PT-141 (Bremelanotide) — Research Reference
PT-141, known by its pharmaceutical name bremelanotide, is a synthetic cyclic heptapeptide (7 amino acids) and non-selective melanocortin receptor agonist. It is a metabolite of Melanotan II and was identified during research into its tanning and pigmentation effects. PT-141 is notable for being the first compound approved for the treatment of hypoactive sexual desire disorder (HSDD) in premenopausal women — approved as Vyleesi by the FDA in 2019.
Quick Reference
| Parameter | Reported Value |
|---|---|
| Full name | Bremelanotide (PT-141) |
| Amino acids | 7 (cyclic) |
| Molecular weight | ~1,025 Da |
| Half-life | ~2.7 hours (reported) |
| Common reported doses | 1–2 mg per use (not daily) |
| Administration routes | Subcutaneous injection, intranasal |
| Storage (lyophilized) | Refrigerator preferred; room temperature stable short-term |
| Storage (reconstituted) | Refrigerated; use within 4–6 weeks |
| Regulatory status | Approved pharmaceutical (Vyleesi) for HSDD in premenopausal women |
Overview
PT-141 acts primarily as an agonist at the MC1R, MC3R, and MC4R melanocortin receptors. The MC4R in particular is expressed in brain regions involved in sexual motivation and arousal. The compound’s mechanism of action in sexual response differs fundamentally from phosphodiesterase inhibitors (such as sildenafil): rather than acting peripherally on blood flow, PT-141 acts centrally on the nervous system to modulate sexual desire and motivation.
Research has investigated PT-141 for its potential role in:
- Increasing sexual desire and motivation in women with HSDD
- Improving sexual function and arousal in men with erectile dysfunction, including cases refractory to phosphodiesterase inhibitors
- Modulating central appetite and metabolic signalling via MC4R (an area of secondary research)
The FDA approval of Vyleesi in 2019 for HSDD in premenopausal women represents a significant clinical validation. Research into male sexual function continues but has not resulted in an approved indication to date.
Reported Protocols
The following information represents commonly reported research ranges and the clinical protocol associated with the approved pharmaceutical. These are not medical recommendations.
Subcutaneous Protocol (Research Context)
Subcutaneous injection is the most commonly reported administration route in anecdotal research accounts. Commonly reported doses range from 1 mg to 2 mg per use, administered 30–60 minutes before anticipated activity.
- Frequency: PT-141 is not designed for daily use. Anecdotal research accounts describe use on an as-needed basis, with most protocols describing no more than once per 48–72 hours
- Onset: Effects are reported to begin within 30–60 minutes and to persist for several hours
- No sexual stimulation required: Unlike PDE5 inhibitors, PT-141 is reported to act centrally and does not require direct sexual stimulation to produce its effects
Intranasal Protocol
Intranasal delivery has been studied in clinical trials. The intranasal route is associated with higher rates of nausea compared to subcutaneous administration in research data. Commonly reported intranasal doses in research contexts range from 1 mg to 2 mg per use.
The approved Vyleesi pharmaceutical product uses a subcutaneous autoinjector, not intranasal delivery, reflecting the tolerability advantage of the subcutaneous route.
Vyleesi (Approved Pharmaceutical)
The Vyleesi labelling specifies a single 1.75 mg subcutaneous injection administered at least 45 minutes before anticipated sexual activity. No more than one dose per 24 hours and no more than approximately eight doses per month are described in the prescribing information.
Reported Effects
The following effects have been reported in clinical research and anecdotal accounts. This list reflects the research landscape, not confirmed clinical outcomes for all individuals.
Sexual Desire and Arousal
Research has investigated PT-141 for its potential role in increasing sexual desire and subjective arousal in both men and women. Clinical trial data supporting the Vyleesi approval demonstrated statistically significant improvements in sexually satisfying events and desire scores in women with HSDD compared to placebo.
Anecdotal research accounts describe increased interest in sexual activity, heightened sensitivity, and more intense arousal in both men and women. Effects are reported to begin within 30–60 minutes of administration.
Erectile Function in Men
Research has investigated PT-141 for its potential role in erectile dysfunction, including in men who do not respond to PDE5 inhibitors. Animal research and early human studies reported penile erection via central MC4R activation. No approved indication exists for male sexual dysfunction.
Melanocortin-Related Effects
As a non-selective melanocortin agonist, PT-141 also activates MC1R, which is involved in skin pigmentation. Anecdotal reports describe transient facial flushing and, with repeated use, mild darkening of skin and moles. This effect is more pronounced with Melanotan II (a less selective compound) but is also reported with PT-141.
Reported Side Effects
Reported side effects in research and anecdotal accounts include the following. This list does not constitute a comprehensive safety profile and should not be interpreted as predictive of individual outcomes.
| Side Effect | Frequency Reported |
|---|---|
| Nausea | Very common; more pronounced with intranasal route |
| Flushing (face, neck) | Very common; typically transient |
| Headache | Common |
| Injection site reactions | Common |
| Transient blood pressure increase | Commonly reported shortly after administration |
| Fatigue | Occasionally reported |
| Hyperpigmentation (with repeated use) | Occasionally reported with prolonged use |
| Yawning | Occasionally reported (a characteristic melanocortin effect) |
Blood pressure: A transient increase in blood pressure (typically 6–8 mmHg systolic) lasting approximately 6–12 hours has been reported in clinical trial data. Vyleesi is contraindicated in individuals with established cardiovascular disease in approved clinical contexts. Researchers should be aware of this effect.
Hyperpigmentation: Repeated use may cause progressive darkening of existing moles, freckles, and skin, due to MC1R activation. This is reported more frequently in research accounts involving higher-frequency use and is noted in the Vyleesi prescribing information.
Storage & Handling
Lyophilized Powder (Unreconstituted)
- Room temperature: Reported stable for up to 3 months when kept away from light and moisture
- Refrigerator (2–8°C): Preferred for extended storage; commonly reported stable for 12 months or more
- Freezer: Acceptable for long-term storage; avoid repeated freeze-thaw cycles
- Light sensitivity: Store in an opaque or amber vial; avoid direct light exposure
Reconstituted Solution
- Refrigerator (2–8°C): Use within 4–6 weeks of reconstitution
- Do not freeze a reconstituted solution
- Bacteriostatic water (BAC water) is the standard diluent for research use multi-use vials
- Discard if the solution becomes cloudy, discoloured, or shows particulate matter
Reconstitution
Add bacteriostatic water slowly along the inside wall of the vial. Swirl gently — do not shake. See the Reconstitution Guide for step-by-step instructions.
Frequently Asked Questions
How is PT-141 different from Viagra or Cialis? PT-141 acts centrally in the brain via melanocortin receptors to increase sexual desire and motivation. PDE5 inhibitors (sildenafil, tadalafil) act peripherally by increasing blood flow to erectile tissue. They address different aspects of sexual function and may be relevant to different individuals depending on the underlying cause of dysfunction. PT-141 requires no sexual stimulation to produce its effects, unlike PDE5 inhibitors.
Is PT-141 (bremelanotide) approved? Bremelanotide is approved by the FDA as Vyleesi for the treatment of hypoactive sexual desire disorder (HSDD) in premenopausal women. No approval exists for male sexual dysfunction. Research compounds labelled PT-141 are not licensed pharmaceuticals.
How long do the effects last? Anecdotal reports describe effects beginning within 30–60 minutes of administration and persisting for 4–12 hours. Individual responses vary considerably.
Does PT-141 cause tanning? PT-141 has some activity at MC1R, the receptor involved in melanin production and skin tanning. Anecdotal reports describe mild facial flushing and, with repeated use, subtle skin darkening. This effect is more pronounced with Melanotan II. Individuals should monitor any changes to moles or skin pigmentation with repeated use.
Related Pages
Goals: Libido & Sexual Function · Fertility & Reproductive Health
Class: Melanocortin Peptides
Comparisons: PT-141 vs Melanotan II
References & Further Reading
- Clayton AH, et al. (2016). Bremelanotide for Female Sexual Dysfunctions in Premenopausal Women: A Randomized, Placebo-Controlled Dose-Finding Trial. Women’s Health Issues, 26(1), 43–50. PubMed →
- Simon JA, et al. (2019). Efficacy and safety of bremelanotide for hypoactive sexual desire disorder. Obstetrics & Gynecology, 134(5), 899–908. PubMed →
- Diamond LE, et al. (2004). PT-141: a melanocortin agonist for the treatment of sexual dysfunction. Annals of the New York Academy of Sciences, 1021, 274–281. PubMed →