How much bacteriostatic water do I add to a PT-141 vial?

Use the volume in your product's instructions or from your prescriber or pharmacist. The water doesn't change how much PT-141 is in the vial, only the concentration: a 10 mg vial with 2 mL is 5 mg/mL, and adding more water makes each unit on the syringe hold less.

How do I convert PT-141 from mg to syringe units?

Divide the amount in mg by the concentration in mg/mL to get mL, then multiply by 100 for a U-100 insulin syringe (50 for U-50, 40 for U-40). The calculator on this page does it when you enter the amount from your prescriber or label.

Does this calculator give a PT-141 dose?

No. The calculator's amount field starts empty and Caliper never suggests an amount. For reference, this page quotes the dosing section of the FDA label for Vyleesi, which applies only to that branded product. Your dose comes from your prescriber.

How should I store PT-141 after mixing?

Follow the storage section of your product's label or the pharmacy's instructions. The notes on this page summarize what the FDA label says for the branded product. For any mixed vial, write the mixing date on it and respect the use-by date.

PT-141 reconstitution calculator

Concentration and syringe-unit math for PT-141 vials (10 mg), with the calculator set up for a 10 mg vial and 2 mL of diluent. Change both to match your own vial.

FDA-approved product existsOther

PT-141 is the research name for bremelanotide, a melanocortin receptor agonist. Bremelanotide is FDA-approved as VYLEESI for premenopausal women with acquired, generalized hypoactive sexual desire disorder (HSDD).

FDA-approved product: Vyleesi. The official label dosing for the branded product is quoted further down this page for reference. It applies only to that product, and it is never filled into the calculator. Products sold for “research use only” are not the approved drug.

Reconstitution calculator

Enter the numbers from your own vial, and pick the syringe in your hand. Check the U- number and size printed on the syringe box.

Concentration

5 mg/mL

5,000 mcg/mL

Draw volume

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Syringe units

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U-100 1 mL, holds 100

Draws in the vial

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1Concentration: 10 mg ÷ 2 mL = 5 mg/mL
2Draw volume: amount in mg ÷ 5 mg/mL = draw mL
3Syringe units: draw mL × 100 units per mL (U-100) = units

Math only, not dosing advice. Follow your prescriber or label. Real vials give slightly less than the full-draw count: a little liquid stays in the vial and needle. Your last setup is saved in this browser only; Clear removes it.

Save your vial in Caliper and it remembers the concentration and use-by date you entered, alongside your dose log. The calculator above is a browser tool and is not part of the app.

Save my vial in Caliper

The calculator starts with a 10 mg vial and 2 mL of diluent as an example setup, not a recommendation. Enter the vial size on your label and the volume you actually added. The amount field starts empty: Caliper never suggests an amount.

PT-141 concentration by vial size

Vial mg ÷ mL of diluent = mg per mL. Plain arithmetic for PT-141 label sizes; the volumes are examples, not recommendations.

PT-141: mg/mL by vial size and diluent volume
Vial	1 mL	2 mL	3 mL
10 mg	10 mg/mL	5 mg/mL	3.333 mg/mL

Syringe units to mg at 5 mg/mL

What a given number of U-100 units holds when a 10 mg vial has 2 mL added. This is a unit conversion, like a map scale, not a dose. A different vial size or volume changes every row, so use the calculator for your own numbers.

10 mg vial + 2 mL (5 mg/mL): conversion only
U-100 units	mL	mg	mcg
5 units	0.05	0.25	250
10 units	0.1	0.5	500
20 units	0.2	1	1,000
25 units	0.25	1.25	1,250
50 units	0.5	2.5	2,500

Mixing and storing PT-141

For a powder vial, a 10 mg vial with 2 mL is 5 mg/mL; with 1 mL it's 10 mg/mL.

VYLEESI's label says to store it at or below 25°C (77°F), not to freeze it, and to protect it from light.

Research vials don't come with FDA-reviewed storage or stability data. Follow the storage line on the vial label, keep the vial away from heat and light, and write the date on it when you mix it. Our storage guide covers fridge temperatures, use-by dates and travel.

Status: FDA-approved as VYLEESI, a prefilled autoinjector (1.75 mg/0.3 mL), so the approved product needs no reconstitution. Powder vials sold as PT-141 for "research use only" are not the approved product and are not reviewed by the FDA.

More detail: how to reconstitute peptides and how to store peptides and GLP-1s. To convert units you've already drawn, use the units-to-mg converter.

Official FDA label dosing for Vyleesi

Follow your prescriber's instructions. This is not medical advice. The text below is quoted exactly from the current FDA prescribing information (section cross-references removed). It is the official label schedule for the branded product named and does not apply to compounded or research products. Labels change; the linked label is the authority.

VYLEESI (bremelanotide injection) autoinjector: label schedule

Indication (from the label): “VYLEESI is indicated for the treatment of premenopausal women with acquired, generalized hypoactive sexual desire disorder (HSDD) … VYLEESI is not indicated for the treatment of HSDD in postmenopausal women or in men.”

“Inject 1.75 mg subcutaneously via the autoinjector to the abdomen or thigh, as needed, at least 45 minutes before anticipated sexual activity.”
“Do not administer more than one dose within 24 hours.”
“More than 8 doses per month is not recommended.”

Source: VYLEESI (bremelanotide) prescribing information, DailyMed, label version effective November 13, 2025; checked October 17, 2026.

FAQ

How much bacteriostatic water do I add to a PT-141 vial?: Use the volume in your product's instructions or from your prescriber or pharmacist. The water doesn't change how much PT-141 is in the vial, only the concentration: a 10 mg vial with 2 mL is 5 mg/mL, and adding more water makes each unit on the syringe hold less.
How do I convert PT-141 from mg to syringe units?: Divide the amount in mg by the concentration in mg/mL to get mL, then multiply by 100 for a U-100 insulin syringe (50 for U-50, 40 for U-40). The calculator on this page does it when you enter the amount from your prescriber or label.
Does this calculator give a PT-141 dose?: No. The calculator's amount field starts empty and Caliper never suggests an amount. For reference, this page quotes the dosing section of the FDA label for Vyleesi, which applies only to that branded product. Your dose comes from your prescriber.
Is PT-141 FDA-approved?: FDA-approved as VYLEESI, a prefilled autoinjector (1.75 mg/0.3 mL), so the approved product needs no reconstitution. Powder vials sold as PT-141 for "research use only" are not the approved product and are not reviewed by the FDA.
How should I store PT-141 after mixing?: Follow the storage section of your product's label or the pharmacy's instructions. The notes on this page summarize what the FDA label says for the branded product. For any mixed vial, write the mixing date on it and respect the use-by date.

Related compounds

Calculators by vial size

The same arithmetic for any compound, with a 1, 2 and 3 mL concentration table.

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Sources

Updated October 17, 2026

For adults 18+. Educational math only, not medical advice. This page does not recommend any dose, dilution, syringe or compound, and doesn't say where to get one. Always follow your prescriber's instructions and the product label, and ask a pharmacist if a number doesn't look right.