Section 01
What it's used for
Approved for low sexual desire
Approved by the FDA (as Vyleesi) for low sexual desire in premenopausal women. Two phase 3 trials (1,267 women) found statistically significant gains in desire and distress scores vs placebo. An exact responder percentage wasn't confirmed.
▸Clinical wording
PT-141 (bremelanotide, Vyleesi) is FDA-approved for hypoactive sexual desire disorder in premenopausal women. Two phase 3 RECONNECT randomized controlled trials (n=1267) demonstrated statistically significant improvement in FSFI-D sexual desire scores and FSDS-DAO distress scores compared with placebo. A specific responder-rate percentage could not be verified in the published literature, so no number is given here.
Studied for erectile dysfunction
In clinical trials, men with erectile dysfunction, including those for whom PDE5-inhibitor drugs like sildenafil hadn't worked, showed improved erections and satisfaction with PT-141, which acts on brain desire pathways, not blood flow.
▸Clinical wording
Clinical trials in men with erectile dysfunction demonstrated PT-141 efficacy, including in men who failed PDE5 inhibitor therapy. Its central mechanism addresses desire-related ED that vascular agents cannot treat. Studies show improved erections and sexual satisfaction.
Wider female sexual dysfunction
Beyond its approved use, PT-141 is being studied for wider female sexual difficulties, including problems with arousal and orgasm, based on the idea that activating desire pathways in the brain, not just blood flow, may play a role.
▸Clinical wording
Research beyond HSDD explores PT-141 for broader female sexual dysfunction, including arousal and orgasm difficulties, where central neural activation may provide benefit.
Shock studies used other drugs
In rats with severe blood loss (hemorrhagic shock), related but different drugs on the same brain receptor as PT-141 reversed shock and organ damage; PT-141 itself wasn't tested. This is animal evidence for the drug class, not for PT-141.
▸Clinical wording
In rat models of hemorrhagic shock, selective MC4 receptor agonists RO27-3225, PG-931, and NDP-MSH, not PT-141/bremelanotide itself, reversed shock and reduced multiple organ damage, apparently through central sympathetic activation and anti-inflammatory mechanisms. This is animal-model evidence for a class effect of MC4 receptor agonism in hemorrhagic shock, but no published study has tested PT-141 specifically in this setting. No clinical (human) research on this indication was found for PT-141 or other MC4 agonists.
Studied for depression symptoms
PT-141's activation of brain reward pathways is being studied for anhedonia, the loss of ability to feel pleasure seen in depression, based on the idea that problems in this same signaling system may contribute to low motivation.
▸Clinical wording
The dopaminergic and melanocortin reward pathway activation by PT-141 is being investigated for anhedonia (inability to experience pleasure) in depression, where melanocortin signaling dysfunction may contribute to motivational deficits.
Section 02
Mechanism of Action
Switches on brain circuits for desire
- The peptide switches on melanocortin receptors (MC3R and MC4R) in brain regions handling arousal and desire.
- Activating these receptors in the hypothalamus triggers nerve signals travelling down toward the genitals.
- The same signalling also adjusts the dopamine circuits that carry sexual motivation.
▸Clinical wording
MC3R/MC4R Activation in the CNS
PT-141 activates melanocortin-3 and melanocortin-4 receptors in hypothalamic and limbic brain regions involved in sexual arousal and desire. MC4R activation in the paraventricular nucleus and medial preoptic area stimulates descending pathways that enhance genital arousal responses and modulate dopaminergic circuits involved in sexual motivation.
More of the brain's reward chemical
- Receptor signalling in the hypothalamus boosts release of dopamine, the brain's reward and motivation chemical.
- The extra dopamine arrives in reward centres deep inside the brain.
- Higher dopamine tone raises sexual motivation, desire and the pleasure of the experience.
▸Clinical wording
Dopaminergic Enhancement
MC4R signaling in the hypothalamus potentiates dopamine release in the mesolimbic reward pathway (nucleus accumbens, ventral tegmental area). This enhanced dopaminergic tone increases sexual motivation, desire, and the hedonic aspects of sexual experience.
Releasing the bonding hormone
- Receptor activation in one hypothalamic nucleus triggers release of oxytocin, a bonding and arousal hormone.
- Oxytocin acts on pelvic nerves to raise genital blood flow and sensitivity in both sexes.
- It works through the rest-and-digest nerve branch and through nitric oxide signalling.
▸Clinical wording
Oxytocin Pathway Activation
MC4R activation in the paraventricular nucleus triggers oxytocin release, which contributes to genital arousal responses in both sexes. Oxytocin acts on pelvic autonomic neurons to increase genital blood flow and sensitivity through both parasympathetic and nitric oxide-mediated mechanisms.
Works in the brain, not the vessels
- Erection pills such as sildenafil and tadalafil widen genital blood vessels at the site itself.
- PT-141 instead acts centrally, on the brain circuits that start the sexual response cycle.
- Its target is desire and the behavioural side of arousal rather than local blood flow.
▸Clinical wording
Distinct from Peripheral Vasodilators
PT-141's mechanism is fundamentally different from PDE5 inhibitors. While sildenafil and tadalafil enhance peripheral genital blood flow by inhibiting PDE5 (downstream of NO signaling), PT-141 acts centrally to enhance sexual desire and the neurobehavioral components of arousal — it activates the brain circuits that initiate the sexual response cycle.
Section 03
Biological Pathways
- MC4R/Gαs/cAMP/PKA Central SignalingMC4R activation couples to Gαs, raising cAMP in hypothalamic neurons; PKA-mediated phosphorylation modulates ion channels and neurotransmitter release, enhancing excitatory signaling in arousal circuits.
- Dopamine/D1-D2 Reward PathwayMC4R-mediated dopamine release activates D1 and D2 receptors in the nucleus accumbens and prefrontal cortex; D1 activation enhances approach motivation, while D2 signaling modulates reward sensitivity.
- Oxytocin/PVN Autonomic PathwayPVN oxytocin neurons project to sacral parasympathetic nuclei, activating pelvic nerve pathways that increase genital blood flow, lubrication, and tissue engorgement through NO-mediated vasodilation.
- Endorphin/Opioid ModulationMC4R signaling modulates endogenous opioid release, contributing to the pleasurable, rewarding aspects of arousal, part of the broader melanocortin-opioid axis in reward and motivation.
Section 04
Dosage Information
Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH| Route / system | Context | Range studied | Limitation |
|---|---|---|---|
| Subcutaneous — approved label | Official label (Vyleesi), low desire before menopause | 1.75 mg from a pre-filled autoinjector at least 45 min before sex — about 19–25 µg/kg at 70–90 kg; at most one dose per 24 h, 8 a month | Approved only for acquired, generalised low desire before menopause — not for men, not after menopause. The monthly cap is all the exposure trials covered. |
| Subcutaneous — male erection trials | Phase 1/2 dose-finding, men with erection problems, 2004 | Single doses of 0.3–10 mg; the erection response became significant above 1.0 mg. The approved 1.75 mg sits near the bottom | Single doses in a lab, erections logged by a device rather than reported by the men. No phase 3 in men was ever run, so repeated use in men is untested. |
| Intranasal — discontinued programme | Male trials halted in 2007 over blood pressure | 4–20 mg per dose, erection response significant above 7 mg; a separate study paired 7.5 mg in the nose with 25 mg sildenafil | Dropped: nasal absorption varied so widely that some doses raised blood pressure. No nasal product was approved, and sprays sold today match no dose here. |
| Subcutaneous — self-administration | Circulating practice in men, outside any trial | A 0.5–1 mg test dose, then 1.25–1.75 mg about 45 minutes before sex — about 6–25 µg/kg for a 70–90 kg adult | Practice, not a finding: the numbers come from a women's label, rounded to what a compounded vial holds. Repeated exposure in men was never measured. |
Results
Syringe Fill Level (100u syringe)
Set positive values for: Recommended dose per kg.
Research Use Only. This information is for educational and research purposes only. Not intended for medical advice or self-medication.
Section 05
Protocols
- Protocol 01
PT-141 Libido Enhancement
FDA-approved peptide for sexual dysfunction and libido enhancement. Works through nervous system.
- Focus
- Sport & Performance
- Level
- Beginner
- Duration
- As needed
Section 06
Stability & Storage
Lyophilised powder
Research-grade PT-141 ships as lyophilised powder, kept at −20°C for long-term stability (18-24 months) or at 2-8°C for up to 6 months. Commercial ready-to-use auto-injectors (Vyleesi) contain a pre-mixed solution and are stored at controlled room temperature (20-25°C) with a 2-year shelf life. The cyclic structure gives the peptide extra resistance to protease breakdown compared with linear peptides.
After reconstitution
Reconstituted with bacteriostatic water, the solution is kept at 2-8°C and used within 21-28 days. It stays stable at physiological pH and is not significantly affected by light exposure.
Section 07
Side Effects & Precautions
Most reported effects with PT-141 are documented by frequency and timing from clinical trials, ranging from common nausea to a transient rise in blood pressure that shapes how often it can be dosed.
Nausea and Flushing
- Nausea is the most common effect (40% in trials): starts 1-2 hours after injection, lasts 2-4 hours, via MC4R activity in the brain's nausea center (area postrema).
- Flushing of the face and body occurs in about 20% of users, from melanocortin-mediated widening of blood vessels, and is usually transient (30-60 minutes).
Injection Site Reactions and Headache
Mild pain, redness, or bruising at the injection site occurs in about 13% of users, typical for subcutaneous peptide injections. Headache is reported in about 11% of patients, usually mild and self-limiting.
Blood Pressure Effects and Dosing Limits
- PT-141 can raise blood pressure by 5-10 mmHg for 6-12 hours after injection, and is contraindicated in uncontrolled high blood pressure or significant heart disease.
- FDA labeling limits dosing to one dose per 24 hours and no more than 8 doses per month, to limit cardiovascular and other side effects.
Skin Darkening With Repeated Use
Despite lower activity at the MC1R receptor than Melanotan II, PT-141 can still cause some skin darkening with repeated use, particularly in people with darker baseline skin tones. This effect is generally mild and reversible.
Section 08
Regulatory Status
The approval is also narrower than the peptide's broader reputation suggests — it covers one diagnosis, in one patient group, at one fixed dose.
FDA / United States
Approved as Vyleesi since 2019
The FDA approved bremelanotide as Vyleesi in June 2019 for acquired, generalized hypoactive sexual desire disorder (HSDD) in premenopausal women. It ships as a prescription-only 1.75 mg subcutaneous auto-injector, developed by Palatin Technologies and sold today by Cosette Pharmaceuticals, which acquired the product in December 2023.
Prescribing limits
The approval is narrow, with real limits
Vyleesi is indicated only for generalized HSDD, not for desire problems caused by a relationship, a medical condition or a medication. It is contraindicated in uncontrolled hypertension and capped at 8 injections per month.
EU / Europe
Not approved; no EMA filing
Bremelanotide has never received a marketing authorisation from the EMA, and as of 2026 no formal application has gone through the centralised procedure. PT-141 sold in Europe outside a clinical trial is not an approved medicine.
WADA
Not explicitly named as of 2026
The current Prohibited List does not name bremelanotide, and its mechanism (MC3R/MC4R agonism) does not fall cleanly under an existing S2 subsection. This can change with any future revision, so competing athletes should check the current list themselves.
Regulatory status differs sharply by geography and by product: the same molecule can be an approved medicine, an unapproved import and a research chemical at once, depending on where and how it is sold. Check the current documents of your own regulator before relying on any of this.
Section 09
Research Studies
- [1]PT-141: A Melanocortin Agonist for the Treatment of Sexual DysfunctionMolinoff PB, Shadiack AM, Earle D, Diamond LE, Quon CY. · Annals of the New York Academy of Sciences · 2003
- [2]Selective facilitation of sexual solicitation in the female rat by a melanocortin receptor agonistPfaus JG, Shadiack A, Van Soest T, Tse M, Molinoff P. · Proceedings of the National Academy of Sciences · 2004
- [3]Central control of penile erection: Role of the paraventricular nucleus of the hypothalamusArgiolas A, Melis MR. · Progress in Neurobiology · 2005
- [4]Effect of an alpha-melanocyte stimulating hormone analog on penile erection and sexual desire in men with organic erectile dysfunctionWessells H, Gralnek D, Dorr R, Hruby VJ, Hadley ME, Levine N. · Urology · 2000
- [5]Double-blind, placebo-controlled evaluation of the safety, pharmacokinetic properties and pharmacodynamic effects of intranasal PT-141, a melanocortin receptor agonist, in healthy males and patients with mild-to-moderate erectile dysfunctionDiamond LE, Earle DC, Rosen RC, Willett MS, Molinoff PB. · International Journal of Impotence Research · 2004
- [6]An Effect on the Subjective Sexual Response in Premenopausal Women with Sexual Arousal Disorder by Bremelanotide (PT-141), a Melanocortin Receptor AgonistDiamond LE, Earle DC, Heiman JR, Rosen RC, Perelman MA, Harning R. · The Journal of Sexual Medicine · 2006
- [7]Bremelanotide for Female Sexual Dysfunctions in Premenopausal Women: A Randomized, Placebo-Controlled Dose-Finding TrialClayton AH, Althof SE, Kingsberg S, et al. · Women's Health · 2016
- [8]Bremelanotide for the Treatment of Hypoactive Sexual Desire Disorder: Two Randomized Phase 3 TrialsKingsberg SA, Clayton AH, Portman D, et al. · Obstetrics & Gynecology · 2019
- [9]Long-Term Safety and Efficacy of Bremelanotide for Hypoactive Sexual Desire DisorderSimon JA, Kingsberg SA, Portman D, et al. · Obstetrics & Gynecology · 2019
- [10]Bremelanotide: First ApprovalDhillon S, Keam SJ. · Drugs · 2019
Section 10
Frequently Asked Questions
Yes, for its approved use: two phase 3 trials in 1,267 premenopausal women with hypoactive sexual desire disorder showed statistically significant improvement in desire scores and related distress versus placebo, and it's FDA-approved on that basis. In men, early trials for erectile dysfunction — including in men who didn't respond to PDE5 inhibitors — showed improved erections, but no phase 3 trial in men was ever completed, so it isn't approved for male use.
The label directs it to be given at least 45 minutes before anticipated sexual activity, with dosing limited to once per 24 hours. Nausea and injection-site effects are reported to start 1 to 2 hours after injection and last 2 to 4 hours, which gives a rough sense of how long the compound stays active, though a precise duration-of-effect window isn't part of the approved labeling.
It's FDA-approved only for premenopausal women with acquired, generalized hypoactive sexual desire disorder. Phase 1/2 trials in men with erectile dysfunction, using single doses of 0.3 to 10 mg, showed a significant erection response above 1 mg, but the male program stopped there — no phase 3 trial in men was run, and repeated dosing in men has never been studied.
This isn't addressed in the approved PT-141/Vyleesi label, which doesn't cover use alongside PDE5 inhibitors. The two act through different mechanisms — PT-141 centrally on desire, sildenafil and tadalafil peripherally on blood flow — but no combination trial data appears in the sourcing here.
Nausea is most common, reported in about 40% of trial participants, typically starting 1 to 2 hours after injection and lasting 2 to 4 hours. Flushing occurs in around 20%, injection-site reactions in 13%, headache in 11%, and blood pressure can rise transiently by 5 to 10 mmHg for 6 to 12 hours — hence the contraindication in uncontrolled hypertension. Some skin darkening has also been reported with repeated use, a carryover from its relation to the tanning peptide Melanotan II, described as mild and reversible.
It's FDA-approved by prescription (as Vyleesi) for its specific indication, so it's legal as a prescription drug in the US within that use. WADA doesn't specifically list PT-141 on its Prohibited List, though melanocortin agonists could potentially fall under other categories depending on interpretation — the sourcing here gives no definitive sport-status ruling.
The commercial Vyleesi auto-injector is pre-mixed and stored at controlled room temperature, 20 to 25 °C, with a 2-year shelf life. Research-grade lyophilized powder is different — kept at −20 °C for 18 to 24 months or 2–8 °C for up to 6 months — and once reconstituted it's kept at 2–8 °C and used within 21 to 28 days.