Double-Blind, Randomized Clinical Trial Comparing One Percent Buffered Versus Two Percent Unbuffered Lidocaine Injections in Children.

Purpose: Buffered local anesthetics offer an alternative to conventional, unbuffered anesthetic formulations; however, evidence about their use in children is scant. The purpose of this study was to determine the anesthetic and physiologic differences associated with the use of buffered one percent and unbuffered two percent lidocaine (both with 1:100,000 epinephrine) in children. Methods: In this randomized, double-blinded, crossover study, 25 children ages 10 to 12 years old received two inferior alveolar never blocks, at least one week apart, randomized to alternating sequences of two drug formulations: (1) formula A-three mL buffered one percent lidocaine (i.e., including 0.3 mL of 8.4 percent sodium bicarbonate); or (2) formula B-three mL unbuffered two percent lidocaine. Primary outcomes were mean blood lidocaine levels (15 minutes post-injection), timing of clinical signs onset, response to pain on injection, and duration of anesthesia. Analyses relied upon analysis of variance for crossover study designs and a P<0.05 statistical significance criterion. Results: The buffered formulation resulted in significantly lower mean blood lidocaine levels compared to unbuffered-a 63 percent (P<0.05) weight-adjusted relative decrease. The authors found no important differences in pain upon injection, onset, and duration of anesthesia. Conclusion: The buffered local anesthetic formulation showed equal effectiveness with a double-concentration unbuffered formulation while resulting in lower mean blood lidocaine levels-an important gain for the prevention of anesthetic toxicity.