PT-141 Dosage: Injection vs Nasal Spray, Timing, Duration

Key takeaways

• The only labeled PT-141 dose is 1.75 mg injected under the skin of the abdomen or thigh, at least 45 minutes before anticipated sex, no more than once in 24 hours and no more than eight times a month, stopping after eight weeks if nothing has improved. It is labeled for premenopausal women only.
• Women were studied at 0.75, 1.25 and 1.75 mg; men at 0.3 to 10 mg injected and 7 to 20 mg by nasal spray, with erections at 4 and 6 mg injected in men whom sildenafil had failed.
• The nasal spray was dropped as a first-line therapy after blood pressure increases and widely varying blood levels; no modern trial has tested the 1 to 2 mg sprays sold today.
• In a 10 mg vial mixed with 2 mL, the labeled 1.75 mg dose is 35 units on a U-100 insulin syringe.

PT-141 dosing has a clearer answer than most peptides because bremelanotide is an approved drug: the Vyleesi label sets 1.75 mg under the skin, at least 45 minutes before sex, at most once a day and eight times a month. Everything beyond that, including every dose for men and every nasal spray, is off-label, and much of it is untested. This page sets the label next to the doses the trials actually used and the prescriptions compounding pharmacies fill. The PT-141 profile covers the drug in full, the guide to peptides for ED and libido ranks it against the alternatives for men, and how long PT-141 lasts covers onset, duration and why the frequency limits exist.

The labeled dose

The label explains each limit. Consecutive doses within 24 hours were never shown to work and may add to the rise in blood pressure; more than eight doses a month were rarely used in the trials and increase both skin darkening and the time each month that blood pressure is raised (Vyleesi label). In the phase 3 trials women were allowed up to 12 doses a month, but the median was 10 injections over 24 weeks and most women used it two or three times a month.

Studied doses versus compounded prescriptions

Sources: the Vyleesi label, Clayton 2016, Rosen 2004, Diamond 2004 with subject numbers and nasal dose arms from the Kim 2021 review, and Clayton 2017.

Two gaps stand out. For women, a 1 mg compounded injection sits below the only dose shown to work, since the phase 2b trial's positive result pooled the 1.25 and 1.75 mg arms (Clayton 2016). For men, the doses that produced erections in men with ED were 4 and 6 mg injected, two to three times the female label dose (Rosen 2004), which is also the range where FDA's blood pressure concern applied. A man prescribed 1 mg is taking an untested amount; a man prescribed 4 mg is taking an amount the regulator was uncomfortable with. A larger 2008 home-use trial of a 10 mg nasal spray in men carries a 2023 expression of concern, so we do not use it; the PT-141 profile explains why.

Injection versus nasal spray

Bremelanotide began as a nasal spray. Measured side by side, the two routes behave differently:

Sources: injection figures from the Vyleesi label; nasal timing and half-life from Diamond 2004; exposure from Clayton 2017 and the label.

The nose is an inefficient and inconsistent route for this peptide. Twenty milligrams by nose produced roughly the exposure of one or two 1.75 mg injections, so six to eleven times as many milligrams were needed for a similar effect on blood levels, and those levels varied from person to person. In 2007, FDA questioned the efficacy results of the male program and cited blood pressure increases as its greatest safety concern (King/Palatin 2007). In 2010, Palatin stated that blood pressure increases in some patients given nasal bremelanotide, together with significant variation in plasma levels, led it to discontinue the nasal form as a first-line therapy, and it moved to injections to get consistent levels (Palatin 2010).

What that means for a compounded spray today: no modern trial has tested one, and the sprays sold are usually labeled around 1 to 2 mg a spray, a fraction of the 7 to 20 mg that was studied. If absorption scaled with dose, which has not been shown, a 2 mg spray would deliver roughly a tenth to a fifth of the exposure of the 1.75 mg injection. The variability that worried the developer applies too: two people using the same spray may absorb very different amounts.

Timing and frequency

• At least 45 minutes before. The label's timing follows the one-hour peak; the label also says the optimal window has not been characterized and lets patients adjust it based on how they experience the effect and any nausea (Vyleesi label).
• Once in 24 hours, eight times a month. A ceiling, not a target. Daily dosing for eight days produced patches of darker skin in 38% of women in a separate study, with 14% more after another eight days.
• Eight-week checkpoint. If nothing has improved by eight weeks, the label says to stop rather than to raise the dose.

Onset, the blood pressure time course and how long nausea lasts are covered in how long PT-141 lasts.

Units for a compounded vial

Compounded bremelanotide usually arrives as a 10 mg freeze-dried vial. The arithmetic is the same for any peptide: units on a U-100 insulin syringe = dose in mcg ÷ concentration in mcg/mL × 100.

At 5,000 mcg/mL the label dose is 1,750 ÷ 5,000 × 100 = 35 units. Pharmacies differ in vial size and dilution, so use the concentration printed on your label, check it in the reconstitution calculator or the units guide, and trust the pharmacy label over either if they disagree. Mixing and injection technique are in how to reconstitute peptides and how to inject peptides.

Who should not take any dose

The label contraindicates bremelanotide in uncontrolled high blood pressure and known cardiovascular disease and does not recommend it at high cardiovascular risk; every dose raises systolic pressure by up to 6 mmHg for a few hours. It requires caution in severe kidney impairment, where exposure doubles, and in severe liver impairment, which was not studied, and contraception in women who could become pregnant. Oral naltrexone for alcohol or opioid dependence should not be combined with it (Vyleesi label). These limits apply whatever the dose or the route.

Bottom line

The PT-141 dose with evidence behind it is 1.75 mg injected, at least 45 minutes before sex, at most once a day and eight times a month, in premenopausal women. Men have studied doses but no approved one, and the doses that worked in men with ED came with a blood pressure concern that ended the program. The nasal spray is the route the developer abandoned, and today's compounded sprays deliver a fraction of what was studied. If you have a prescription, the dose on your pharmacy label is the one that counts; if your prescriber cannot tell you how it relates to the doses above, ask.

Frequently asked questions

+−What is the PT-141 dosage for men?

There is no labeled dose for men; Vyleesi is approved only for premenopausal women and its label says it is not indicated in men. The male studies used 0.3 to 10 mg under the skin in healthy men, with erections above 1 mg, and single 4 or 6 mg injections in men whom sildenafil had failed. Nasal doses of 7 to 20 mg were also studied. Compounded prescriptions for men are often 1 to 2 mg, which no study has tested, and the blood pressure concern that stopped the male program applies at any dose.

+−How much PT-141 should I inject?

The only labeled amount is 1.75 mg under the skin of the abdomen or thigh, at least 45 minutes before anticipated sex, for premenopausal women with low desire. The label caps use at one dose in 24 hours and eight doses a month, and says to stop after eight weeks if nothing has improved. Anything else is off-label, and the dose on your pharmacy label overrides any chart, including this one.

+−What is the PT-141 nasal spray dosage?

The nasal doses actually studied were 7 to 20 mg in men in the early 2000s, and 20 mg in a later safety study. Palatin dropped the spray as a first-line therapy after blood pressure increases in some patients and widely varying blood levels. Compounded sprays today are often labeled around 1 to 2 mg a spray, a small fraction of the studied amounts, and no trial has tested them, so there is no evidence-based nasal dose.

+−How many units is 1.75 mg of PT-141?

It depends on the concentration. In a 10 mg vial mixed with 2 mL of bacteriostatic water (5 mg per mL), 1.75 mg is 0.35 mL, which is 35 units on a U-100 insulin syringe; 1 mg is 20 units and 2 mg is 40 units. Mixed with 1 mL instead, 1.75 mg would be 17.5 units. Use the concentration printed on your pharmacy label and check it in a calculator.

+−How do you dose a 10 mg vial of PT-141?

A 10 mg vial holds five full doses at the labeled 1.75 mg, or ten at 1 mg. Reconstituted with 2 mL of bacteriostatic water it gives 5 mg per mL, so 1.75 mg is 35 units on a U-100 insulin syringe. The label limits use to one dose in 24 hours and eight a month; how long a vial lasts depends on use, and the beyond-use date the pharmacy prints is the limit.

+−Does PT-141 have to be injected?

The only FDA-approved form, Vyleesi, is a 1.75 mg autoinjector used under the skin. Compounding pharmacies also make nasal sprays and troches, but the sprays sold today have never been tested at their doses, and we found no published data on absorption from troches. A swallowed pill is not a realistic form for a peptide this size.

+−What is PT-141 spray used for?

It is a compounded nasal form of bremelanotide, marketed for low desire in women and erectile dysfunction in men. The nasal route is where bremelanotide began: 7 to 20 mg produced erections in laboratory studies of men. The developer abandoned it as a first-line therapy over blood pressure increases and variable blood levels, and the approved product is an injection.

+−How often can you take PT-141?

No more than one dose in 24 hours and no more than eight doses a month, according to the Vyleesi label. Doses closer together were never shown to work better and may add to the rise in blood pressure; daily dosing caused patches of darker skin in 38% of women within eight days. In the approval trials most women used it two or three times a month.

Sources

1. LabelCosette Pharmaceuticals. VYLEESI (bremelanotide injection) prescribing information, revised March 2024. DailyMed. (2024)
2. StudyClayton AH et al. Bremelanotide for female sexual dysfunctions in premenopausal women: a randomized, placebo-controlled dose-finding trial. Womens Health (Lond) 2016;12:325-37. (2016)
3. StudyRosen RC et al. 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. Int J Impot Res 2004;16:135-42. (2004)
4. StudyDiamond LE et al. 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. Int J Impot Res 2004;16:51-9. (2004)
5. ReviewKim S, Cho MC, Cho SY et al. Novel emerging therapies for erectile dysfunction. World J Mens Health 2021;39:48-64. (2021)
6. StudyClayton AH et al. Phase I randomized placebo-controlled, double-blind study of the safety and tolerability of bremelanotide coadministered with ethanol in healthy male and female participants. Clin Ther 2017;39:514-26. (2017)
7. NewsPalatin Technologies. Palatin Technologies, Inc. announces positive safety results in subcutaneous bremelanotide trial in men (nasal bremelanotide discontinued as a first-line therapy after blood pressure increases and variable plasma levels). Press release, August 17, 2010. (2010)
8. NewsKing Pharmaceuticals and Palatin Technologies. King Pharmaceuticals, Inc. and Palatin Technologies delay immediate plans for phase 3 clinical program with bremelanotide for erectile dysfunction (FDA questioned the efficacy results and cited blood pressure increases as its greatest safety concern). Press release via BioSpace, August 30, 2007. (2007)