PT-141 (Bremelanotide)
Bremelanotide · Vyleesi
FDA-approved (2019) for premenopausal hypoactive sexual desire disorder
Overview
PT-141, known generically as bremelanotide and marketed as Vyleesi, is a cyclic heptapeptide melanocortin-receptor agonist. Unlike phosphodiesterase inhibitors that act on vascular smooth muscle, it works centrally on melanocortin receptors in the nervous system, which is why it is studied for desire rather than purely for erectile mechanics.
It received U.S. FDA approval in 2019 for the treatment of acquired, generalized hypoactive sexual desire disorder (HSDD) in premenopausal women, administered as a single 1.75 mg subcutaneous injection taken on an as-needed basis at least 45 minutes before anticipated activity, with use limited to no more than one dose in 24 hours and eight doses per month.
Approval was supported by the two pivotal RECONNECT Phase 3 trials, which reported statistically significant improvements in desire and in distress associated with low desire versus placebo. Nausea was the most common adverse effect, and a transient rise in blood pressure with a corresponding fall in heart rate has been described after dosing. Figures below summarize the label and published trials for research reference only.
Key parameters
- Dose range
- 1.75 mg per dose (approved)
- Frequency
- As needed (≤8/month)
- Half-life
- ~2.7 hours (range 1.9–4.0 h)
- Route
- Subcutaneous
- Vial sizes
- 10 mg
- Regulatory status
- FDA-approved (Vyleesi) for premenopausal HSDD; research-vial material is laboratory use only.
Mechanism of action
Melanocortin-4 receptor (MC4R) agonism
Activates MC4R (with activity at other melanocortin receptors) in central nervous system pathways implicated in sexual desire and arousal, producing a centrally mediated effect distinct from vascular-acting agents.
Central (non-vascular) site of action
Acts on brain circuitry rather than directly on genital vasculature, which is the basis for its use in disorders of desire as opposed to purely mechanical dysfunction.
Dosing protocol & phases
| Phase | Weeks | Dose | Notes |
|---|---|---|---|
| As-needed use | On demand | 1.75 mg subcutaneously | Administer at least 45 minutes before anticipated activity; no more than one dose per 24 hours. |
| Monthly ceiling | Per month | ≤8 doses | Per the Vyleesi label; discontinue after 8 weeks if no improvement in symptoms. |
Reconstitution guide
For educational and research reference only. Not intended for human consumption, not medical advice. Compounds discussed are sold and used for laboratory research purposes only.
10 mg vial + 2 mL bacteriostatic water
Concentration5,000 mcg/mL · 5 mg/mL
| Target dose | Draw volume | U-100 units |
|---|---|---|
| 1,000 mcg | 0.2 mL | 20 |
| 1,750 mcg | 0.35 mL | 35 |
| 2,000 mcg | 0.4 mL | 40 |
Common mix; the 1.75 mg dose draws to 0.35 mL (35 units on a U-100 syringe).
10 mg vial + 1 mL bacteriostatic water
Concentration10,000 mcg/mL · 10 mg/mL
| Target dose | Draw volume | U-100 units |
|---|---|---|
| 1,000 mcg | 0.1 mL | 10 |
| 1,750 mcg | 0.175 mL | 17.5 |
| 2,000 mcg | 0.2 mL | 20 |
Higher-strength mix that keeps the 1.75 mg dose to a small 0.175 mL draw.
Reconstitution calculator
Pre-filled with PT-141 (Bremelanotide)'s vial sizes. Adjust the water volume and target dose to see the exact draw, with warnings for doses that are hard to measure or won't fit a syringe.
At 5,000 micrograms per millilitre, a 1,000 microgram dose is 0.2 millilitres, or 20 units on a U-100 syringe, giving 10 doses per vial.
Supplies needed
Affiliate disclosure: we may earn a commission from supplier links, at no extra cost to you. For research and educational use only.
Recommended supply
PT-141 (Bremelanotide) — research vial
From our verified partner Dynotides, with a third-party certificate of analysis per batch.
Injection supplies
- View
Bacteriostatic water
Diluent for reconstituting lyophilized vials.
- Buy
Insulin syringes (U-100)
0.3–0.5 mL, 29–31 G for accurate small draws.
- Buy
Alcohol prep pads
Sterile swabs for the vial stopper and site.
- Buy
Sharps container
Safe disposal of used needles.
- Buy
Storage fridge
Keeps reconstituted vials at 2–8 °C.
- Buy
Insulated travel case
Cooled, TSA-friendly case for travel.
Missed-dose guidance
PT-141 is used on an as-needed basis rather than on a fixed schedule, so there is no 'missed dose' to make up. Do not take more than one dose within any 24-hour period and do not exceed eight doses per month.
Side effects & safety
| Category | Effect | Trial incidence |
|---|---|---|
| Gastrointestinal | NauseaMost common adverse effect (Vyleesi label); median onset ~30 min, median duration ~2.4 h. Required anti-emetics in ~13% and led to discontinuation in ~8%. | 40% |
| Dermatologic | FlushingReported as 20.3% in pooled Phase 3 data. | 20% |
| Neurological | HeadacheReported as 11.3% in pooled Phase 3 data. | 11% |
| Injection site | Injection-site reactions~5.4% in pooled Phase 3 data. | 5% |
| Gastrointestinal | Vomiting~4.8% in pooled Phase 3 data. | 5% |
| Cardiovascular | Transient blood-pressure increase / heart-rate decreaseDescribed post-dose; contraindicated in uncontrolled hypertension or known cardiovascular disease. | — |
| Dermatologic | Focal hyperpigmentationReported with repeated melanocortin-agonist dosing. | — |
Clinical trials & evidence
RECONNECT (Study 301)
Phase 324 weeks (core) · Premenopausal women with acquired, generalized HSDD
Significant improvement vs placebo in desire and in distress related to low desire (co-primary endpoints).
NCT02333071 ↗RECONNECT (Study 302)
Phase 324 weeks (core) · Premenopausal women with acquired, generalized HSDD
Replicated significant improvement vs placebo on the co-primary desire and distress endpoints.
NCT02338960 ↗
Storage & handling
- Lyophilized
- Store lyophilized powder refrigerated at 2–8 °C, protected from light.
- Reconstituted
- Refrigerate reconstituted solution at 2–8 °C and use within ~28 days. Do not freeze.
Comparisons
| Vs. | Target | Half-life | Dosing | Efficacy | Status |
|---|---|---|---|---|---|
| Melanotan II | MC4R-focused (cyclic heptapeptide) vs broad melanocortin agonist | ~2.7 h vs ~1–2 h | 1.75 mg as needed vs community-dependent | Approved for HSDD vs not established | FDA-approved vs not approved |
| Kisspeptin | Melanocortin (MC4R) vs KISS1R (upstream of GnRH) | ~2.7 h vs minutes | 1.75 mg per dose vs pulse/infusion | Approved for HSDD vs investigational | FDA-approved vs investigational |
Sources & references
Frequently asked questions
How is PT-141 different from PDE5 inhibitors?
PDE5 inhibitors act on vascular smooth muscle to improve blood flow. PT-141 (bremelanotide) acts centrally on melanocortin receptors in the nervous system, which is why it is studied and approved for low sexual desire rather than purely for mechanical function.
What is Vyleesi approved for?
Vyleesi (bremelanotide) is FDA-approved for acquired, generalized hypoactive sexual desire disorder (HSDD) in premenopausal women, given as a 1.75 mg subcutaneous injection on an as-needed basis.
Are there limits on how often it can be used?
Per the label, no more than one dose in 24 hours and no more than eight doses per month. It is also typically discontinued if there is no symptom improvement after about eight weeks.
Related protocols
Melanotan II
MT-II
Non-selective melanocortin agonist (tanning + libido); the precursor context for PT-141
Kisspeptin
Kisspeptin-10
+56% penile rigidity vs placebo in men with HSDD (Comninos/Dhillo, 2023)
Oxytocin
OXT
Endogenous bonding nonapeptide; large autism trial (SOARS-B) found no benefit over placebo
Looking to match this protocol to a verified research vial? Our partner supplier publishes a certificate of analysis per batch.
For educational and research reference only. Not intended for human consumption, not medical advice. Compounds discussed are sold and used for laboratory research purposes only.