PT-141 — Bremelanotide

Background

PT-141 (bremelanotide) is a synthetic cyclic heptapeptide melanocortin receptor agonist developed by Palatin Technologies. It is marketed as Vyleesi® and is FDA-approved for the treatment of acquired, generalised hypoactive sexual desire disorder (HSDD) in premenopausal women.

Mechanism

Bremelanotide is a non-selective melanocortin receptor agonist with primary activity at MC4R and MC3R in the central nervous system. Its effect on sexual arousal is central — acting on hypothalamic and limbic circuits — rather than peripheral and vascular (the mechanism of PDE5 inhibitors like sildenafil).

What is proven

The Phase 3 RECONNECT trial program (Kingsberg et al., Obstetrics & Gynecology 2019) demonstrated statistically significant improvements in desire and distress endpoints in premenopausal women with HSDD. FDA approval (June 2019) was based on this data.

Mechanistic studies confirm central activation of arousal pathways in both sexes.

What is NOT proven (for general use)

Male efficacy beyond off-label observation: bremelanotide was studied for male erectile dysfunction in earlier development but did not achieve regulatory approval for that indication. Off-label male use is widespread but not supported by Phase 3 outcome trials at currently-used doses.

Long-term safety with frequent dosing has not been characterised. Reported adverse effects in the licensed indication include nausea (40% of users in trials), transient blood-pressure increases, and focal hyperpigmentation.

Open research questions

Definitive male efficacy data; cardiovascular safety with chronic dosing; rare but reported neurological and skin-pigmentation effects.

Regulatory status

FDA-approved (June 2019) as Vyleesi® for premenopausal HSDD. Not approved for male sexual dysfunction in any major jurisdiction.

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