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PT-141 Dosage Calculator and Chart | Maximum Dose and Timing
PT-141 dosage for a 10mg vial: the approved 1.75mg dose and the protocol range in units with 2mL of bac water, how often it is taken, how fast it works and how long a vial lasts.
PT-141 is bremelanotide, a seven-amino-acid ring-shaped peptide that acts on melanocortin receptors in the brain and is studied for sexual desire and arousal. Unlike most research peptides it has an approved drug behind it, so its dose has a fixed reference point: 1.75mg, taken as needed rather than on a daily schedule. One 10mg vial holds five draws at that dose.
Simms Research’s PT-141 comes in one size, a $64 vial holding 10mg, and every syringe figure here is for that vial once 2mL of bacteriostatic water is in it.
PT-141 dosage calculator
Pick the water and the dose, and the calculator gives the units to draw on a U-100 insulin syringe. It opens on a 10mg vial with 2mL and a 1.75mg dose: 35 units.
PT-141 dosage chart
Research protocols use single draws between 500mcg and 2mg, anchored on 1.75mg. Mixed at 2mL, each 10-unit mark on an insulin syringe stands for 500mcg:
| Dose | Insulin syringe units | Doses per vial |
|---|---|---|
| 250mcg | 5 units | 40 |
| 500mcg | 10 units | 20 |
| 1mg | 20 units | 10 |
| 1.5mg | 30 units | 6 |
| 1.75mg (the approved dose) | 35 units | 5 |
| 2mg | 40 units | 5 |
The approved dose lands on 35 units, a little over a third of a 1mL syringe, and 2mg is 40. Low first draws of 250 to 500mcg sit at 5 to 10 units, easier to measure on a small 30- or 50-unit syringe, where the marks sit further apart.
How much bac water for PT-141 10mg
2mL. That puts 5mg in every mL and 50mcg in every unit, so no arithmetic is needed: 10 units is 500mcg, 20 units is 1mg, 35 units is the approved 1.75mg. Some dosing sites mix the same vial with 1mL, which doubles the strength of every unit and halves each draw.
Bacteriostatic water is sterile water with a little benzyl alcohol (0.9%) added as a preservative, so a vial opened several times over the weeks stays clean. Let the water trickle along the inside of the vial instead of hitting the powder, roll it gently until the cake disappears, and the result is clear and colorless. Each step is laid out in how to reconstitute peptides.
Simms Research’s Research Water is $20 for 10mL, enough for five PT-141 vials at 2mL each; the bac water guide covers why it suits a vial kept for weeks better than plain sterile water.
For a vial mixed with another volume, another vial size, or a dose that falls between rows, the peptide calculator gives the unit count directly.
How much PT-141 to take
1.75mg, 35 units, is the dose with an approval behind it. The 2019 label for bremelanotide, sold as Vyleesi, sets one 1.75mg injection under the skin, taken as needed at least 45 minutes ahead, in a prefilled pen that holds 1.75mg in 0.3mL. It is a flat dose, not scaled to body weight.
The protocols in circulation run from 500mcg to 2mg. Most open with a test draw of 250 to 500mcg, 5 to 10 units, to see how the first dose sits, then settle between 1 and 1.75mg; 2mg, 40 units, is the usual ceiling. Going higher returns less than it adds: on the label’s own figures, blood levels rise less than in step with the dose between 0.3 and 10mg and stop climbing at about 7.5mg.
PT-141 dosage for men and women
The chart is the same for both. What differs is the research behind each: the approval rests on women, while the work in men stopped at phase 2.
PT-141 dosage for men
1 to 2mg in most protocols, 20 to 40 units. Palatin, the developer, tested injected PT-141 in healthy men at 0.3 to 10mg and measured an erectile response at doses above 1mg; men who had responded poorly to sildenafil responded at 4 and 6mg (Rosen, International Journal of Impotence Research, 2004). In the nasal-spray studies the same response needed more than 7mg (Diamond, International Journal of Impotence Research, 2004). Palatin then took the women’s indication forward, and no approval for men followed.
PT-141 dosage for women
1 to 1.75mg in most protocols, 20 to 35 units, with the approved dose as the top. A 12-week dose-finding trial in premenopausal women compared 0.75, 1.25 and 1.75mg against placebo, and the two higher doses carried the result. The two 24-week phase 3 trials that followed used 1.75mg alone, in 1,267 women.
How often PT-141 is taken
As needed, not daily. The label allows one dose in 24 hours at most and advises against more than eight in a month, which works out to about two a week. Protocols in circulation keep both limits.
The trials ran well under the cap. Women in the phase 3 studies took a median of 10 injections over 24 weeks, most of them two or three times a month and no more than once a week. The ceiling is there because frequent dosing stretches the hours each month when blood pressure sits higher and makes patches of darker skin more likely: in a separate study, 38% of people dosed every day for eight days developed them. The one time limit on the label is eight weeks, the point at which it says to stop if nothing has changed.
How long PT-141 takes to work and how long it lasts
45 minutes to an hour to work. Blood levels peak about an hour after an injection, anywhere from 30 minutes to an hour across people, and the label sets 45 minutes as the shortest lead. In Palatin’s early studies in men, the first measured response arrived at around 30 minutes.
How long it lasts is less settled. The label calls the duration of effect unknown and leaves the window to be judged dose by dose. Protocol guides put the window at several hours, tapering over roughly 4 to 12, and the single-dose study in women tracked its effects over the 24 hours that followed.
In the body it clears fast. The half-life is about 2.7 hours, so most of a dose is gone within half a day, and the small rise in blood pressure it causes returns to baseline within 12 hours (Vyleesi label, FDA, 2019).
How long a 10mg vial of PT-141 lasts
Five draws at the approved dose: about two and a half weeks at the label’s monthly ceiling, or a full four weeks on lighter schedules, where the 28-day life of a mixed vial ends it first.
| Schedule | Units per draw | One 10mg vial covers |
|---|---|---|
| 1.75mg twice a week (the monthly ceiling) | 35 units | 5 draws, about 2.5 weeks |
| 2mg twice a week | 40 units | 5 draws, about 2.5 weeks |
| 1.75mg two or three times a month | 35 units | 2 to 3 draws in 28 days |
| 1mg once a week | 20 units | 4 draws in 28 days |
| 500mcg twice a week | 10 units | 8 draws in 28 days |
On the as-needed schedules the trials used, a vial reaches its 28-day mark with peptide left in it, so the mixing date matters more than the dose count. Keep it refrigerated (36 to 46°F) once water is in. Before mixing, the freeze-dried powder copes with weeks at room temperature, so Simms Research sends it without ice, and the peptide refrigeration guide explains storage before and after mixing.
PT-141 side effects
Most doses pass without trouble, and what does come is brief. In the phase 3 trials nausea, the most common effect, reached 21% of women after their first dose and about 3% after later ones (Vyleesi label, FDA, 2019). It began within an hour and lasted about two. Across the full 24 weeks, 40% had it at least once and 8% stopped because of it (Kingsberg, Obstetrics and Gynecology, 2019), which is why protocols open with a small test draw.
Flushing followed in 20%, a reaction at the injection site in 13% (8% on placebo), headache in 11% and vomiting in 5% (Vyleesi label, FDA, 2019). Most events were mild to moderate and passed on their own. Each dose also lifts blood pressure slightly, by up to 6 points systolic and 3 diastolic at a peak two to four hours out, while the heart rate slows by up to 5 beats a minute; both settle within 12 hours (Vyleesi label, FDA, 2019). Darker patches of skin on the face, gums or breasts appeared in 1% of women at up to eight doses a month.
PT-141 nasal spray dosage
PT-141 started out as a spray, and the doses were far larger: Palatin’s nasal studies gave 7 to 20mg, and a 20mg spray turned out to deliver roughly the exposure of one or two 1.75mg injections (Clayton, Clinical Therapeutics, 2017). The spray showed effects in both sexes: erectile responses in men above 7mg, and higher reported desire in women after a single 20mg dose.
Palatin set the nose aside in 2008. Absorption swung widely from one person to the next, and the subset who took up the most saw their blood pressure climb; injected doses gave consistent, predictable blood levels, so the approved product is an injection. Everything in the chart above assumes injection.
What PT-141 is and where it came from
PT-141 is bremelanotide, a cyclic peptide that switches on the MC4 and MC3 melanocortin receptors in the hypothalamus. Drugs like sildenafil work on blood flow; PT-141 works further upstream, on the brain signals behind desire, which is why it was studied in women as well as men.
It grew out of Melanotan 2. Men in the University of Arizona tanning trials of MT2 reported spontaneous erections, and Palatin developed PT-141 from that finding. The two molecules differ only at the end of the chain, a free acid in PT-141 where MT2 has an amide, and PT-141 pulls far less on skin color. The tanning side, with its own units, is in the Melanotan 2 dosage chart. The FDA approved bremelanotide in 2019 for low sexual desire in premenopausal women.
Kisspeptin, the other peptide in this research area, acts a step earlier, on the hormone signals that run the reproductive system rather than on desire itself; its doses are in the kisspeptin dosage guide.
Frequently asked questions
How much PT-141 is too much?
In protocol terms, anything past 2mg, or a second dose inside 24 hours. Healthy men in Palatin’s early study took single doses up to 10mg, but blood levels stop rising at about 7.5mg, so draws past the usual range buy little extra exposure.
How many units of PT-141 should I take?
With 2mL in a 10mg vial, 35 units is the approved 1.75mg. The protocols in circulation span 10 to 40 units, 500mcg to 2mg, and a first test draw is usually 5 to 10.
Can PT-141 be taken every day?
Not on the label’s terms: one dose in 24 hours and no more than eight a month. Back-to-back daily runs are where the risk of darker skin patches comes from.
Does PT-141 work for men?
It was studied in men through phase 2, with measurable responses at injected doses above 1mg. The approval went to the women’s indication, so there is no approved dose for men.
Does PT-141 need to be refrigerated?
Yes after mixing: a mixed vial lives in the fridge and is finished or thrown out at 28 days. Sealed powder is stored cold as well, though it handles a few weeks of transit at room temperature.
Is PT-141 FDA approved?
Yes, as bremelanotide (Vyleesi), since 2019, for low sexual desire in premenopausal women, and not for men. Simms Research sells PT-141 strictly for lab research.