Also known as: Bremelanotide, Vyleesi, PT141
Treatment of hypoactive sexual desire disorder (HSDD) in premenopausal women (FDA-approved as Vyleesi)
Amount
1.75 mg
Frequency
As needed (PRN), at least 45 minutes before anticipated sexual activity
Duration
Ongoing as needed; no more than 8 doses per month
Route
SCSchedule
As needed (PRN), at least 45 minutes before anticipated sexual activity
Timing
At least 45 minutes before anticipated sexual activity; peak plasma at ~1 hour
โ Rotate injection sites
Duration
Ongoing as needed; no more than 8 doses per month
Repeatable
Yes
โ Ready-to-use โ no reconstitution required
Storage: Vyleesi auto-injectors should be stored at 20-25 degrees Celsius (68-77 degrees Fahrenheit). Excursions permitted to 15-30 degrees Celsius. Protect from light. Do not freeze. For research-grade lyophilized PT-141, store powder at -20 degrees Celsius. Reconstituted solutions should be refrigerated at 2-8 degrees Celsius and used within 30 days.
Blood pressure
When: Baseline
Why: PT-141 causes transient BP increases; baseline assessment essential
CBC
When: Baseline
Why: General health baseline
CMP
When: Baseline
Why: Liver and kidney function (65% renally excreted)
Melanocyte assessment (skin exam)
When: Baseline
Why: MC1R activation can cause focal hyperpigmentation
Blood pressure monitoring
When: With first few doses
Why: Transient BP increase occurs with each dose; verify return to baseline
Blood pressure
When: Ongoing
Why: Transient increases expected; persistent elevation warrants discontinuation
โ ๏ธ Transient increases expected; persistent elevation warrants discontinuation
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PT-141, known by its generic name bremelanotide and marketed under the brand name Vyleesi, is a synthetic cyclic heptapeptide that acts as a non-selective agonist at melanocortin receptors, with particular relevance to the melanocortin-4 receptor (MC4R) in the central nervous system. It was approved by the U.S. Food and Drug Administration on June 21, 2019, for the treatment of hypoactive sexual desire disorder (HSDD) in premenopausal women, making it one of very few FDA-approved treatments for female sexual dysfunction.
PT-141 was developed by Palatin Technologies and is manufactured and distributed by AMAG Pharmaceuticals. Its development history traces back to Melanotan-2 (MT-2), a broader melanocortin agonist originally studied for skin tanning and sexual function. During clinical trials of Melanotan-2, researchers observed unexpected pro-sexual effects, which led to the development of PT-141 as a more targeted compound optimized for sexual function rather than melanogenesis.
The amino acid sequence of PT-141 is: Ac-Nle-c[Asp-His-D-Phe-Arg-Trp-Lys]-OH
This cyclic structure, formed by a lactam bridge between the aspartate and lysine side chains, distinguishes PT-141 from its linear parent peptide alpha-MSH and contributes to its improved metabolic stability and receptor selectivity.
PT-141 exerts its effects through activation of melanocortin receptors, particularly MC4R in the central nervous system. The melanocortin system is an ancient neuroendocrine pathway involved in regulating diverse physiological functions including appetite, energy homeostasis, pigmentation, inflammation, and sexual behavior.
PT-141 binds to and activates multiple melanocortin receptor subtypes:
The MC4R activation in the hypothalamus is the primary mechanism relevant to PT-141's therapeutic effects on sexual desire.
PT-141 acts in the brain, not at peripheral tissues, which fundamentally distinguishes it from PDE5 inhibitors (sildenafil, tadalafil) that work by increasing blood flow to genital tissues. The specific neural pathway involves:
This central mechanism means that PT-141 addresses the motivational and desire components of sexual function rather than the peripheral arousal response, making it fundamentally different from treatments like sildenafil or testosterone.
The FDA approval of PT-141 was based on two identical Phase 3, randomized, double-blind, placebo-controlled trials known as RECONNECT (Studies 301 and 302). These trials enrolled 1,267 premenopausal women with HSDD across multiple U.S. centers.
Key results from the RECONNECT trials:
PT-141 (Vyleesi) was approved on June 21, 2019, with the following label specifications:
A 52-week open-label extension of the RECONNECT trials demonstrated sustained efficacy with a favorable safety profile. The most common treatment-emergent adverse events during the extension were nausea (40.4%), flushing (20.6%), and headache (12.0%).
PT-141 is a metabolite of Melanotan-2 (MT-2) and shares structural elements with it. However, there are important differences:
| Feature | PT-141 (Bremelanotide) | Melanotan-2 |
|---|---|---|
| Structure | Cyclic heptapeptide | Linear/cyclic decapeptide |
| Amino acids | 7 | 10 |
| Primary effect | Sexual desire (MC4R) | Tanning + sexual function |
| FDA status | Approved (Vyleesi) | Not approved |
| MC1R activity | Lower | Higher (melanogenesis) |
| Development stage | Marketed product | Research compound |
| Administration | SC auto-injector | SC injection |
The key structural difference is that PT-141 was designed to retain MC4R-mediated sexual function effects while reducing the MC1R-mediated tanning effects that characterized Melanotan-2.
PT-141 has been studied in Phase 2 clinical trials for erectile dysfunction (ED) in men. Early clinical data demonstrated statistically significant improvements in erectile function. Palatin Technologies initiated a Phase 2 study of bremelanotide co-administered with a PDE5 inhibitor for ED in patients who do not respond to PDE5 inhibitor monotherapy.
The mechanism in men is the same as in women: central MC4R activation increasing dopaminergic signaling involved in sexual motivation and arousal. This is complementary to PDE5 inhibitors, which act peripherally on blood flow.
The safety profile from clinical trials and post-marketing experience shows:
Despite FDA approval, several areas remain incompletely characterized:
Bremelanotide for the Treatment of Hypoactive Sexual Desire Disorder: Two Randomized Phase 3 Trials, published in Obstetrics and Gynecology (Kingsberg SA et al., 2019; PMID: 31599840):
Pivotal RECONNECT Phase 3 trials demonstrating bremelanotide 1.75 mg SC significantly improves sexual desire and reduces distress in premenopausal women with HSDD compared to placebo.
Safety Profile of Bremelanotide Across the Clinical Development Program, published in Journal of Women's Health (Clayton AH et al., 2022; PMID: 35147466):
Comprehensive safety analysis across the bremelanotide clinical development program including Phase 3 trials and open-label extensions. Demonstrates favorable overall safety profile with primarily mild to moderate adverse events.
The neurobiology of bremelanotide for the treatment of hypoactive sexual desire disorder in premenopausal women, published in CNS Spectrums (Pfaus JG et al., 2022; PMID: 33455598):
Detailed review of bremelanotide's neurobiological mechanism of action, including MC4R activation in the hypothalamus, dopaminergic pathway modulation, and effects on brain regions involved in sexual motivation.
Melanocortins in the treatment of male and female sexual dysfunction, published in Current Topics in Medicinal Chemistry (Shadiack AM et al., 2007; PMID: 17584134):
Review of melanocortin agonists including bremelanotide for both male and female sexual dysfunction, describing the rationale for MC4R targeting and early clinical development results.
Bremelanotide: New Drug Approved for Treating Hypoactive Sexual Desire Disorder, published in Annals of Pharmacotherapy (Mayer D and Lynch SE, 2020; PMID: 31893927):
Clinical pharmacy review of bremelanotide following FDA approval, summarizing pharmacology, clinical trial data, safety profile, dosing, and place in therapy for HSDD.
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LIB-01: first-in-class oral MC4R-modulating compound for erectile dysfunction by Dicot Pharma. Phase 2a results, unique month-long duration of action from 3-day dosing.
Melanotan-1 (Afamelanotide): Approved alpha-MSH analog. Covers melanocortin mechanism, Scenesse for EPP, photoprotective tanning, and safety data.
This website is for educational and informational purposes only. The information provided is not intended to diagnose, treat, cure, or prevent any disease. Always consult with a qualified healthcare professional before using any peptide or supplement.
Alprostadil and PT-141 target fundamentally different aspects of sexual dysfunction and are not direct competitors. Alprostadil is the established choice for male erectile dysfunction, producing reliable erections through direct peripheral vasodilation regardless of the underlying cause. PT-141 addresses the central desire deficit that PDE5 inhibitors and alprostadil cannot reach, making it uniquely relevant for hypoactive sexual desire disorder. The choice depends entirely on the clinical problem โ mechanical erectile failure versus diminished sexual desire โ and in some cases both mechanisms may be complementary.
PT-141 is the clear winner for anyone seeking an evidence-based peptide for sexual function, with FDA approval, defined dosing, and a characterized safety profile. Melanotan-2 remains the more pharmacologically diverse compound with broader melanocortin effects including tanning, but its lack of regulatory approval and wider side effect profile reflect its status as an unrefined parent compound. PT-141 represents what happens when a promising lead compound is properly developed through clinical trials, while MT-2 remains in the research domain with significant safety concerns.
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