Retatrutide reconstitution calculator
Calculate retatrutide reconstitution for Phase 3 protocol doses 1mg through 12mg. Includes concentration, injection volume, syringe units, and storage guidance.
Retatrutide reconstitution requires the same equipment and principles as other research peptides — bacteriostatic water and U-100 insulin syringes — but the Phase 3 protocol dose structure introduces specific reconstitution considerations that differ from flat-dose peptides like BPC-157.
The TRIUMPH-1 trial escalation schedule covers a 12-fold dose range: 1mg → 2mg → 4mg → 8mg → 12mg. Each step requires a minimum of 4 weeks before escalation. This means researchers will reconstitute the same vial multiple times at potentially different concentration targets, or reconstitute separate vials for each dose level.
The most practical approach for a 12-dose-level protocol is to use a consistent water volume (typically 2mL) regardless of the dose being prepared. This gives a clean standard concentration for each vial size. For a 12mg vial with 2mL water: 6000 mcg/mL concentration. For a 4mg vial with 2mL water: 2000 mcg/mL. The injection volumes at these concentrations remain small (0.1-0.5mL) and manageable with standard 1mL insulin syringes.
The small injection volumes at lower protocol doses (1mg, 2mg) require particular precision. A 1mg dose from a 6000 mcg/mL solution requires drawing only 16.7 microliters — approximately 1.7 units on a U-100 syringe. At this volume, small measurement errors represent a large percentage of the dose. Consider using a more dilute concentration (1mL water per vial instead of 2mL) for lower dose levels to achieve larger, more measurable injection volumes.
Store reconstituted retatrutide at 2-8°C. Do not freeze. Stable for approximately 28 days. Protect from light.
Phase 3 protocol note
Retatrutide Phase 3 trial used pre-filled auto-injector pens. Research vials require manual reconstitution. Starting dose is 1 mg/week, escalating every 4 weeks to a maximum of 12 mg/week.
calc.dose
1 mg
1,000 mcg
calc.concentration
2.50 mg/mL
2500 mcg/mL
calc.injectionVolume
0.400 mL
40 units (U-100)
calc.dosesPerVial
5
5mg vial at 1mg/dose
calc.storageGuidance
Store lyophilized retatrutide at −20°C. After reconstitution with bacteriostatic water, refrigerate at 2–8°C. Use within 28 days. Avoid freeze-thaw cycles. Inject subcutaneously into abdomen, thigh, or upper arm — rotate sites weekly.
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Frequently asked questions
How do I reconstitute retatrutide for the starting 1mg dose?+
For a 1mg vial: add 1mL of bacteriostatic water for a concentration of 1000 mcg/mL. This gives an injection volume of 1mL for a 1mg dose — the full syringe. Alternatively, add 2mL water for 500 mcg/mL, requiring 2mL for a 1mg dose. The 1mL reconstitution is more practical at this dose level. Draw slowly to minimize bubble formation.
How much bacteriostatic water should I add to a retatrutide vial?+
For most dose levels, 2mL of bacteriostatic water per vial is the standard approach. This gives manageable injection volumes while maintaining sufficient concentration for accurate dosing. Exception: for the 1mg starting dose, consider 1mL water to get a 1mL injection volume rather than a precision-demanding 0.5mL. The calculator shows the injection volume for your selected water volume and dose.
How long is reconstituted retatrutide stable in the refrigerator?+
Reconstituted retatrutide is stable for approximately 28 days at 2-8°C in bacteriostatic water. As a larger, more complex molecule than peptides like BPC-157 or sermorelin, retatrutide maintains potency well under refrigerated conditions. Do not store at room temperature. Do not freeze. Keep away from light — store in the original vial or a dark-colored container if possible.
What syringe should I use for retatrutide injections?+
U-100 insulin syringes (1mL barrel, 100 units total) are standard. For doses requiring injection volumes of 0.5-1mL, a 1mL syringe works well. For precision at lower doses (1-2mg) with more concentrated solutions resulting in small injection volumes, a 0.5mL (50 unit) syringe provides better graduation accuracy. 28-31 gauge needles minimize injection site discomfort for subcutaneous administration.
Can I freeze reconstituted retatrutide to extend shelf life?+
No. Freezing reconstituted retatrutide causes ice crystal formation that disrupts the molecular structure and reduces biological activity. If you have more reconstituted solution than can be used in 28 days, discard the excess and reconstitute only what is needed. Lyophilized (unreconstituted) retatrutide can be stored frozen in sealed vials for extended periods — the freeze-drying process was specifically designed to allow this.
Research background
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