GLC assay for lidocaine in human plasma.

A simple, rapid, and highly sensitive method for the GLC analysis of plasma lidocaine is described. Mepivacaine hydrochloride is added as the internal standard; the plasma is deproteinated and centrifuged, and the supernate is alkalinized and extracted into a small volume of carbon disulfide. The column is connected to a flame-ionization detector, and the column oven temperature is programmed from 130 to 260 degrees. Plasma lidocaine concentrations between 0.04 and 8.0 micrograms/ml can be measured accurately, and there is no interference from the monoethylglycinexylidide or glycinexylidide metabolites of lidocaine or from many commonly used drugs and diagnostic agents. The sensitivity, simplicity, and speed of this assay are important in pharmacokinetic studies of lidocaine.