Influence of premedication on lignocaine-induced acute toxicity and plasma concentrations of lignocaine.

The effects were studied, in eight healthy volunteers, of premedication with diazepam 0.14 mg kg-1 by mouth or hyoscine 6 micrograms kg-1 + morphine 0.2 mg kg-1 i.m., or no premedication, on toxic symptoms and plasma concentrations after rapid i.v. injection of lignocaine 1 mg kg-1. The alpha 1-acid glycoprotein (AAG) and albumin plasma protein fractions were assessed. A variety of mild central nervous system (CNS) symptoms were experienced after the bolus of lignocaine. However, there was no correlation between premedication and degree of severity or number of CNS symptoms. The highest single arterial plasma concentration of lignocaine was 11.0 micrograms ml-1, 1 min after injection. There was no correlation between plasma concentration of lignocaine and occurrence of CNS symptoms. Furthermore, there was no correlation between AAG or albumin plasma concentrations and lignocaine plasma concentrations.