Purpose. To investigate whether increasing the pH of lidocaine could reduce the pain caused by its skin infiltration as well as that caused by intravenous and epidural needle insertion.

Methods. A randomized, double-blind trial was undertaken in patients who were allocated to receive topical anesthesia with either plain (plain group; n = 25) or alkalinized lidocaine (alkalinized group; n = 25). An alkalinized lidocaine solution was prepared by adding 8.4% sodium bicarbonate to a plain 1% lidocaine solution at a ratio of 1 : 10. Pain was assessed using the verbal analog scale (VAS).

Results. In the alkalinized group, the VAS scores on skin infiltration in the hand (2.5 ± 1.4) and the back (2.7 ± 1.4) were significantly lower than the respective scores in the plain group (3.5 ± 1.4, and 4.9 ± 1.9). Although the VAS score on intravenous needle insertion did not differ between the two groups, the VAS score on epidural needle insertion was significantly lower in the alkalinized group (1.3 ± 1.0) than in the plain group (3.6 ± 1.3).

Conclusions. Alkalinization of lidocaine was effective in attenuating pain on skin infiltration and on epidural needle insertion.