PT-141 / Bremelanotide BAC Water & Reconstitution Guide
PT-141, also known as bremelanotide, is a synthetic melanocortin receptor agonist. Unlike many investigational peptides, bremelanotide has an FDA-approved prescription product, Vyleesi, for acquired, generalized hypoactive sexual desire disorder in premenopausal women. The FDA-approved product is supplied as a 1.75 mg/0.3 mL single-dose injection rather than as a powder requiring BAC-water reconstitution.
How Much BAC Water for PT-141 / Bremelanotide?
There is no universal BAC-water volume for every PT-141 or bremelanotide preparation. The FDA-approved Vyleesi product is already supplied as a sterile 1.75 mg/0.3 mL solution and is not labeled as a powder requiring reconstitution. Therefore, the concentration examples below are mathematical research examples rather than instructions to reconstitute Vyleesi.
Do not assume that an FDA-approved liquid formulation can be treated like a lyophilized research vial. The FDA label identifies Vyleesi as a 1.75 mg/0.3 mL solution supplied in a single-dose autoinjector.
| Hypothetical Quantity | 1 mL | 2 mL | 2.5 mL | 3 mL | 5 mL |
|---|---|---|---|---|---|
| 5 mg | 5 mg/mL | 2.5 mg/mL | 2 mg/mL | 1.67 mg/mL | 1 mg/mL |
| 10 mg | 10 mg/mL | 5 mg/mL | 4 mg/mL | 3.33 mg/mL | 2 mg/mL |
| 20 mg | 20 mg/mL | 10 mg/mL | 8 mg/mL | 6.67 mg/mL | 4 mg/mL |
Need a different vial quantity or BAC-water volume?
Use the BacScience Universal BAC Water Calculator for custom concentration mathematics.
How Much BAC Water Should Be Added to PT-141?
There is no single BAC-water volume that applies to every PT-141/bremelanotide preparation. More importantly, the FDA-approved Vyleesi product is already supplied as a 1.75 mg/0.3 mL solution, so the FDA-approved product is not labeled for reconstitution with BAC water. :contentReference[oaicite:2]{index=2}
For a separate hypothetical research preparation, concentration can be calculated mathematically by dividing the total peptide quantity by the liquid volume. For example, 10 mg represented in 2 mL would correspond mathematically to 5 mg/mL.
A concentration such as 5 mg/mL describes the amount of compound represented per milliliter. It does not tell a person how much should be administered or establish a safe treatment regimen.
How much BAC water for PT-141 5 mg?
If a hypothetical 5 mg quantity were represented in different liquid volumes, the mathematical concentrations would be:
- 5 mg ÷ 1 mL = 5 mg/mL
- 5 mg ÷ 2 mL = 2.5 mg/mL
- 5 mg ÷ 2.5 mL = 2 mg/mL
- 5 mg ÷ 5 mL = 1 mg/mL
These are mathematical examples, not PT-141 administration instructions.
How much BAC water for PT-141 10 mg?
For a hypothetical 10 mg quantity:
- 10 mg ÷ 1 mL = 10 mg/mL
- 10 mg ÷ 2 mL = 5 mg/mL
- 10 mg ÷ 2.5 mL = 4 mg/mL
- 10 mg ÷ 3 mL = 3.33 mg/mL
- 10 mg ÷ 5 mL = 2 mg/mL
How does BAC-water volume change PT-141 concentration?
When the total peptide quantity remains constant, increasing the liquid volume decreases concentration. Decreasing liquid volume increases concentration.
The underlying mathematical relationship is:
What Is PT-141 / Bremelanotide?
Bremelanotide, historically known as PT-141, is a synthetic peptide analog of alpha-melanocyte-stimulating hormone (α-MSH) and a melanocortin receptor agonist. FDA materials describe bremelanotide as acting on melanocortin receptors including MC1, MC3, MC4 and MC5. :contentReference[oaicite:3]{index=3}
Bremelanotide was developed for disorders involving sexual desire and arousal. Its regulatory history is distinct from many compounds described as “research peptides”: the FDA approved Vyleesi (bremelanotide injection) in 2019 for a specific population of premenopausal women with acquired, generalized hypoactive sexual desire disorder (HSDD). :contentReference[oaicite:4]{index=4}
The approval applies to the specific prescription product, formulation, route, indication and labeling. A separately manufactured or compounded research preparation should not be represented as equivalent to Vyleesi.
How Bremelanotide Works
Bremelanotide activates melanocortin receptors. The melanocortin system participates in several physiological processes, including sexual behavior, feeding and energy regulation.
The FDA-approved therapeutic mechanism is therefore different from simply treating a local sexual-function problem: bremelanotide acts through central melanocortin signaling.
What Is Bremelanotide Being Studied / Used For?
Vyleesi is indicated for acquired, generalized HSDD in premenopausal women when the condition causes marked distress or interpersonal difficulty and is not attributable to another medical or psychiatric condition, relationship problems, or a medication or drug substance.
The FDA label specifically states that Vyleesi is not indicated for HSDD in postmenopausal women or men and is not indicated to enhance sexual performance. :contentReference[oaicite:5]{index=5}
Human Clinical Research
Bremelanotide has been evaluated in multiple controlled clinical trials involving premenopausal women with HSDD and related female sexual dysfunction. The phase 3 RECONNECT program included two randomized, double-blind, placebo-controlled trials involving more than 1,200 women in the safety/efficacy populations. :contentReference[oaicite:6]{index=6}
In those trials, bremelanotide 1.75 mg was administered subcutaneously as needed before sexual activity over 24 weeks. The trials reported statistically significant improvements in measures of sexual desire and distress associated with low desire. :contentReference[oaicite:7]{index=7}
Published clinical evidence for bremelanotide does not establish that an arbitrary powder preparation, concentration, diluent, vial or compounded formulation has the same quality, stability, pharmacokinetics or safety profile as FDA-approved Vyleesi.
Clinical Research Evidence Table
| Study | Population | Dose Studied | Route | Duration | Key Finding |
|---|---|---|---|---|---|
| Dose-finding RCT | Premenopausal women with female sexual dysfunction | 0.75, 1.25 or 1.75 mg | Subcutaneous | 12 weeks | Higher-dose groups showed improvements in sexual-function measures; nausea, flushing and headache were reported. |
| RECONNECT Study 301 | Premenopausal women with HSDD | 1.75 mg | Subcutaneous | 24 weeks | Increased sexual desire and reduced distress compared with placebo. |
| RECONNECT Study 302 | Premenopausal women with HSDD | 1.75 mg | Subcutaneous | 24 weeks | Increased sexual desire and reduced distress compared with placebo. |
| Long-term extension | Women completing RECONNECT | Bremelanotide treatment | Subcutaneous | Up to 52-week extension | No new safety signals were identified during the extension; nausea, flushing and headache remained among common treatment-emergent events. |
These are doses and regimens reported in clinical research or FDA labeling, not BacScience treatment recommendations.
Doses Studied in Published Research
Unlike an investigational peptide with no established clinical product, bremelanotide has a defined FDA-approved product and published clinical dose data.
The FDA labeling specifies 1.75 mg subcutaneously into the abdomen or thigh as needed, at least 45 minutes before anticipated sexual activity. It also states that no more than one dose should be administered within 24 hours and that more than eight doses per month are not recommended. :contentReference[oaicite:8]{index=8}
The FDA-approved dose should not be confused with a mathematical concentration. The FDA-approved Vyleesi product is supplied as 1.75 mg/0.3 mL solution in a single-dose autoinjector. :contentReference[oaicite:9]{index=9}
Important distinction between dose and concentration
- Dose: the amount of active drug administered.
- Concentration: amount of active drug per unit volume, such as mg/mL.
- FDA-approved formulation: the specific manufactured product described in the FDA label.
- Research preparation: a separate preparation whose formulation and quality must not automatically be assumed equivalent to Vyleesi.
Preclinical Research
Bremelanotide was developed from research involving melanocortin biology and analogs of α-MSH. Preclinical studies helped establish activity at melanocortin receptors and supported subsequent clinical development.
Preclinical pharmacology is useful for understanding receptor activity and biological mechanisms, but it should not be used to infer a human dose or treatment protocol when human clinical evidence is available.
Species differences, pharmacokinetics, receptor distribution, metabolism and toxicity can change how a compound behaves in humans.
PT-141 Research Reconstitution & Concentration
For a hypothetical peptide preparation, concentration can be calculated from the quantity of compound and liquid volume.
Concentration Formula
Example:
10 mg ÷ 2 mL = 5 mg/mL
Another example:
10 mg ÷ 5 mL = 2 mg/mL
BAC Water vs. Concentration
When the total amount of peptide is unchanged, adding more liquid produces a lower concentration, while using less liquid produces a higher concentration.
This mathematical relationship should not be interpreted as a recommendation to alter an FDA-approved bremelanotide product.
Worked Mathematical Examples
| Hypothetical Quantity | Liquid Volume | Calculation | Result |
|---|---|---|---|
| 5 mg | 1 mL | 5 ÷ 1 | 5 mg/mL |
| 5 mg | 2 mL | 5 ÷ 2 | 2.5 mg/mL |
| 10 mg | 2 mL | 10 ÷ 2 | 5 mg/mL |
| 10 mg | 5 mL | 10 ÷ 5 | 2 mg/mL |
Research Limitations & Safety
Bremelanotide has an FDA-approved indication, but the approval is specific to Vyleesi and its labeled population, formulation and administration instructions. It is not approval of every PT-141 product or preparation.
FDA-approved indication
Vyleesi is indicated for acquired, generalized HSDD in premenopausal women when the condition is not attributable to another medical or psychiatric condition, relationship problems, or medication/drug effects. It is not indicated for postmenopausal women or men and is not indicated to enhance sexual performance. :contentReference[oaicite:10]{index=10}
Important FDA safety information
- Vyleesi is contraindicated in uncontrolled hypertension and known cardiovascular disease.
- The drug can cause transient increases in blood pressure and decreases in heart rate.
- Nausea is a common adverse reaction.
- Flushing, headache, vomiting and injection-site reactions are also reported adverse reactions.
- Focal hyperpigmentation can occur and may involve the face, gingiva and breasts.
- Vyleesi can slow gastric emptying and can affect absorption of some oral medications.
These points come from the FDA prescribing information and should not be generalized to an unapproved or differently formulated research preparation. :contentReference[oaicite:11]{index=11}
A mathematical calculation cannot establish sterility, stability, compatibility, purity, potency, particulate safety or appropriate administration of a peptide preparation. Those characteristics require appropriate pharmaceutical/manufacturing controls and product-specific evidence.
PT-141 / Bremelanotide BAC Water FAQs
How much BAC water should be added to PT-141?
Is PT-141 the same as bremelanotide?
Is bremelanotide FDA approved?
What is the FDA-approved bremelanotide dose?
What concentration is 10 mg of PT-141 in 2 mL?
Does adding more BAC water reduce PT-141 concentration?
Is Vyleesi supplied as a powder?
What doses of bremelanotide have been studied?
What is the difference between PT-141 concentration and dose?
Can I use the BAC Water Calculator for PT-141?
Is a research PT-141 vial equivalent to Vyleesi?
Where can I calculate another PT-141 concentration?
Scientific References
-
U.S. Food and Drug Administration — Vyleesi Prescribing Information
FDA-approved indication, dosage, formulation, contraindications, warnings and adverse reactions.
View FDA prescribing information -
FDA Approval Package — Vyleesi
Original 2019 approval information for bremelanotide.
View FDA approval package -
Kingsberg et al. — Bremelanotide for the Treatment of Hypoactive Sexual Desire Disorder: Two Randomized Phase 3 Trials
Obstetrics & Gynecology, 2019.
View PubMed record -
Bremelanotide Dose-Finding Randomized Controlled Trial
Evaluation of 0.75, 1.25 and 1.75 mg subcutaneous bremelanotide in premenopausal women.
View PubMed record -
Long-Term Safety and Efficacy of Bremelanotide for HSDD
Long-term extension of the RECONNECT clinical program.
View PubMed record -
FDA Substance Registration — Bremelanotide Acetate
FDA substance record identifying PT-141 as a synonym.
View FDA substance record