PT-141 (Bremelanotide)
Melanocortin Receptor AgonistFDA-approvedAlso known as: Bremelanotide, Vyleesi, PT141
An FDA-approved melanocortin receptor agonist that treats hypoactive sexual desire disorder (HSDD) in premenopausal women by acting directly on the central nervous system to increase sexual desire and arousal.
Overview
PT-141 (Bremelanotide) is a synthetic cyclic heptapeptide melanocortin receptor agonist, originally derived from the tanning peptide Melanotan II. During Melanotan II trials, researchers noticed significant pro-sexual side effects, leading to the development of PT-141 as a targeted sexual dysfunction treatment. Unlike PDE5 inhibitors (Viagra, Cialis) which work on the vascular system to facilitate erections, PT-141 works centrally in the brain by activating melanocortin-4 receptors (MC4R) in the hypothalamus, directly increasing sexual desire and arousal. It was FDA-approved in 2019 as Vyleesi for the treatment of hypoactive sexual desire disorder (HSDD) in premenopausal women, making it the first ever on-demand injectable medication for female sexual dysfunction. Off-label, it is widely used by both men and women for enhanced libido and sexual function.
Mechanism of Action
PT-141 works through: (1) Agonism of melanocortin-4 receptors (MC4R) in the hypothalamus and limbic system, areas involved in sexual arousal and desire; (2) Also activates MC3R and MC1R to a lesser degree; (3) Increases dopaminergic signaling in brain regions associated with sexual motivation; (4) Unlike PDE5 inhibitors, it does not directly affect blood flow or vascular smooth muscle โ the effect is purely central/neurological; (5) Increases both spontaneous and solicited sexual desire; (6) Effects on MC1R can cause mild melanogenesis (skin darkening) at higher doses; (7) MC4R activation in the brainstem can trigger transient nausea.
Molecular Formula
C50H68N14O10
Molecular Weight
1025.18 g/mol
Sequence
Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH
Dosage Protocols
Dose Range
1.75mg โ 1.75mg
Frequency
As needed, at least 45 minutes before sexual activity
Route
subcutaneous
Cycle Length
As needed (max once per 24 hours, max 8 doses/month)
FDA-approved dose. Inject in the abdomen or thigh. Onset of effect typically 45-60 minutes. Do not exceed 8 doses per month per FDA labeling.
Source: FDA prescribing information (Vyleesi)
Side Effects
| Effect | Severity |
|---|---|
| Nausea | moderate |
| Flushing | mild |
| Headache | mild |
| Injection site reactions | mild |
| Skin darkening (hyperpigmentation) | mild |
| Elevated blood pressure | moderate |
Pros & Cons
FDA-approved with clinical trial data โ the first centrally-acting drug approved for female sexual desire
Works on desire and arousal centrally โ addresses a different pathway than Viagra/Cialis
Effective in both men and women for libido enhancement
On-demand dosing โ use only when needed rather than daily
Can work when PDE5 inhibitors have failed or are contraindicated
High rate of nausea (~40%) which can be counterproductive to sexual activity
Requires subcutaneous injection โ less convenient than oral medications
Limited to 8 doses per month per FDA labeling due to skin darkening risk
Transient blood pressure elevation โ caution in cardiovascular patients
Expensive without insurance, and insurance coverage is limited
Research Studies
Legal Status
FDA-approved as Vyleesi (2019) for HSDD in premenopausal women. Prescription required. Also available through compounding pharmacies. Off-label use for male sexual dysfunction is common.
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