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How to reconstitute retatrutide
Compounded retatrutide ships as a freeze-dried powder, so before you can dose it you have to add liquid and work out the units. This is the plain version: what you need, the mixing steps, a dose-to-units chart for common vial sizes, and how to store it. Retatrutide is investigational and not FDA-approved; this explains the mechanics, it is not a prescription or a recommendation to use it.
Concentration = vial mg ÷ water mL. Units to draw = (dose mg ÷ concentration) × 100 on a U-100 syringe. Everything below is just applying those two lines. Or skip the arithmetic and use the reconstitution calculator.
What you need
- • A lyophilized retatrutide vial (commonly 5, 10, 12, or 30 mg)
- • Bacteriostatic water (sterile water with 0.9% benzyl alcohol - the preservative is what makes a multi-dose vial safe to draw from repeatedly)
- • A U-100 insulin syringe for dosing (and a larger syringe for adding water, optional)
- • Alcohol swabs, clean hands, a clean surface
The steps
Prep. Wash your hands. Swab the rubber tops of both the retatrutide vial and the bacteriostatic water with alcohol and let them dry.
Choose your water volume. This sets the concentration. A simple default is 1 mL of bacteriostatic water per vial. More water = more dilute (bigger, easier-to-read volumes at low doses); less = more concentrated.
Add the water slowly. Insert the needle and let the water run down the inside glass wall, not blasting directly onto the powder. This avoids foaming, which can damage the peptide.
Dissolve gently. Swirl the vial or roll it between your palms. Do not shake. Wait until the solution is completely clear (usually a minute or two). A cloudy or particulate solution should not be used.
Draw your dose in units. Compute units from your concentration (chart below), swab the top again, and draw the dose on a U-100 syringe, tapping out air bubbles.
Label and store. Write the concentration and the date on the vial, and refrigerate it. Discard by your beyond-use date.
Dose-to-units chart
Assuming 1 mL of bacteriostatic water per vial, here is what each dose comes out to on a U-100 syringe. If you use a different water volume, recompute, do not copy these blindly:
| Vial (+ 1 mL water) | Concentration | 2 mg dose | 4 mg dose | 6 mg dose |
|---|---|---|---|---|
| 5 mg | 5 mg/mL | 40 units | 80 units | 120 units* |
| 10 mg | 10 mg/mL | 20 units | 40 units | 60 units |
| 12 mg | 12 mg/mL | ~17 units | ~33 units | 50 units |
| 30 mg | 30 mg/mL | ~7 units | ~13 units | 20 units |
*A dose needing more than 100 units exceeds a single U-100 syringe at that concentration, add more water (more dilute) or split the draw. This is exactly the kind of edge case the calculator flags for you.
Storage & beyond-use dating
Reconstituted peptide is more fragile than the dry powder. A common default is about 28 days refrigerated, but keep it conservative: minimize time at room temperature, never freeze-thaw repeatedly, keep it out of light, and discard by the date on your label. The dry, unreconstituted vial is far more stable, only mix what you will use within the vial's in-use window. For the underlying stability and diluent basics, see the sources below.
Common mistakes
- • Shaking instead of swirling - foaming shears the peptide.
- • Copying someone else's "units" without matching their vial size and water volume - the units only mean anything relative to your concentration.
- • Blasting water onto the pellet instead of down the wall.
- • Using non-preserved or non-sterile water for a multi-dose vial.
- • Not labeling the vial - a month later you won't remember the concentration or the date.
This page explains reconstitution mechanics; it is not medical advice or an endorsement of using retatrutide, which is investigational and not FDA-approved. Compounded and research-use-only vials are not quality-controlled, stated strength, purity, and sterility can be wrong, which no amount of careful mixing fixes. See the US peptide/compounding status. Any decision to use it belongs with a licensed clinician.
Skip the arithmetic
OptiPin's free reconstitution calculator takes your vial size, water volume, and target dose and returns the exact units - and the app then logs every draw, tracks the vial's remaining supply, and warns you before it runs out or expires. iOS, on-device.
Open the calculatorFrequently asked questions
How much bacteriostatic water do you add?
There's no required amount - the water volume sets the concentration and you pick it for convenient dosing. 1 mL per vial is common (a 10 mg vial becomes 10 mg/mL). More water = more dilute; less = more concentrated. Always compute units from the concentration you actually made.
How many units is a retatrutide dose?
It depends on concentration. On U-100, 100 units = 1 mL. A 10 mg vial + 1 mL water (10 mg/mL) makes a 2 mg dose = 20 units, 6 mg = 60 units. Different vial or water volume changes the units - recompute from your own vial.
What water do you use?
Bacteriostatic water (sterile water with 0.9% benzyl alcohol) for multi-dose vials, the preservative allows repeated withdrawals. Plain sterile water is single-use. Never use tap or non-sterile water.
How long does reconstituted retatrutide last?
A common default is ~28 days refrigerated, but it depends on diluent, storage, and product. Keep it cold, minimize room-temp time, avoid freeze-thaw, and discard by your labeled date. When unsure, be conservative.
Sources & further reading
- Bacteriostatic Water for Injection, USP - DailyMed label (0.9% benzyl alcohol; multi-dose reconstitution diluent).
- USP General Chapter <797> - Pharmaceutical Compounding, Sterile Preparations (aseptic technique, beyond-use dating).
- Retatrutide dosing & titration (which dose to draw once it's mixed).
U-100 syringe: 100 units = 1 mL. Vial strengths and fill volumes vary; always verify your vial's stated strength. Retatrutide is investigational; this is not medical advice.
Related
Reconstitution calculator · Retatrutide dosing · Retatrutide tracker · Injection technique · Peptide guide