[Neutralization of lidocaine-adrenaline. A simple method for less painful application of local anesthesia].

The amount of sodium bicarbonate necessary to neutralise commercially available lignocaine-epinephrine (pH 4.7) to physiologically neutral pH (7.4) was established. The analysis showed that neutral pH could be accomplished by adding 1.0 ml sodium bicarbonate (8.4 g/l) to 10 ml lignocaine-epinephrine (1%, 5 microgram/ml). Chemical analysis also established that the neutralised lignocaine-epinephrine was stable for 24 hours after adding sodium bicarbonate. A double-blinded randomised clinical trial with crossover design done on volunteers from hospital staff proved that injection of neutralised lignocaine-epinephrine is less painful than commercially available lignocaine-epinephrine (p < 0.001).