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PT-141 (Bremelanotide) protocol

PT-141 (bremelanotide) is an approved US medicine, sold as Vyleesi, for premenopausal women whose low sexual desire causes marked distress.

Approved in the US - Vyleesi (acquired, generalized low desire in premenopausal women)US label: not for men, not for postmenopausal women, and not to improve performance
ProtocolMixingResultsSide effectsHow it worksSources

The protocol at a glance

The US label dose is a single 1.75 mg injection under the skin of the belly or thigh, at least 45 minutes before sex. Use no more than once in 24 hours and no more than 8 doses a month.

ItemUS label
Amount per dose1.75 mg under the skin (belly or thigh), autoinjector
TimingAt least 45 minutes before expected sexual activity
Most often1 dose in 24 hours
Per monthMore than 8 doses is not recommended
If no helpStop after 8 weeks

From the Vyleesi US prescribing information (DailyMed). The product is a ready-made single-use autoinjector (1.75 mg in 0.3 mL). The calculator shows vial maths only for a 10 mg vial and is not a label instruction.

Community reports

Community reports commonly describe 1-2 mg injections, often from vials.

What people say they do, collected from community discussions. Not tested in a trial; shown so you can compare it with the evidence above.

Mixing calculator

Enter the vial size, the water you add and the amount you want to draw; it gives the mark on a 100-unit (1 mL) insulin syringe.

Draw to – units

What the trials found

Two identical 24-week placebo-controlled trials (RECONNECT), about 600 women each. Measured: change in sexual desire score (FSFI-Desire):

+0.5Vyleesi, study 1
+0.2Placebo, study 1
+0.6Vyleesi, study 2
+0.2Placebo, study 2

Vyleesi US prescribing information. Distress about low desire also fell more with Vyleesi (-0.7 vs -0.4 in both studies). The label notes no significant difference in satisfying sexual events. Simon JA et al. Obstet Gynecol 2019 (PMID 31599847) covers the 52-week extension.

Side effects

  • Nausea 40% (vs 1.3% placebo), flushing 20%, injection site reactions 13%, headache 11%, vomiting 4.8%.
  • Side effects made 18% of Vyleesi users stop vs 2% on placebo.
  • Each dose briefly raises blood pressure (about 6/3 mmHg) for up to 12 hours. It is not for uncontrolled high blood pressure or known heart disease.
  • Dark skin patches (face, gums, breasts) occurred in about 1% in the main trials and in 38% of people given daily doses for 8 days. They did not always go away.

How it works

Melanocortin receptors

It switches on several melanocortin receptors; MC1R and MC4R matter most at label doses. How it raises desire is not known.

Sources

  • VYLEESI (bremelanotide) US prescribing information, DailyMed setid f1d0c1b5-2f39-4bad-a6a4-0066e3ad5dcf
  • Simon JA et al. Obstet Gynecol 2019 (RECONNECT extension), PMID 31599847
  • ClinicalTrials.gov NCT02333071 and NCT02338960 (RECONNECT)