The short answer: how much BAC water for a 10 mg retatrutide vial?
For a 10 mg retatrutide vial, the most practical starting point is 2 mL of bacteriostatic water, which gives you a concentration of 5 mg/mL.
At a 2 mg starting dose (a common retatrutide initiation dose), that equals 40 units on a 100-unit (1 mL) insulin syringe.
Use our BAC water calculator to model different water volumes and doses, or the dedicated retatrutide dosage calculator to get exact syringe units for your vial — the table below covers the most common setups.
Retatrutide reconstitution reference table
| BAC water added | Concentration | 2 mg dose | 4 mg dose | 6 mg dose |
|---|---|---|---|---|
| 1 mL | 10 mg/mL | 20 units | 40 units | 60 units |
| 2 mL | 5 mg/mL | 40 units | 80 units | 120 units |
| 3 mL | 3.33 mg/mL | 60 units | 120 units | 180 units |
All units are on a standard 100-unit (1 mL) insulin syringe.
Why bacteriostatic water?
Bacteriostatic water (BAC water) contains 0.9% benzyl alcohol, which acts as a preservative. This extends the shelf life of your reconstituted peptide solution to approximately 28–30 days when refrigerated at 2–8°C.
Sterile water can technically reconstitute peptides, but it lacks the preservative — making it suitable only for single-use preparations. For multi-dose vials like retatrutide (which is typically dosed weekly or multiple times per week), BAC water is the correct choice.
Step-by-step: how to add BAC water to a 10 mg retatrutide vial
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Gather your supplies. You'll need your 10 mg retatrutide vial, a vial of bacteriostatic water, a sterile insulin syringe, and alcohol swabs.
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Swab both vials. Wipe the rubber stoppers of both vials with 70% isopropyl alcohol and allow to air-dry for 10–15 seconds.
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Draw the BAC water. Using a sterile syringe, draw your chosen volume (typically 2 mL) of bacteriostatic water.
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Inject slowly against the glass wall. Insert the needle into the retatrutide vial. Inject the water slowly, aiming the stream at the inside glass wall at a 45° angle — never directly onto the lyophilized powder.
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Gently swirl until dissolved. Gently rotate the vial to dissolve the powder. Do not shake. The solution should become completely clear within a minute or two. If it's slightly cloudy, give it a few more minutes at room temperature.
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Store properly. Refrigerate at 2–8°C. Do not freeze. Reconstituted retatrutide with BAC water is typically stable for 28–30 days refrigerated when kept away from light.
What concentration should I use for retatrutide?
There's no single "right" concentration — it depends on your prescribed dose and how many units you prefer to draw. Common preferences:
- Higher concentration (1–2 mL water): Fewer units per dose, smaller injection volume. Better for higher doses (e.g., 8 mg+). Harder to measure very small starter doses accurately.
- Lower concentration (2–3 mL water): More units per dose, larger injection volume. Better for precise measurement of lower starter doses (e.g., 2 mg = 40 units at 5 mg/mL is easy to read on most syringes).
Most people find 2 mL (5 mg/mL) to be a practical middle ground. This gives a manageable injection volume across the typical retatrutide dose range of 2–8 mg/week.
