PT-141: Complete Guide
PT-141 (bremelanotide) is a synthetic melanocortin receptor agonist derived from melanotan II. It is FDA-approved under the brand name Vyleesi for the treatment of hypoactive sexual desire disorder (HSDD) in premenopausal women. Unlike PDE5 inhibitors (Viagra, Cialis), PT-141 works centrally through the nervous system rather than directly on blood vessels, making it the first FDA-approved medication that targets desire rather than physical arousal.
Last updated: 2026-01-28
Quick Facts
- Category
- therapeutic
- Also Known As
- Bremelanotide, Vyleesi
- Related Goals
- sexual health
Who Researches PT-141?
PT-141 is researched by people dealing with low sexual desire — it's the only FDA-approved peptide that targets sexual desire through the brain rather than blood flow (like Viagra). It's specifically approved for premenopausal women with hypoactive sexual desire disorder (HSDD), but research interest extends to men and postmenopausal women as well. If you've tried PDE5 inhibitors without satisfactory results, PT-141's central nervous system mechanism offers a fundamentally different approach. Note that nausea is a common side effect that limits tolerability for some people.
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What Is PT-141?
PT-141 was discovered serendipitously during clinical trials of melanotan II, a synthetic melanocortin agonist originally developed for sunless tanning. Researchers noticed that participants experienced increased sexual arousal as an unexpected side effect. The molecule was subsequently modified to optimize melanocortin-4 receptor (MC4R) selectivity and reduce melanogenic effects, resulting in bremelanotide (PT-141).
The FDA approved PT-141 (as Vyleesi) in June 2019 for HSDD in premenopausal women — making it the first medication to target sexual desire through the central nervous system. It is available as a single-dose, pre-filled auto-injector for subcutaneous injection.
Mechanism of Action
PT-141 activates melanocortin-4 receptors (MC4R) in the hypothalamus — a brain region involved in regulating sexual desire, appetite, and energy balance. MC4R activation initiates downstream dopaminergic signaling in brain circuits associated with sexual motivation and arousal.
This central mechanism is fundamentally different from PDE5 inhibitors:
| Feature | PT-141 | PDE5 Inhibitors (Viagra/Cialis) |
|---|---|---|
| Target | Brain (MC4R in hypothalamus) | Blood vessels (PDE5 enzyme) |
| Effect | Increases desire/motivation | Increases blood flow |
| Works in women | Yes (FDA-approved) | Limited evidence |
| Route | Subcutaneous injection | Oral |
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Dosage Overview
FDA-approved dosing for Vyleesi:
- Dose: 1.75 mg subcutaneous injection
- Timing: At least 45 minutes before anticipated sexual activity
- Frequency: No more than once in 24 hours, no more than 8 doses per month
- Route: Subcutaneous injection in the abdomen or thigh
Use the peptide calculator for reconstitution of research-grade vials.
Side Effects & Safety
- Nausea (40%): The most common side effect — significantly limits tolerability for some patients
- Flushing (20%): Facial and body flushing
- Injection site reactions (13%)
- Headache (11%)
- Hyperpigmentation: Skin darkening can occur with repeated use, particularly in darker-skinned individuals
- Blood pressure: Transient increases in blood pressure; not recommended for uncontrolled hypertension or cardiovascular disease