Overview
PT-141, also known as bremelanotide, is a melanocortin receptor agonist that works centrally via MC4R activation to influence sexual desire pathways. The FDA-approved formulation is intended for managing hypoactive sexual desire disorder (HSDD) in premenopausal women.
Key Specifications
Chemical Classification: Melanocortin-4 receptor (MC4R) agonist
Approved Route: Subcutaneous injection
Standard FDA-Approved Dose: “single 1.75 mg injection as needed (PRN), administered at least 45 minutes before anticipated sexual activity”
Dosing Frequency Limits: Maximum 1 dose per 24 hours; no more than 8 doses per month
Reconstitution Guide
Standard Protocol
– Vial Size: 10 mg powder
– Reconstitution Volume: 3.0 mL bacteriostatic water
– Resulting Concentration: ~3.33 mg/mL
– Measurement Method: U-100 insulin syringes (1 unit = 0.01 mL ≈ 33.3 mcg)
Reconstitution Steps
1. Draw 3.0 mL bacteriostatic water using sterile technique
2. Inject slowly down vial wall; avoid foaming
3. Gently swirl/roll until dissolved (do not shake)
4. Label and refrigerate immediately
Dosing Protocol
| Administration Stage | Dose (mcg) | Dose (mg) | Syringe Units | Volume (mL) |
|---|---|---|---|---|
| Test Dose | 500 | 0.50 | 15 units | 0.15 |
| Titration | 1,000 | 1.00 | 30 units | 0.30 |
| Effective Range | 1,500 | 1.50 | 45 units | 0.45 |
| Standard PRN | 1,750 | 1.75 | 52.5 units | 0.53 |
Timing Considerations
– Administer 45-60 minutes before anticipated sexual activity
– Allow at least 24 hours between doses
– Do not exceed 8 doses per month
– Reassess benefit after approximately 8 weeks of use
Storage Instructions
Lyophilized (Powder): “Cold, dark storage is commonly used for long-term stability (≤ −20 °C / ≤ −4 °F)”
Reconstituted Solution: “Refrigerate at 2–8 °C (35.6–46.4 °F) for short-term holding; avoid repeated freeze–thaw”
Shelf Life: Protect from light and moisture; minimize exposure to humidity
Supplies Needed (Per 8-Week Protocol at 1.75 mg Standard Dose)
– PT-141 Vials: 4 vials (10 mg each)
– U-100 Insulin Syringes: 16 syringes (single-use)
– Bacteriostatic Water: 2 bottles (10 mL each)
– Alcohol Swabs: 32 swabs (vial + injection site)
Note: Each 10 mg vial provides approximately 5 full standard doses
Injection Technique
Site Selection: Abdomen, thighs, or upper arms
Rotation: Systematically rotate sites to reduce local reactions and maintain consistent absorption
Injection Angle: “Insert at 45–90° into subcutaneous tissue; do not aspirate for SC injections”
Technique:
1. Clean vial stopper and skin with alcohol; allow to dry
2. Pinch a skinfold at injection site
3. Insert needle at proper angle; inject slowly and steadily
4. Do not aspirate (SC injection protocol)
Volume Tolerance: “SC injections of up to ~3.0 mL are generally well-tolerated in the abdomen”
Mechanism of Action
PT-141 activates central melanocortin receptors, “especially MC4R—in hypothalamic circuits linked to sexual desire and autonomic arousal.” Two Phase 3 RECONNECT trials demonstrated improvements in validated desire and distress measures compared to placebo using the PRN 1.75 mg subcutaneous dosing regimen.
Clinical Benefits
– Improves sexual desire and reduces related distress in premenopausal women with HSDD
– Phase 3 trial evidence supports efficacy as PRN therapy
– Supports at-home self-administration via subcutaneous delivery
– Modest appetite-suppressive effects noted in mechanistic studies under intensive dosing
Adverse Effects & Warnings
Common Adverse Effects:
– Nausea
– Flushing
– Headache
– Injection-site reactions
– Transient blood pressure increases
– Transient heart rate reductions
Important Safety Notes:
– “Exceeding labeled frequency (e.g., daily use) increased risk of focal hyperpigmentation”
– Consider cardiovascular risk factors before use
– Review full prescribing information for complete precautions
– Use new sterile syringes for each injection
– Follow aseptic preparation and disposal protocols
Lifestyle Considerations
– Communicate timing and expectations with sexual partners
– Coordinate use with anticipated sexual activity
– Support overall wellness through adequate sleep, stress management, and regular exercise
– Maintain consistent injection technique and site rotation
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Last Updated: December 24, 2025
Content Type: Research Educational Material
Classification: For research reference only