with sildenafil
A 2005 crossover study gave 19 men with erectile dysfunction three combinations on different days [4]. These were 25 mg sildenafil plus 7.5 mg intranasal PT-141, sildenafil plus a placebo spray, and placebo alone. All the men already responded to a PDE5 drug.
The combination produced a significantly greater erectile response than sildenafil alone. The authors report no new adverse events and no increase in their frequency or severity compared with either drug alone [4]. Nineteen men over single study days is a signal, not a treatment result.
The parent compound, Melanotan II
A 2006 review describes PT-141 as an analog of Melanotan II, an earlier peptide tested for erectile dysfunction [7]. In a crossover study of 10 men with erectile dysfunction and physical risk factors, 12 of 19 Melanotan II injections produced erections, against 1 of 21 placebo doses [5]. Rigidity above 80% at the tip lasted 45.3 minutes on average with Melanotan II, against 1.9 minutes on placebo (P = 0.047). Sexual desire scores also rose. Nausea was common, and 4 of 19 injections caused severe nausea.
Safety points that apply to men
The label's blood pressure warning is not limited to women. In its clinical studies, bremelanotide raised systolic blood pressure by up to 6 mmHg and diastolic by up to 3 mmHg, peaking 2 to 4 hours after a dose, with heart rate falling by up to 5 beats a minute. [1]
The label contraindicates it in anyone with uncontrolled high blood pressure or known cardiovascular disease [1]. It also reports focal darkening of the skin and gums, which did not always resolve after stopping. The full adverse-effect record is in bremelanotide side effects, and the approved dose and its limits are in PT-141 dosage.
What this means for men
The male evidence for PT-141 is a handful of small, short studies of erections in a lab, and one larger trial that its journal has flagged. None of the male studies here tested men with low desire rather than erectile dysfunction. Another brain-acting approach to desire, tested in both men and women, is covered in what human studies show about kisspeptin.