Effects of prilocaine and articaine on human leucocytes and reactive oxygen species in vitro.

Background: The aim of this study was to investigate the ability of local anaesthetics to inhibit reactive oxygen and nitrogen species generated by either stimulated human leucocytes or cell-free systems using luminol chemiluminescence (CL).

Methods: Free radical generation was stimulated in leucocyte assay by formyl-methionyl-leucyl-phenylalanine (FMLP, 2 microM). In cell-free experiments, hydrogen peroxide (H2O2) 3.5 mM, sodium hypochloride 5 microM, ferrous sulphate (FeSO4) 40 nM, peroxynitrite 50 nM and xanthine 0.1 mmol l(-1) plus xanthine oxidase 0.25 U ml(-1) were used to produce H2O2, hypochlorous acid (HOCl), hydroxyl radical, peroxynitrite and superoxide-induced CL, respectively.

Results: Prilocaine inhibited FMLP-induced CL in leucocytes (94+/-1%, at 1 mM), whereas articaine showed an activation (59+/-7%) at high concentration (1 mM) and inhibition (13+/-6%) at low concentration (0.1 mM). In cell-free experiments, prilocaine (22+/-6%, at 1 mM) and articaine (85+/-1%, at 1 mM) caused concentration-dependent inhibition in xanthine-xanthine oxidase-induced CL. Although articaine had no effect on H2O2-induced CL, prilocaine significantly attenuated the H2O2 signal (97+/-0.3%, at 1 mM). Prilocaine (99+/-0.04%, 1 mM) and articaine (70+/-6%, 1 mM) markedly inhibited HOCl-induced CL, whereas these drugs had no effect on FeSO4-induced CL. Articaine inhibited peroxynitrite CL (63+/-6%, 1 mM), but prilocaine did not produce any depression on this signal.

Conclusion: Prilocaine interacted with superoxide, HOCl and H2O2, whereas articaine reacted with superoxide, HOCl, and peroxynitrite. The direct scavenging properties of these drugs might be involved in the inhibition observed in leucocyte assay and could provide experimental support for investigating the potential benefit of using these local anaesthetics in patients presenting pathologies associated with free radical reactions.