PT-141 is the research name for bremelanotide, sold as Vyleesi. Unlike most peptides, it has an FDA label, so the dose question has a written answer: one strength, taken only when needed. [1]
This page covers that dose, where it came from and the limits placed around it. How the drug was approved is covered in the PT-141 approval and trials, and the wider options sit on the sexual health goal page.
What the label states
The label’s dose is 1.75 mg injected under the skin of the abdomen or thigh, as needed, at least 45 minutes before expected sexual activity [1]. It comes as a single-dose autoinjector holding 1.75 mg in 0.3 mL, so there is no dose to measure or adjust.
| Rule | What the label states |
|---|---|
| Dose | 1.75 mg under the skin, abdomen or thigh |
| Timing | At least 45 minutes before expected sexual activity |
| Per day | No more than one dose in 24 hours |
| Per month | More than 8 doses a month is not recommended |
| When to stop | After 8 weeks if desire has not improved |
| Who it is for | Premenopausal women with acquired, generalized HSDD |
The label is equally clear about who the dose is for. It is not indicated in women after menopause or in men, and it is not indicated to enhance sexual performance [1].
Why 45 minutes, and why once a day
The timing follows from how quickly the drug is absorbed and cleared. The label gives a median time to peak blood level of about 1 hour, with nearly 100% of the injected dose reaching the blood, and a half-life of about 2.7 hours [1]. A dose taken 45 minutes ahead is near its peak when it is meant to act.
The label also admits the limit of that reasoning. It says how long each dose works is unknown, and that the best time to inject has not been fully worked out, so patients may adjust the timing to how the effect and any nausea feel to them.
The one-a-day rule is about blood pressure. Each dose raised systolic pressure by up to 6 mmHg and diastolic by up to 3 mmHg, peaking 2 to 4 hours later, and it usually settled within 12 hours [1]. The label warns that doses taken close together may add to that effect.
Where 1.75 mg came from
The dose-finding trial randomized premenopausal women with sexual dysfunction to placebo or 0.75, 1.25 or 1.75 mg, injected as desired for 12 weeks [3]. Efficacy data came from 327 women.
The 1.25 and 1.75 mg groups were pooled for analysis. Against placebo, they gained 0.7 satisfying sexual events a month against 0.2, and their total sexual function score rose 3.6 points against 1.9. Nausea, flushing and headache were the main side effects.
The phase 3 program, called RECONNECT, then used 1.75 mg alone. Two identical trials randomized 1,267 premenopausal women with hypoactive sexual desire disorder to 1.75 mg or placebo, used as needed for 24 weeks [2].
Across both trials, the desire score rose 0.35 points more than on placebo, and distress about low desire fell 0.33 points more, both with P<.001. The desire score runs from 1.2 to 6.0, so the gain was modest on that scale.
What happened at this dose
In the combined phase 3 trials, nausea affected 40.0% on bremelanotide and 1.3% on placebo [4]. Flushing affected 20.3% against 1.3%, and headache 11.3% against 1.9%. Nausea was the most common reason for stopping.
The label adds that nausea needed anti-nausea medicine in 13% of users and ended treatment for 8% [1]. For most, it eased with the second dose. The full record, including skin darkening with daily use, is on bremelanotide side effects.
Who the label rules out
The label rules out bremelanotide for anyone with uncontrolled high blood pressure or known heart disease [1]. It advises checking cardiovascular risk before starting and from time to time during treatment.
It also flags a drug interaction. Bremelanotide can slow the absorption of some pills taken by mouth, and the label singles out naltrexone and indomethacin as the two where the effect mattered.
A dose tested by injection only
Everything above applies to the injection. Bremelanotide was studied as a nasal spray first, at far higher doses, and that route was dropped before approval. Why, and what the nasal studies used, is covered in PT-141 nasal spray.
Among the sellers reviewed on this site, Synergy Rx lists PT-141, and its review covers what the seller publishes about it. Whether the dose fits a particular person is a decision for that person and a prescriber.