What is PT-141 (bremelanotide)?
PT-141 is the development code for bremelanotide, a synthetic cyclic peptide that binds melanocortin receptors. It was developed from Melanotan II, the tanning-research peptide, and the two are closely related in structure. Unlike Melanotan II, bremelanotide went on to become an FDA-approved drug. Research suppliers label their vials PT-141, PT 141 or bremelanotide, all referring to the same compound, and the pt 141 mixing ratio chart below works for any of those labels.
This page does not describe any use in people. It covers one thing: the PT 141 mixing ratio chart and the math of reconstituting a research vial with bacteriostatic water, then reading an amount on a U-100 syringe.
PT 141 mixing ratio chart: how much BAC water per vial
PT-141 research vials are most often labeled 10 mg of freeze-dried powder, with 5 mg vials also sold. The powder amount is fixed; the water you add sets the concentration. The mixing ratio chart below shows micrograms per unit on a U-100 syringe for common water volumes.
| BAC water | 5 mg vial | 10 mg vial |
|---|---|---|
| 1 mL | 50 mcg/unit 5 mg/mL | 100 mcg/unit 10 mg/mL |
| 2 mL | 25 mcg/unit 2.5 mg/mL | 50 mcg/unit 5 mg/mL |
| 3 mL | 16.67 mcg/unit 1.667 mg/mL | 33.33 mcg/unit 3.333 mg/mL |
| 5 mL | 10 mcg/unit 1 mg/mL | 20 mcg/unit 2 mg/mL |
Each cell shows mcg per unit on a U-100 syringe (100 units = 1 mL) and the resulting concentration.
Read across a row to compare the two vial sizes at the same water volume, and down a column to see how more water lowers the micrograms in each unit. A “mixing ratio” is simply vial milligrams divided by water millilitres, so a pt 141 10mg vial is always more concentrated than a 5 mg vial with the same water. The BAC water to peptide ratio guide explains the ratio for every common vial size.
Worked example: PT 141 5mg and 10 mg reconstitution math
The calculator uses three steps. Vial mg ÷ water mL gives the concentration. The amount you enter ÷ that concentration gives the volume in mL. Volume in mL × 100 gives U-100 units. For example, if the amount you already have is 500 mcg, and the vial is 10 mg with 2 mL of water added:
The math: 10 mg ÷ 2 mL = 5 mg/mL (5,000 mcg/mL), which is 50 mcg per unit. 500 mcg ÷ 5,000 mcg/mL = 0.1 mL = 10 units on a U-100 syringe.
The same steps cover a pt 141 5mg reconstitution. For example, if the amount you already have is 250 mcg and the 5 mg vial holds 2.5 mL of water:
The math: 5 mg ÷ 2.5 mL = 2 mg/mL (2,000 mcg/mL), which is 20 mcg per unit. 250 mcg ÷ 2,000 mcg/mL = 0.125 mL = 12.5 units on a U-100 syringe.
Both amounts are arbitrary, chosen because they come out clean; neither is a suggestion. If a result looks 1,000 times off, check whether mg and mcg were swapped, since 1 mg = 1,000 mcg. You can also check the calculator math by hand with the same formula.
PT 141 dosing guide: what this calculator does and does not do
Searches for a pt 141 dosing guide usually want to turn an amount into syringe units. That conversion is what this page provides. You bring the amount; the calculator converts it into mL and units based on your vial size and the water you actually added. It does not set, suggest or check a dose, a schedule or a frequency. Those come from product labeling and a qualified professional.
The chart is a units chart, not a dosing chart. Units are the same size on every U-100 syringe: 100 units = 1 mL and 1 unit = 0.01 mL. A 0.3 mL or 0.5 mL syringe holds fewer units, but each unit is the same volume, so the count from the calculator reads the same on each. The U-100 syringe units to mL guide has the full table.
Bremelanotide reconstitution notes from suppliers
Bremelanotide reconstitution for research vials follows the general pattern for freeze-dried peptides, but the product label decides the details.
- Some suppliers specify bacteriostatic water as the diluent for their vials; check your product’s label before assuming.
- Some labels describe adding the water slowly down the inside wall of the vial and swirling gently rather than shaking, to avoid foaming.
- Storage before and after mixing, and how long a mixed vial is kept, vary by product and come from its labeling.
Because PT-141 and Melanotan II are related, their vials are sometimes confused. Always confirm the name on the label; the Melanotan II reconstitution calculator covers that compound separately.
PT-141 regulatory status
Bremelanotide is FDA-approved as Vyleesi, approved in 2019 and supplied as a prefilled autoinjector with its own labeled strength. That product is ready to use and is not reconstituted. Research vials of PT-141 sold online are not Vyleesi: they are separate, research-labeled products, and a calculator cannot confirm their identity, purity or sterility. For other compounds, browse the peptide library.
PT-141 (Bremelanotide) FAQ
How much BAC water goes in a PT-141 10 mg vial?
There is no single correct volume. More water gives fewer micrograms per unit and less water gives more. The mixing ratio chart shows mcg per unit for several volumes; the product labeling controls what is used.
Is PT-141 the same as bremelanotide?
Yes. PT-141 is the development code for bremelanotide. Research vials may be labeled either way.
Is this a PT 141 dosing guide?
No. It converts an amount you already have into mL and U-100 syringe units. It does not recommend or check a dose, schedule or frequency.
Does the calculator work for a 5 mg PT-141 vial?
Yes. Enter 5 as the vial size and the water you added. The same formula applies to any vial size.
Is bremelanotide FDA-approved?
Yes. Bremelanotide is FDA-approved as Vyleesi, a prefilled autoinjector. Research-labeled PT-141 vials are not that product.