Retatrutide 40 mg vial
How much bacteriostatic water to add to a 40 mg vial of Retatrutide, the syringe units for each common dose, and how many doses the vial holds.
- Water
- 2 mL
- Strength
- 20 mg/mL
- Common dose
- 2 mg
- Draw
- 10 units0.10 mL
- Doses per vial
- 20
The short answer
Mixed with 2 mL of bacteriostatic water, a 40 mg vial of Retatrutide holds 20 mg/mL. A 2 mg dose is then 10 units (0.10 mL) on a U-100 insulin syringe, and the vial holds about 20 doses of that size. Taken 1× per week, it lasts about 20 weeks.
How much water
The water only sets the strength; the dose and the number of doses in the vial stay the same. Draws are on a U-100 insulin syringe, where 1 unit is 0.01 mL.
| Water added | Strength | Per syringe unit | Draw for 2 mg |
|---|---|---|---|
| 1 mL | 40 mg/mL | 400 mcg | 5 units (0.05 mL) |
| 2 mL | 20 mg/mL | 200 mcg | 10 units (0.10 mL) |
| 3 mL | 13.33 mg/mL | 133 mcg | 15 units (0.15 mL) |
Dose chart
Syringe units for each common dose at each water volume. Select a cell to open it in the calculator.
| Dose | Water added | ||
|---|---|---|---|
| 1 mL | 2 mL | 3 mL | |
| 2 mg | |||
| 4 mg | |||
| 6 mg | |||
| 9 mg | |||
| 12 mg | |||
Draws over 100 units show in mL. Faded values are under 2 units, which is hard to measure. Check that your vial holds the larger volumes.
Where the doses come from
- Trial Phase 3 maintenance doses of 4, 9 or 12 mg once weekly, reached by starting at 2 mg and stepping up every 4 weeks. At 80 weeks the 12 mg group lost 28.3% of body weight among people who stayed on treatment (25.0% counting everyone who started).
- Trial Phase 2 tested 1, 4, 8 and 12 mg weekly for 48 weeks. Mean weight loss was 24.2% at 12 mg.
Doses are what labels, trials or community reports reference, not recommendations. Retatrutide’s page has the cycle, side effects, cautions and sources.
Mixing and storage
- PrepareLet a refrigerated vial come to room temperature, and wipe both stoppers with an alcohol swab.
- Add 2 mLDraw 2 mL of bacteriostatic water and let it run slowly down the inside wall of the vial.
- Swirl, don’t shakeSwirl gently until the powder dissolves and the liquid is clear.
- Label itWrite the date and the strength, 20 mg/mL, on the vial.
Storage: No label exists. Usual practice: powder frozen or refrigerated; mixed vials at 2–8 °C, protected from light.
The reconstitution guide covers each step, and the units page explains syringe markings.
Questions
How much water do I add to a 40 mg vial of retatrutide?
There’s no single right amount: the water only sets the strength. With 2 mL of bacteriostatic water, a 40 mg vial holds 20 mg/mL. With 1 mL it’s 40 mg/mL; with 3 mL it’s 13.33 mg/mL. Less liquid makes each dose a smaller draw; more makes small doses easier to measure.
How many units is 2 mg of retatrutide?
With 2 mL in a 40 mg vial, 2 mg is 10 units (0.10 mL) on a U-100 insulin syringe. With 1 mL, 5 units (0.05 mL); with 3 mL, 15 units (0.15 mL).
How many doses are in a 40 mg vial of retatrutide?
About 20 doses of 2 mg, or 4 of 9 mg or 3 of 12 mg. Taken 1× per week at 2 mg, it lasts about 20 weeks.
How long does a mixed vial of retatrutide keep?
No label exists. Usual practice: powder frozen or refrigerated; mixed vials at 2–8 °C, protected from light.
Other vial sizes
Sources
- Jastreboff et al., Phase 2 trial (NEJM 2023) doi:10.1056/NEJMoa2301972
- Jastreboff et al., retatrutide for obesity, TRIUMPH-1 (NEJM 2026) PMID 42814954
The math on this page uses the doses and storage on Retatrutide’s page.