Peplo · Reconstitution calculator
PT-141
Cyclic heptapeptide melanocortin agonist; investigational research name for bremelanotide. FDA-approved as Vyleesi for HSDD.
sexual-healthReconstitution calculator
The total peptide in the vial — the mg number on the label (e.g. 5 mg). This is your whole supply, not one dose.
The sterile water you add to dissolve the powder (this is called reconstituting). More water makes small doses easier to measure.
How much you take in one injection. 1 mg = 1000 mcg.
Draw to 15 units
0.15 mL on a U-100 insulin syringe
A starting reference, not medical advice — see how we source this.
- Half-life
- ~2 h
- Route
- SubQ
- Storage
- Refrigerated 2-8°C; use within ~30 days (~30 days)
- Citations
- 4 referenced
US regulatory status
Bremelanotide is FDA-approved as Vyleesi for hypoactive sexual desire disorder (HSDD).
What is PT-141?
PT-141 is a cyclic heptapeptide melanocortin receptor agonist and the investigational research name for bremelanotide. It has been studied in the context of sexual desire and arousal.
How PT-141 works
Non-selective melanocortin receptor agonist (MC1R/MC3R/MC4R); activates central pathways involved in sexual desire and arousal.
What the research says
The cited literature includes two randomized Phase 3 trials of bremelanotide for HSDD, a review of its role as a melanocortin agonist for sexual dysfunction, and a study of subjective sexual response in premenopausal women. Additional work examines melanocortin-receptor effects on sexual behavior in animal models. Collectively these citations describe investigations of central melanocortin pathways involved in sexual desire and arousal.
- 2004PT-141: a melanocortin agonist for the treatment of sexual dysfunction
- 2005Selective facilitation of sexual solicitation in the female rat by a melanocortin receptor agonist
- 2006An effect on the subjective sexual response in premenopausal women with sexual arousal disorder by bremelanotide (PT-141), a melanocortin receptor agonist
- 2019Bremelanotide for the Treatment of Hypoactive Sexual Desire Disorder: Two Randomized Phase 3 Trials
Evidence limitations
The research characterizes what was examined without asserting a universal outcome.
Safety & use boundary
As a prescription medication (bremelanotide/Vyleesi), PT-141 should be used only under the supervision of a qualified clinician. This information is for general education and is not medical advice.
Published protocols
Dosing figures reported in the cited research. Educational reference, not a recommendation.
- 2019 study
recovery
500–1500 mcg, once daily
How to reconstitute PT-141
New to this? Here's the whole process, start to finish. Educational only — not medical advice.
What you'll need
- The PT-141 vial — a small glass vial of white, freeze-dried powder
- Bacteriostatic water — the liquid you mix in (not plain sterile or tap water)
- U-100 insulin syringes — the small syringes marked in units
- Alcohol swabs to wipe the vial tops before you touch them with a needle
- A spot in the fridge to keep it once it's mixed
Step by step
Wipe everything down
Swab the rubber top of both the peptide vial and the bacteriostatic water with an alcohol wipe. Clean tops are what keep the mixed solution good for weeks instead of days.
Draw the water
Use the calculator above to see how much bacteriostatic water to add for your vial size. Pull exactly that amount out of the water vial with a syringe.
Add it slowly
Push the needle into the peptide vial and let the water run gently down the inside glass wall — don't blast it straight onto the powder.
Let it dissolve
Swirl the vial gently or just let it sit. The powder goes into solution on its own in a minute or two. Never shake it hard.
Read your draw
Enter your vial size, the water you added, and your dose in the calculator. It shows the exact units to pull into your syringe — you never do the math yourself.
Store it cold
Cap it and keep it in the fridge. PT-141 stays good for about 30 days once it's mixed.
Reading your dose
The calculator gives you a number like “Draw to 20 units.” Units are just the numbered marks on a U-100 insulin syringe (100 units fill 1 mL). “20 units” means pull the plunger back to the 20 mark. You don't convert milligrams to micrograms in your head — that's the whole point of the calculator. If you're brand new to injecting, learn proper technique and site rotation from a qualified clinician or nurse before your first dose; this page covers the mixing and measuring, not the injection itself.
Storing it
Before mixing: Refrigerated Once reconstituted: Refrigerated 2-8°C; use within ~30 days (about 30 days). Don't freeze a reconstituted vial.
What “cycling” means
Many peptides are used in “cycles” — a stretch of daily or weekly use (“on”), then a break (“off”), rather than continuously. Cycling gives the body a rest and is a common pattern in the research. Any specific on/off lengths for a compound live in its published protocols above, drawn from the cited studies — this site shows you what the research used, it doesn't recommend a schedule for you.
Which form do you have?
PT-141 is sold in more than one form — each is used differently.
- Injectable vial
- Ships as a freeze-dried powder you reconstitute with bacteriostatic water and draw on a U-100 insulin syringe — the reconstitution steps above walk through it.
- Nasal spray
- The powder is reconstituted and loaded into a nasal spray bottle rather than drawn into a syringe; each pump delivers a metered amount. Prime a new bottle with a few sprays before the first dose.
Common first-timer mistakes
Shaking the vial to mix it
Swirl it gently or just let it sit. Shaking can damage delicate peptides — you want the powder to dissolve, not foam.
Using tap water or plain sterile water
Use bacteriostatic water. Plain sterile water has no preservative, so a mixed vial spoils in a day or two instead of lasting weeks.
Leaving a mixed vial on the counter
Keep reconstituted vials in the fridge. Heat and light break the peptide down faster.
Eyeballing the dose instead of measuring
Use the calculator and draw to the exact unit mark on the syringe. Guessing a tiny volume is where most measuring errors happen.
Reusing needles
Use a fresh syringe each time. A used needle is duller, hurts more, and is no longer sterile.
Mixing up mg and mcg
1 mg = 1000 mcg. The calculator keeps them straight so you don't have to — just enter your dose in the unit it asks for.
Words you'll see
- Reconstitution
- Mixing a freeze-dried peptide powder with liquid (bacteriostatic water) so it can be drawn into a syringe.
- Bacteriostatic water
- Sterile water with a tiny amount of benzyl alcohol that stops bacteria growing, so a mixed vial keeps for weeks. Not the same as plain sterile water.
- U-100 insulin syringe
- A small syringe marked in “units,” where 100 units = 1 mL. Peptide draws are measured in these units.
- Subcutaneous (SubQ)
- An injection into the fatty layer just under the skin, rather than into muscle or a vein.
- mcg vs mg
- 1 mg = 1000 mcg. Doses are often written in micrograms (mcg); the calculator handles the conversion for you.
- Lyophilized
- Freeze-dried. The powder in the vial is the peptide with its water removed so it stays stable on the shelf.
- Half-life
- Roughly how long it takes your body to clear half of a dose — a rough sense of how long it stays active.
Common questions
What is PT-141?
Cyclic heptapeptide melanocortin agonist; investigational research name for bremelanotide. FDA-approved as Vyleesi for HSDD. Non-selective melanocortin receptor agonist (MC1R/MC3R/MC4R); activates central pathways involved in sexual desire and arousal.
How is PT-141 reconstituted?
PT-141 ships as a lyophilised powder and is reconstituted with bacteriostatic water before use, then drawn on an insulin syringe. Use the calculator above to see the exact units to draw for your vial size and dose. This is a reference tool, not medical advice.
What is the half-life of PT-141?
Research reports an approximate half-life of 2 hours for PT-141. Half-life informs how frequently a compound is studied; it is not a dosing instruction.
How should PT-141 be stored?
Refrigerated Once reconstituted: Refrigerated 2-8°C; use within ~30 days (about 30 days). This is general storage information, not medical advice.
What is PT-141 commonly studied alongside?
In the research literature PT-141 is often discussed together with melanotan ii. Co-occurrence in studies is not an endorsement of any combination.
Related compounds
Keep your protocol, doses, and vials in one place.
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