Sodium Bicarbonate Ampule Concentrations
Sodium bicarbonate ampules are commercially available in three standard concentrations: 4.2%, 7.5%, and 8.4%, with 8.4% being the most commonly used concentration in clinical practice. 1
Standard Ampule Formulations
The FDA-approved sodium bicarbonate injection formulations contain the following specifications 1:
- 8.4% solution: Contains 84 mg/mL of NaHCO₃, providing 1 mEq/mL each of Na⁺ and HCO₃⁻ (osmolarity: 2 mOsmol/mL)
- 7.5% solution: Contains 75 mg/mL of NaHCO₃, providing 0.9 mEq/mL each of Na⁺ and HCO₃⁻ (osmolarity: 1.79 mOsmol/mL)
- 4.2% solution: Contains 42 mg/mL of NaHCO₃, providing 0.5 mEq/mL each of Na⁺ and HCO₃⁻ (osmolarity: 1 mOsmol/mL)
Available Vial Sizes
Sodium bicarbonate injection is supplied in 1:
- 10 mL vials (available in 8.4% and 4.2% concentrations)
- 50 mL vials (available in 8.4% and 7.5% concentrations)
Age-Specific Concentration Requirements
For newborn infants and children under 2 years of age, only the 0.5 mEq/mL (4.2%) concentration should be used. 2, 3 This requires diluting the standard 8.4% solution 1:1 with normal saline or sterile water before administration. 2
For children ≥2 years and adults, the 8.4% solution may be used without dilution, though dilution is often performed for safety. 2
Clinical Context for Local Anesthesia
When sodium bicarbonate is added to local anesthetics for buffering purposes (to reduce injection pain), the concentration used is typically 8.4% sodium bicarbonate mixed with 1% lidocaine with epinephrine in a 1:9 or 1:10 ratio by volume. 4 This creates a final bicarbonate concentration of approximately 10-100 mEq/L in the anesthetic solution. 4