PT-141 (Bremelanotide)
MC3R/MC4R agonist — approved in the US as Vyleesi
Experimental material. Read before using anything from here.
Nothing on this page is a medical recommendation, prescription or treatment plan. It is an organized translation of protocols circulating in research communities and, where it exists, of what published trials tested. The two are marked differently — and they are not equivalent.
Most of the compounds here have no FDA approval for human use. Several are sold labeled "research use only", which means they have not gone through purity, sterility or dosage controls for human consumption. A community-reported dose is not a validated dose: it is what someone reported having done.
Talk to a licensed health professional before considering any of these compounds. If you already use one and feel anything unexpected, seek care — do not wait for the next routine test.
Summary
Synthetic cyclic peptide that activates two melanocortin receptors in the brain, MC3R and MC4R. It is the active ingredient of Vyleesi, an FDA-approved injection for hypoactive sexual desire in premenopausal women. Outside that indication, use is off-label and the schedules come from the community.
Quick reference
- Approved route
- Subcutaneous (Vyleesi autoinjector). Intranasal is investigational and compounded.
- Approved dose
- 1.75 mg SC, ≥45 min before sexual activity, per the package insert.
- Approved frequency
- At most 1 dose per 24 h and 8 doses per month.
- Approved population
- Premenopausal women with acquired, generalized HSDD.
PT-141 Protocol Formats
| Parameter | Value | Source |
|---|---|---|
| Dose | 1.75 mg | Vyleesi label / Mayo Clinic drug summary |
| Route | Subcutaneous (abdomen or thigh) | Vyleesi label |
| Timing | ≥45 minutes before sexual activity | Vyleesi label |
| Maximum frequency | 1 dose per 24 hours | Vyleesi label |
| Maximum monthly use | 8 doses per month | Vyleesi label |
| Approved population | Premenopausal women with HSDD | Vyleesi label |
Cycle Guidelines
| Approach | Pattern | Reference Source |
|---|---|---|
| FDA-approved on-demand (Vyleesi) | 1.75 mg subQ ≥45 min before activity, ≤1/24h, ≤8/month | Vyleesi label (Mayo Clinic summary) |
| Phase 3 trial schedule | 1.75 mg subQ on demand for 24 weeks | Kingsberg 2019 (RECONNECT) |
| Long-term safety extension | 1.75 mg subQ on demand for an additional 52 weeks | Simon 2019 (open-label extension) |
| Phase 2 intranasal (men with ED) | 7.5-20 mg intranasal in trial arms studied | Diamond 2006 |
PT-141 Reconstitution Guide
| BAC water added | Final concentration | 0.10 mL draw delivers | Volume to deliver 1.75 mg |
|---|---|---|---|
| 1 mL | 10 mg/mL | 1.0 mg | 0.175 mL (~17.5 units on a U-100 syringe) |
| 2 mL | 5 mg/mL | 0.5 mg | 0.35 mL (~35 units on a U-100 syringe) |
| 2.5 mL | 4 mg/mL | 0.4 mg | 0.4375 mL (~43.75 units on a U-100 syringe) |
PT-141 Timeline & What to Monitor
| Time after subQ dose | What was reported | Source context |
|---|---|---|
| 0-30 minutes | Possible flushing; nausea may begin | Vyleesi label / RECONNECT trial reports |
| 30-60 minutes | Pharmacodynamic effects begin | Phase 3 trial protocol design |
| 1-3 hours | Reported peak effect window | Trial-reported timing |
| 4-12 hours | Effects taper; nausea typically resolves within hours | Vyleesi label |
Storage and handling
The rules below apply to practically every lyophilized peptide in this reference. Where a compound has its own requirement, it appears in the table in the previous section.
- Lyophilized powder, sealed: refrigerator, between 2 and 8 °C, protected from light. Many tolerate room temperature for short transport periods, but that is tolerance, not a recommendation.
- After reconstitution: always refrigerated, between 2 and 8 °C. The stability window drops to days or a few weeks, depending on the compound.
- Never freeze after reconstituting. The freeze–thaw cycle degrades the peptide.
- Do not shake. Swirl the vial slowly. Shaking breaks the peptide chain.
- Bacteriostatic water down the wall of the vial, in a slow stream, not squirted directly onto the powder.
- Cloudy solution, with particles or a color change: discard. There is no recovery.
Lab tests and monitoring
This list is the one that appears recurrently in the source, with small variations by compound. It serves as a starting point for a conversation with a professional — not as a substitute for that conversation.
- Before starting: complete blood count, comprehensive metabolic panel, lipid panel, fasting glucose and HbA1c, TSH and free T4, blood pressure and resting heart rate.
- Depending on the compound: IGF-1 (GH axis), lipase and amylase (VIP and the incretin agonists), serum copper and ceruloplasmin (GHK-Cu and blends containing it), CRP.
- Reassessment: most protocols review between week 4 and week 8, and then every 8–12 weeks.
- Do not wait for the routine lab test in the face of abdominal pain, visual changes, a change in a mole, shortness of breath, asymmetric swelling or any new and persistent symptom. That is a reason to seek care, not a spreadsheet item.
Evidence limits
Data source: peptidedosingprotocols.com, accessed on September 3, 2026. Translation and organization in Portuguese are original work. No primary source (PubMed, trial registry, package insert) was checked in building this page — the check was against the secondary source, and that alone.