LA LABResearch Reference Document
Compound Guide
PT-141 — Bremelanotide (Vyleesi)
Quick Start
FDA Approved — Women with HSDD Only
Bremelanotide (Vyleesi) was FDA approved on June 21, 2019 for premenopausal women with acquired, generalised Hypoactive Sexual Desire Disorder (HSDD). The FDA label specifies this indication only. Use in men, postmenopausal women, or any other context is investigational. For research purposes, all uses outside the approved label are investigational.
What It Is
PT-141 (Bremelanotide) is a synthetic cyclic heptapeptide melanocortin receptor agonist derived from Melanotan II. Unlike MT-II, PT-141 has minimal tanning effect. It was approved as Vyleesi by Palatin Technologies for HSDD — the first centrally acting drug for female sexual dysfunction. It acts in the brain, not on genitalia.
Approved Dosing (Vyleesi)
1.75 mg SubQ, administered at least 45 minutes before anticipated sexual activity. Maximum one dose per 24 hours; maximum 8 doses per month. Do not take with alcohol. Inject in abdomen or thigh. Auto-injector device (Vyleesi) or research vial reconstitution for investigational use.
Regulatory Status
FDA approved (Vyleesi) June 21, 2019. Approved indication: premenopausal women with acquired generalised HSDD. Not approved for: men, postmenopausal women, or any other indication. No WADA ban. For research purposes only in non-approved contexts.
Dosing Protocol
| Context | Dose | Timing | Limits |
|---|---|---|---|
| Vyleesi (approved) | 1.75 mg | ≥45 min before activity | Max 1/24h; max 8/month |
| Research (investigational) | 1.0–1.75 mg | ≥45 min before activity | Same frequency limits apply in research protocols |
Do NOT Combine with Melanotan II
PT-141 and Melanotan II both act on melanocortin receptors (MC1R, MC3R, MC4R). Combining them risks additive melanocortin side effects including significant nausea, vomiting, facial flushing, and blood pressure elevation. They should not be used together.
Supplies & Reconstitution (Research Vials)
Reconstitution Math — 10 mg Vial (3 mL BAC)
| Target Dose | Units (U-100) | Doses / Vial |
|---|---|---|
| 0.5 mg | 15.0 units | 20 |
| 1 mg | 30.0 units | 10 |
| 1.5 mg | 45.0 units | 6.7 |
| 2 mg | 60.0 units | 5 |
Reconstitute the 10 mg vial with 3.0 mL bacteriostatic water (sold separately) → 3.33 mg/mL. U-100 syringe = 100 units per mL. Swirl gently — do not shake. Refrigerate 2–8°C.
Reconstitution Steps
01
Warm the vial
Allow lyophilised vial to reach room temperature before reconstitution.
02
Swab and draw
Alcohol swab both vial tops, air-dry. Draw 3.0 mL BAC water.
03
Inject along the wall
Let BAC water run slowly down the inside wall. Do not jet onto the powder.
04
Swirl gently
Swirl until clear. Do not shake. Solution should be clear to light yellow.
05
Refrigerate
Store at 2–8°C for up to 30 days. Protect from light. Do not freeze after reconstitution.
Mechanism of Action
MC3R / MC4R Agonism (Brain)
Activates MC3R and MC4R melanocortin receptors in the paraventricular nucleus (PVN) of the hypothalamus and other limbic regions. These receptors modulate sexual response and reward circuits — the mechanism is central, not peripheral.
Oxytocin Pathway
MC4R activation in the PVN stimulates oxytocin neurons, which project to limbic and spinal circuits involved in arousal and sexual response. Proposed as a key downstream mediator of PT-141's mechanism of action.
No Direct Genital Effect
Unlike PDE5 inhibitors (sildenafil, tadalafil) which act on genital vasculature, PT-141 acts centrally in the brain. Effect onset is not linked to manual stimulation. Approved for use ≥45 min before anticipated activity — not acutely on demand like PDE5i.
Blood Pressure Effects
Can cause transient blood pressure elevation (mean +6.1 mmHg systolic, 3.8 mmHg diastolic in Phase 3). This is an approved label warning and contraindicates use with antihypertensives or cardiovascular disease in clinical contexts.
Key Research
| Study | Design | Key Finding |
|---|---|---|
| RECONNECT 1 (Kingsberg 2019) | Phase 3 RCT; premenopausal women with HSDD; n=~600; 24 weeks | Significant improvement in desire score and distress vs placebo; nausea most common AE (40%) |
| RECONNECT 2 (Kingsberg 2019) | Phase 3 RCT; same design; n=~600; 24 weeks | Confirmed RECONNECT 1 findings; formed FDA approval basis |
| Combined RECONNECT meta | n=~1,200 women | ~0.5 additional satisfying sexual events/month; statistically significant |
Storage
| State | Temperature | Duration | Notes |
|---|---|---|---|
| Lyophilised (powder) | −20°C (freezer) | Up to 24 months | Protect from light and moisture |
| Reconstituted (liquid) | 2–8°C (refrigerator) | Up to 30 days | Do not freeze after reconstitution; protect from light |
Disclaimer
This document is an educational research reference only. Bremelanotide (Vyleesi) is FDA-approved only for premenopausal women with acquired generalised HSDD. All other uses are investigational. Do not combine with Melanotan II. By purchasing from LA LAB you confirm you are 18+ and that products are for research purposes only.
Side Effects & Clinical Trial Incidence
PT-141 is FDA-approved as bremelanotide (Vyleesi) for hypoactive sexual desire disorder in premenopausal women, so these figures come from proper trials rather than user reports.
| Reported in trials | Incidence |
|---|---|
| Nausea | About 40% — by far the most common, and the main reason people stop. Often worst on the first dose. |
| Flushing | Around 20%. |
| Injection-site reactions | Around 13%. |
| Headache | Around 11%. |
| Vomiting | Around 5%. |
| Darkening of skin (hyperpigmentation) | Reported with repeated use — PT-141 acts on melanocortin receptors, the same family that drives pigmentation. May not fully reverse. |
Nausea is the defining side effect
Four in ten people in the trials felt sick. It is dose-related, and it is why the licensed product is limited to no more than one dose in 24 hours and no more than eight a month. Taking more does not work better; it just makes you more nauseous.
Who Should Avoid PT-141
| Situation | Why |
|---|---|
| Uncontrolled high blood pressure | Contraindicated on the label. PT-141 causes a transient rise in blood pressure and a fall in heart rate. |
| Known cardiovascular disease | Contraindicated on the label. |
| Pregnancy or breastfeeding | Avoid. |
| Taking naltrexone by mouth | PT-141 can significantly reduce naltrexone levels — a documented interaction. |
| Many moles, or a history of skin cancer | Melanocortin activity affects pigmentation. Have any changing mole checked. |
| Under 18 | Not indicated. |
Frequently Asked Questions
How is it different from Viagra?
Completely. Sildenafil works on blood flow; PT-141 works in the brain on melanocortin receptors and acts on desire rather than mechanics. That is why it was approved for a desire disorder.
Completely. Sildenafil works on blood flow; PT-141 works in the brain on melanocortin receptors and acts on desire rather than mechanics. That is why it was approved for a desire disorder.
How long before it works?
The licensed guidance is at least 45 minutes before anticipated activity. Effects are described as lasting hours.
The licensed guidance is at least 45 minutes before anticipated activity. Effects are described as lasting hours.
Can I use it with sildenafil or tadalafil?
Different mechanisms, and people do — but both affect blood pressure. Not something to combine without a prescriber if you have any cardiovascular history.
Different mechanisms, and people do — but both affect blood pressure. Not something to combine without a prescriber if you have any cardiovascular history.
Will it tan my skin?
Possibly with repeated use. That is the same receptor family Melanotan works through, and the pigmentation may not fully reverse.
Possibly with repeated use. That is the same receptor family Melanotan works through, and the pigmentation may not fully reverse.
How do I avoid the nausea?
Start low. The nausea is dose-related, and many users find a lower dose gives most of the effect with much less of it.
Start low. The nausea is dose-related, and many users find a lower dose gives most of the effect with much less of it.
How often can I use it?
The licensed limits are one dose in 24 hours and eight per month.
The licensed limits are one dose in 24 hours and eight per month.
Sources & Research
Kingsberg SA et al. Bremelanotide for the Treatment of Hypoactive Sexual Desire Disorder: Two Randomized Phase 3 Trials. Obstet Gynecol 2019;134:899–908.
Clayton AH et al. Bremelanotide for female sexual dysfunctions in premenopausal women: a randomized, placebo-controlled dose-finding trial. Womens Health 2016;12:325–37.
Prescribing information — Vyleesi (bremelanotide injection), including contraindications, dosing limits and the naltrexone interaction.
Regulatory status — FDA-approved for HSDD in premenopausal women. Not approved by SAHPRA for supply in this form.
Educational reference only
This document is a research reference, not medical advice and not a treatment plan. PT-141 is approved for one specific indication in premenopausal women, and not by SAHPRA for supply in this form. Dose decisions belong to you and your prescriber. Independent certificates of analysis for every LA LAB batch are published under Research → Lab Results, with the Janoshik task number and verification key so you can check them yourself.