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 — 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.
How to calculate your syringe units for any dose
Once you know your concentration:
Formula: Units = (Dose in mg ÷ Concentration in mg/mL) × 100
Examples at 5 mg/mL (2 mL BAC water into 10 mg vial):
- 2 mg dose: (2 ÷ 5) × 100 = 40 units
- 4 mg dose: (4 ÷ 5) × 100 = 80 units
- 6 mg dose: (6 ÷ 5) × 100 = 120 units (needs a 2 mL syringe for this volume)
For anything beyond 8 mg, you may need to split into two injections or use a lower concentration (3 mL water = 3.33 mg/mL).
Use our peptide reconstitution calculator to instantly convert any dose to syringe units for your specific setup.
Frequently asked questions
Can I store reconstituted retatrutide at room temperature?
No. Reconstituted peptides should be refrigerated at 2–8°C immediately after preparation. Room temperature storage significantly reduces stability. Unreconstituted lyophilized powder can tolerate room temperature for short periods, but once reconstituted, always refrigerate.
What happens if I use too much or too little BAC water?
Using more BAC water than intended lowers your concentration and increases the units per dose. Using less raises concentration and decreases units per dose. Neither is inherently dangerous if you recalculate your dose accordingly — just make sure you update your syringe units calculation based on the actual volume you used.
Can I mix retatrutide with other peptides in the same vial?
No. Each peptide should be reconstituted in its own vial. Mixing peptides in the same vial is not recommended unless specifically formulated that way by a compounding pharmacy. You can draw two separate peptides into one syringe for injection, but each should be reconstituted separately.
Is retatrutide available by prescription?
Retatrutide is currently in clinical trials and is not yet FDA-approved. It may be available through specific clinical trial programs or compounding pharmacies under certain circumstances. Consult with a licensed clinician to discuss your options.
Find a clinic that offers GLP-1/GIP/GCG peptide therapy
Retatrutide is a triple-receptor agonist (GLP-1/GIP/GCG). If you're looking for a provider who can guide you through dosing, titration, and monitoring, our peptide clinic directory lists verified providers across the United States.
Medical disclaimer: This article is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider before starting any peptide therapy.
