The influence of different volatile inhaled anesthetics on the plasma protein binding of lidocaine

The author investigated the interactions of protein binding of lidocaine by inhaled anesthetics (halothane, enflurane, isoflurane and sevoflurane in vitro and in vivo. In the in vitro study, no significant changes of protein binding ratio were observed between the controls and any concentrations of the inhaled anesthetics even under high concentration (10 MAC). However, the percent of protein binding was inversely related to the total plasma lidocaine concentration. At lidocaine concentrations of 2, 5 and 9 micrograms.ml-1, the binding ratios were 66.37 +/- 5.36 (%), 55.58 +/- 4.38(%) and 51.66 +/- 4.12(%) respectively. By regression analysis (in vivo), the following relationship was obtained. Y = -0.66X +/- 57.4 (Y: % of protein binding fraction, X: lidocaine concentration). In terms of lidocaine protein binding, there seems to be no hazard in using lidocaine with any inhaled anesthetics.