PT-141
Bremelanotide · Bremelanotide · Vyleesi · PT141
Melanocortin agonist that works on desire in the brain rather than blood flow in the penis.
Typical dose
1 mg
As needed, no more than once in 24 hours and no more than 8 doses per month
Range
0.5–2
mg
Half-life
2.7 h
see Dosing
Evidence
Human trials
Subcutaneous · Intranasal
What it is
PT-141 is a cyclic seven-amino-acid melanocortin receptor agonist, structurally the deamidated metabolite of Melanotan II. It is one of the few peptides here with a licensed human product behind it: Vyleesi, approved in the US in 2019 for hypoactive sexual desire disorder in premenopausal women, delivered as a 1.75 mg subcutaneous autoinjector.
Unlike PDE5 inhibitors, PT-141 does not act on penile vasculature. It signals centrally at MC4 receptors in the hypothalamus, so the effect people report is arousal and desire rather than a mechanical erection. That makes it useful to some men who get a functional erection on tadalafil but have no drive, and useless to others who want a purely vascular fix.
The practical limits are tolerability, not efficacy. Nausea hit 40% of subjects in the phase 3 trials, flushing 20%. It also produces a small transient rise in blood pressure with a fall in heart rate, which is why the label excludes uncontrolled hypertension and known cardiovascular disease. Effect onset is slow — plan on 45 minutes minimum, often 2-4 hours.
How it works
PT-141 is a non-selective agonist at melanocortin receptors, with the sexual effect attributed mainly to MC4R in the hypothalamus and medial preoptic area. Activating those neurons increases pro-erectile and pro-appetitive dopaminergic signalling downstream, which is why the subjective report is usually "I actually want to" rather than "I got hard."
Because the pathway is central and neurochemical rather than vascular, PT-141 works upstream of nitric oxide and can be combined with a PDE5 inhibitor. The same non-selective receptor binding is why it also hits MC1R and can cause facial flushing and, with frequent dosing, focal skin darkening.
Dosing
Start at 0.5 mg to gauge nausea before going near the 1.75 mg label dose — the sickness is dose-dependent and hard to sit through if you jump straight to 2 mg.
Reconstitution calculator
Pre-loaded with PT-141’s vial size, water volume and typical dose. Change anything.
Typical: 1 mg · range 0.5–2
Draw to
40 u
0.4 mL · 1 mg
Concentration
2.5 mg/mL
25 mcg per unit
Doses per vial
5
Vial lasts
2 weeks 4 days
Draw to 40 units on the barrel.
Once mixed
Refrigerated at 2-8°C, use within about 4-6 weeks; keep it out of light and never freeze a reconstituted vial.
2 mL of bacteriostatic water into a 5 mg vial gives 2.5 mg/mL, so 1 mg is 40 units on a U-100 insulin syringe; the same 2 mL into a 10 mg vial gives 5 mg/mL and puts 1 mg at 20 units. Aim the stream down the glass wall rather than onto the powder cake and swirl gently until clear; do not shake.
Storage
Before mixing
Refrigerated at 2-8°C it is stable for 2+ years; sealed and dry at room temperature it is fine for several weeks in transit.
After mixing
Refrigerated at 2-8°C, use within about 4-6 weeks; keep it out of light and never freeze a reconstituted vial.
Reported benefits
- ▪Raises sexual desire centrally, not just erectile capacity
- ▪Works through a different pathway than PDE5 inhibitors, so it can be layered on top
- ▪Effective in women as well as men, with phase 3 data behind the female indication
- ▪Long subjective duration — arousal often persists well past the plasma half-life
- ▪As-needed dosing, no daily commitment or accumulation required
- ▪Does not suppress or interfere with the HPTA
Side effects
- ▪Nausea in roughly 40% of users, worst on the first dose and dose-dependent
- ▪Facial and upper-body flushing (~20%)
- ▪Headache (~11%) and injection site reactions
- ▪Transient rise in blood pressure with a drop in heart rate, peaking in the first hours
- ▪Focal skin hyperpigmentation with frequent or daily dosing, which may not fully reverse
- ▪Spontaneous erections and, rarely, prolonged erection at higher doses
- ▪Yawning, drowsiness and appetite loss for a few hours after injection
Do not use if
- ▪Uncontrolled hypertension or known cardiovascular disease
- ▪History of melanoma or dysplastic naevi, given melanocortin receptor activation
- ▪Pregnancy
- ▪Concurrent use with other melanocortin agonists such as Melanotan II, which compounds nausea and pigmentation without adding benefit
Evidence level — Human trials
Controlled human clinical data exists.
Approved in the US as Vyleesi (1.75 mg subcutaneous) for premenopausal HSDD; the vialled research-chemical form sold to the peptide market is not a licensed medicine.
Commonly run with
PT-141 FAQ
How long before sex should I inject?+
The label says at least 45 minutes, but most users find the peak sits somewhere between 2 and 4 hours after injection. Because the subjective effect outlasts the 2.7-hour plasma half-life, dosing in the early evening for a late night works well.
Can I take it with Cialis or Viagra?+
Yes — they act on different systems, PT-141 centrally on desire and PDE5 inhibitors peripherally on blood flow. Watch blood pressure if you are already on nitrates or antihypertensives, since PT-141 causes a small transient pressor effect of its own.
Why do I feel sick every time?+
Nausea is the main dose-limiting effect and it is caused by the same melanocortin activation that produces the benefit. Dropping to 0.5 mg, injecting on a fairly empty stomach and using an antihistamine or ondansetron beforehand are the usual workarounds; for most people the second and later doses are milder than the first.
Will it tan me like Melanotan II?+
Not meaningfully at as-needed doses. PT-141 does hit MC1R, but occasional use produces flushing rather than a tan; what does show up with frequent or daily dosing is patchy focal hyperpigmentation, notably on the face and gums, which does not always fade after stopping.
Does it affect testosterone or fertility?+
No. PT-141 acts on melanocortin receptors and has no direct effect on GnRH, LH or testicular function, so it neither suppresses nor restores the HPTA. If low libido is driven by low testosterone or high prolactin, PT-141 masks the symptom rather than fixing the cause.
References
- 1.Bremelanotide for the Treatment of Hypoactive Sexual Desire Disorder: Two Randomized Phase 3 Trials — Obstetrics and Gynecology (2019) PMID 31599840
- 2.Evaluation of the safety, pharmacokinetics and pharmacodynamic effects of subcutaneously administered PT-141, a melanocortin receptor agonist, in healthy male subjects and in patients with an inadequate response to Viagra — International Journal of Impotence Research (2004) PMID 14999221
- 3.An effect on the subjective sexual response in premenopausal women with sexual arousal disorder by bremelanotide (PT-141), a melanocortin receptor agonist — The Journal of Sexual Medicine (2006) PMID 16839319
- 4.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 dysfunction — International Journal of Impotence Research (2004) PMID 14963471
More sexual health & melanocortin
Melanotan I
Tanning-focused melanocortin agonist — the pigment of MT-II with far less nausea or erections.
500 mcg · Daily during the 10-14 day loading phase, then 1-2x weekly for maintenance
Melanotan II
Non-selective melanocortin agonist for deep tanning, with libido and nausea along for the ride.
250 mcg · Daily during the loading phase, then 1-2x weekly for maintenance