Fig. 4. Time course of analgesia after injection of commercial 0.5% lidocaine solutions with epinephrine: lidocaine with epinephrine (1:100,000; □ CLE; pH = 6.5; n = 10); lidocaine with epinephrine (1:100,000) and 8.4% sodium bicarbonate (10:1; ▪ CLBCE; pH = 7.9; n = 10); control (⋄ n = 4).