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Peptide library

PT-141 (bremelanotide)

Approved drugSexual health & tanning

A melanocortin agonist that increases sexual desire through the brain, not blood flow.

FDA-approved (Vyleesi) for low sexual desire in premenopausal women.

Used for

  • Low libido (women, and used off-label by men)
  • Erectile problems that don’t respond to Viagra-type drugs

How it works

Activates MC3/MC4 receptors in the hypothalamus, pathways that drive sexual desire and arousal.

Half-life: about 2.7 hours

What the research shows

  • Two phase 3 trials (RECONNECT): 1.75 mg as needed improved desire and reduced distress over 24 weeks.
Sources
Kingsberg 2019, Obstet Gynecol (RECONNECT) Dhillon 2019, Drugs (approval summary)

Dosing

Dosing isn’t listed on the public site. In the app, each published option is shown with its source (a drug label, a clinical guideline, a trial or community reports) and can be turned into a protocol you review.

Work out the units to draw for your vial →

Side effects

  • Nausea (about 40% in trials)
  • Flushing, headache
  • Temporary rise in blood pressure
  • Darkening of gums, face or breasts with repeat use

Cautions

  • Avoid with uncontrolled high blood pressure or heart disease.
  • Delays absorption of naltrexone and some other oral drugs.

Storage

Prescribing label

Unmixed or unopened: At or below 25 °C. Do not freeze; protect from light.

From the Vyleesi (Cosette) label.

Stability once mixed

Built to be stableEstimated from structure, not tested

A ring-shaped (cyclic) peptide, which usually resists breakdown. The approved autoinjector is kept at or below 25 °C, but that is a ready-made injector, not a vial you mix.

Heat, shaking, freezing a mixed vial, light and many needle punctures all speed breakdown. Toss it if it turns cloudy, grows specks or changes color.

Interactions

It can sharply lower the level of oral naltrexone (for alcohol or opioid addiction); the label says to avoid the two together.

Prescribing labelVyleesi label, section 7.2

It slows stomach emptying: avoid it when you take pills that must reach a certain level to work (antibiotics are the label’s example).

Prescribing labelVyleesi label, section 7.1

Not a full list. Tell your doctor and pharmacist everything you take.

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Reference only, not medical advice. Written for this app from the cited research. Doses marked community-reported are not from trials.