PT-141Bremelanotide (Vyleesi)
A synthetic peptide that activates melanocortin receptors in the brain to enhance sexual function. Unlike Viagra, PT-141 works through the central nervous system rather than blood flow mechanisms.
FDA-Approved as Vyleesi
Bremelanotide was FDA-approved in June 2019 for premenopausal women with Hypoactive Sexual Desire Disorder (HSDD). It is the second medication ever approved for low sexual desire in women.
Key Takeaways
Central Mechanism
Activates MC3R and MC4R melanocortin receptors in the brain to enhance sexual desire and arousal
FDA-Approved (Vyleesi)
Approved for premenopausal women with HSDD. Administered via subcutaneous injection
Melanotan II Derivative
Developed after researchers observed pro-sexual effects during tanning peptide studies
Novel Approach
Works through brain arousal pathways rather than peripheral blood flow like Viagra
Clinical Evidence
Demonstrated significant improvements in sexual desire and distress scores in Phase 3 trials
Common Side Effects
Nausea (40%), flushing (20%), and transient blood pressure changes are most common
What is PT-141?
PT-141, known by its pharmaceutical name bremelanotide, is a synthetic cyclic heptapeptide that acts as an agonist at melanocortin receptors, particularly MC3R and MC4R. Unlike traditional treatments for sexual dysfunction that target peripheral mechanisms, PT-141 works through the central nervous system to modulate sexual arousal and desire.
The peptide's development represents one of the most fascinating examples of serendipitous drug discovery. PT-141 emerged from research on Melanotan II (MT-II), a synthetic analog originally designed to induce skin tanning without UV exposure. During clinical studies, researchers observed unexpected pro-sexual effects in both male and female participants.
The Melanocortin System
PT-141 belongs to the class of melanocortin receptor agonists. The melanocortin system plays crucial roles in:
PT-141 vs Vyleesi
Vyleesi (FDA-Approved)
Indication
Premenopausal women with acquired, generalized HSDD
Dosage
1.75 mg subcutaneous, at least 45 min before activity
Limits
Max 1 dose per 24 hours, max 8 doses per month
Administration
Single-use autoinjector
Research PT-141
Applications
- • Male erectile dysfunction studies
- • Melanocortin receptor pharmacology
- • Central arousal mechanisms
Status
Research compound - not FDA-approved for these uses
Note
Quality and purity may vary between sources
Molecular Structure
Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH
Core cyclic sequence (Asp-His-DPhe-Arg-Trp-Lys) with N-terminal Ac-Nle
Chemical Properties
- • Formula: C₅₀H₆₈N₁₄O₁₀
- • MW: 1025.18 Da
- • Water soluble
- • CAS: 189691-06-3
Key Features
- • Cyclic structure = metabolic stability
- • D-Phenylalanine = receptor selectivity
- • Ac-Nle N-terminus = unique profile
- • Reduced tanning vs MT-II
How PT-141 Works
PT-141's mechanism represents a paradigm shift in understanding sexual dysfunction treatment. Unlike PDE5 inhibitors that act peripherally on blood vessels, PT-141 engages central nervous system pathways that regulate sexual desire and arousal.
Melanocortin 3 Receptor
- Located in hypothalamus, limbic system
- Involved in energy homeostasis
- Modulates reward and motivation
Melanocortin 4 Receptor
- Highly expressed in hypothalamus
- Critical for sexual behavior regulation
- Mediates erectile function centrally
Central Nervous System Pathways
Activates neurons in medial preoptic area and paraventricular nucleus
Triggers downstream dopamine release in reward/motivation areas
May stimulate oxytocin from paraventricular nucleus
Melanocortin receptors influence erectile and ejaculatory reflexes
Research Overview
RECONNECT Pivotal Trials
Two Phase 3 randomized, double-blind, placebo-controlled trials formed the basis for FDA approval:
Study Design
- • Premenopausal women with HSDD
- • 1.75 mg bremelanotide vs placebo
- • 24 weeks at-home use
- • As-needed before sexual activity
Results
- • Significant improvement vs placebo
- • FSFI desire: ~0.5 points greater
- • FSDS-DAO distress: ~0.7 points greater
- • 25% vs 17% meaningful improvement
Male Erectile Dysfunction Research
Although not FDA-approved for men, substantial research has explored PT-141 for erectile dysfunction:
Subcutaneous PT-141 induced erections in men with ED
Efficacy observed in men who failed sildenafil therapy
May benefit psychogenic ED or desire disorders
Note: Development for male ED was discontinued due to blood pressure concerns with the intranasal formulation and competitive landscape (multiple PDE5 inhibitors available).
PT-141 vs Viagra (PDE5 Inhibitors)
| Factor | PT-141/Bremelanotide | PDE5 Inhibitors |
|---|---|---|
| Primary Target | Brain (CNS) | Penis/vasculature |
| Mechanism | MC3R/MC4R activation | cGMP preservation |
| Effect on Desire | Enhances | No direct effect |
| Requires Stimulation | Less dependent | Yes |
| Administration | Subcutaneous injection | Oral tablet |
| Works in Women | FDA-approved for HSDD | Not effective |
| Common Side Effects | Nausea, flushing, BP changes | Headache, flushing, dyspepsia |
Complementary Roles
Rather than competing treatments, they may serve complementary roles:
- PDE5 inhibitors: When the primary problem is achieving/maintaining erection despite adequate desire
- PT-141: When desire or central arousal is deficient, or when PDE5 inhibitors have failed
Dosage Information
FDA-Approved (Vyleesi)
1.75 mg subcutaneous injection
At least 45 minutes before activity
Max 1 dose/24h, max 8 doses/month
Abdomen or thigh
Pharmacokinetics
Side Effects & Safety
Common Side Effects
Blood Pressure Effects
- • Mean increase: 6/3 mmHg systolic/diastolic
- • Peak effect: 2-3 hours post-dose
- • Returns to baseline: 6-8 hours
- • Clinically significant increases (>20 mmHg) occur in some patients
Contraindications
Absolute:
- • Uncontrolled hypertension
- • Known cardiovascular disease
- • Hypersensitivity to bremelanotide
Precautions:
- • Severe hepatic impairment
- • Severe renal impairment
- • Pregnancy/breastfeeding
- • Concomitant oral naltrexone
Frequently Asked Questions
References
- Pfaus JG, et al. "The melanocortin system and the sexual arousal response." Journal of Sexual Medicine. 2009;6(11):3008-3022.
- Hadley ME, Dorr RT. "Melanocortin peptide therapeutics: historical milestones, clinical studies and commercialization." Peptides. 2006.
- U.S. FDA. "FDA approves new treatment for hypoactive sexual desire disorder in premenopausal women." FDA News Release. June 21, 2019.
- Kingsberg SA, et al. "Bremelanotide for the treatment of hypoactive sexual desire disorder." Obstetrics & Gynecology. 2019;134(5):899-908.
- Diamond LE, et al. "Double-blind evaluation of intranasal PT-141 in healthy males." Int Journal of Impotence Research. 2004;16(1):51-59.
- Vyleesi [package insert]. Waltham, MA: AMAG Pharmaceuticals, Inc.; 2019.
This article is for educational and informational purposes only. It does not constitute medical advice, diagnosis, or treatment. Vyleesi is available by prescription only and requires evaluation by a licensed physician.
Last Updated: March 2026
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