Background and objective To investigate the ability of lidocaine to inhibit reactive oxygen and/or nitrogen species generation by either human leukocytes or cell-free systems via luminol- and lucigenin-enhanced chemiluminescence.

Methods Venous blood was obtained from healthy volunteers and leukocytes were isolated, from which chemiluminescence was generated. Also, chemiluminescence, induced by H2O2, HOCl, peroxynitrite or ferrous iron, was generated in cell-free systems.

Results Lidocaine produced a concentration-dependent inhibition in chemiluminescence generated by leukocytes (92 ± 1%, 1 mM). In cell-free experiments, lidocaine (1 mM) markedly inhibited chemiluminescence of xanthine-xanthine oxidase (24 ± 3%), while it slightly suppressed hypochlorous acid-induced chemiluminescence (9 ± 2%). Peroxynitrite-induced luminol- and lucigenin-enhanced chemiluminescence were also inhibited by lidocaine at 1 mM (19 ± 3% and 48 ± 8%, respectively). Lidocaine did not affect chemiluminescence generated by FeSO4. However, lidocaine produced a biphasic effect on H2O2-induced chemiluminescence (37 ± 5% inhibition at 0.01 mM and 61 ± 17% activation at 1 mM).

Conclusions Lidocaine can elicit direct scavenging activity at high concentrations that might be important at or near the site of injection in local anaesthetic use.