Lidocaine by Enzyme Immunoassay

The cardioactive drug lidocaine was measured by a homogeneous enzyme immunoassay procedure (EMIT ®) using a procedure similar to the one described for the determination of antiepileptic drugs in serum. The assay requires 50 µl of serum per determination and less than 5 minutes to perform. The assay is specific for lidocaine and does not cross-react with lidocaine metabolites or other cardioactive drugs. Twenty replicate analyses of a serum containing lidocaine gave a CV of 3.4%. Results attained with a large series of patients administered lidocaine alone or with other cardioactive drugs were compared with results by a gas liquid chromatographic procedure. The correlation coefficient (r) was 0.976. No false postives or negatives were encountered.