ALKALINIZATION OF LIDOCAINE — why add sodium bicarbonate? Commercial lidocaine solutions are relatively acidic, particularly when epinephrine is added. This improves drug stability—but can make injection more painful and may slow onset. 🧪 The chemistry Lidocaine is a weak base (pKa ≈ 7.9) and exists as: BH⁺ (ionized) ⇌ B (unionized) Only the unionized form readily crosses the lipid nerve membrane. Adding sodium bicarbonate raises the solution pH: ↑ pH → ↑ unionized lidocaine → faster membrane penetration Once inside the axon, lidocaine re-equilibrates, and the ionized form binds the intracellular voltage-gated Na⁺ channel , producing conduction blockade. Read full: https://www.facebook.com/anesthesiamp4/posts/pfbid033CxsiZGmXJ8h8nZ3jNYtGTozir3TraKH868CjgQp7eNsxAgDP3PdyMdhmg8kTzwPl 💉 Why buffer lidocaine? Alkalinization may provide: ↓ Pain on injection Faster onset of neural blockade Potentially improved block quality in some settings A commonly used clinical mixture is appr...