Posted by Greg_T (Verified Patient)•2026-11-05
I was reconstituting a 10 mg lyophilized powder vial and accidentally pushed 2.0 mL of bacteriostatic water into the vial instead of the 1.0 mL my doctor recommended. Did I ruin the medication? How many units do I take now for my 2.5 mg dose?
✓ ACCEPTED CLINICAL ANSWERDr. Elena Rivera, M.D.
Greg, the good news is you did not ruin the peptide. Tirzepatide dissolves readily in 2.0 mL of bacteriostatic water, and the preservative ratio (0.9% benzyl alcohol) remains completely active and sterile.
All you have done is diluted the concentration by half:
- 10 mg dissolved in 1.0 mL = 10 mg/mL concentration.
- 10 mg dissolved in 2.0 mL = 5 mg/mL concentration.
Your New Dose Calculation for 2.5 mg:
- Prescribed Dose: 2.5 mg
- New Concentration: 5 mg/mL
- 2.5 mg ÷ 5 mg/mL = 0.50 mL
- On a U-100 syringe: 0.50 mL = 50 units.
Instead of drawing 25 units, you will draw 50 units. You will still receive the exact same 2.5 milligrams of active drug. Use our [Bacteriostatic Water Dilution Calculator](/tools/tirzepatide-bac-water-calculator/) to double-check any diluent ratios before injecting.