Primus Anabolics

PT-141

The peptide for sexual dysfunction

PT-141
07 Apr 2026

Quickstart – key points

PT-141 (bremelanotide) is a synthetic cyclic heptapeptide and non-selective agonist of melanocortin receptors (MC3R/MC4R), derived as an active metabolite of Melanotan II.

It was approved in 2019 for hypoactive sexual desire disorder in premenopausal women.

Bremelanotide increases sexual desire by activating the MC4R receptor in the brain’s reward and arousal pathways, increasing dopamine release in key brain areas.

This educational protocol presents a daily subcutaneous approach with gradual titration and a practical dilution for precise measurements with an insulin syringe.

  • Reconstitution: Add 3.0 mL of bacteriostatic water → approximate concentration of 3.33 mg/mL.
  • Typical daily range: 500–1500 mcg once daily (progressive titration up to 16 weeks).
  • Easy measurement: At 3.33 mg/mL, 1 unit = 0.01 mL ≈ 33.3 mcg on a U-100 syringe.
  • Storage: Lyophilized: freeze at −20 °C; after reconstitution, refrigerate at 2–8 °C; avoid freeze-thaw cycles.

Dosage and Reconstitution Guide

Educational guide for reconstitution and daily dosing.

Standard / gradual approach (3 mL = ~3.33 mg/mL)

  • Weeks 1–8: 500 mcg (0.5 mg) → 15 units (0.15 mL)

  • Weeks 9–12: 1000 mcg (1.0 mg) → 30 units (0.30 mL)

  • Weeks 13–16: 1500 mcg (1.5 mg) → 45 units (0.45 mL)

  • Frequency and route: Subcutaneous injection once daily (abdomen or thigh). The subcutaneous route provides high bioavailability and better tolerance than the intranasal route. There is also an approved “on demand” use of 1.75 mg before sexual activity, but this protocol follows a more conservative daily progression.

Reconstitution Steps

  1. Draw 3.0 mL of bacteriostatic water with a sterile syringe.
  2. Inject slowly down the side of the vial; avoid foaming.
  3. Gently swirl until dissolved (do not shake).
  4. Label and refrigerate at 2–8 °C, protected from light.

Important: This guide is educational only and does not constitute medical advice. For research use only. Not for human consumption.

Required Supplies

Plan based on a daily 8–16 week protocol with gradual titration.

  • Peptide vials (PT-141, 10 mg):
    • 8 weeks ≈ 3 vials
    • 12 weeks ≈ 6 vials
    • 16 weeks ≈ 10 vials
  • Insulin syringes (U-100):
    • Per week: 7
    • 8 weeks: 56
    • 12 weeks: 84
    • 16 weeks: 112
  • Bacteriostatic water (10 mL):
    • 8 weeks: 9 mL → 1 bottle
    • 12 weeks: 18 mL → 2 bottles
    • 16 weeks: 30 mL → 3 bottles
  • Alcohol wipes:
    • Per week: 14
    • 8 weeks: 112 → recommend 2 boxes
    • 12 weeks: 168 → recommend 2 boxes
    • 16 weeks: 224 → recommend 3 boxes

Protocol Summary

  • Objective: Increase sexual desire and arousal through activation of melanocortin receptors in the central nervous system.
  • Duration: 8–12 weeks (optional up to 16 weeks).
  • Dose range: 500–1500 mcg daily with gradual titration.
  • Reconstitution: 3.0 mL per 10 mg vial (~3.33 mg/mL).
  • Storage: Lyophilized frozen; reconstituted refrigerated; avoid repeated freezing.

Dosing Protocol

  • Start: 500 mcg daily for the first 8 weeks.
  • Escalation: 1000 mcg daily in weeks 9–12.
  • Goal: 1500 mcg daily in weeks 13–16 if well tolerated.
  • Frequency: Once daily (subcutaneous).
  • Schedule: Maintain consistent schedule; rotate injection sites.

Storage Instructions

  • Lyophilized: −20 °C in a dry and dark environment.
  • Reconstituted: 2–8 °C; use within ~30 days; avoid freezing.
  • Let the vial reach room temperature before opening to avoid condensation.

Important Notes

  • Use new sterile syringes for every injection.
  • Rotate sites (abdomen, thighs) to avoid irritation.
  • Inject slowly and wait before removing the needle.
  • Record dose and injection sites.
  • The most common side effect is nausea, usually mild and temporary; flushing or headache may also occur.

How it works

Bremelanotide is an analog of the melanocyte-stimulating hormone that acts as an agonist of melanocortin receptors, primarily MC3R and MC4R. In the central nervous system, MC4R activation increases dopamine release in areas related to reward and arousal, which increases sexual desire.

Unlike PDE5 inhibitors, it does not act directly on blood flow, but at a central level. Some side effects, such as increased blood pressure or darkening of the skin, are related to the activation of other peripheral receptors.

Potential Benefits and Side Effects

  • Increased sexual desire and arousal.
  • Improvement of sexual response in some cases.
  • Possible benefits also in men according to initial studies.
  • Common side effects: nausea, flushing, headache.
  • Possible temporary increase in blood pressure.
  • Possible darkening of the skin with prolonged use.

Lifestyle Factors

  • Maintain balanced diet and regular exercise.
  • Sleep well (key for libido and hormones).
  • Reduce stress (directly affects sexual desire).
  • Limit alcohol.

Injection Technique

  • Clean vial and skin with alcohol.
  • Pinch the skin and insert the needle at 45–90°.
  • Do not aspirate; inject slowly.
  • Rotate sites (abdomen, thighs).
  • Dispose of syringe after use.