EMIT antiepileptic drug assays adapted to an Abbott-VP Analyzer and compared with a gas-chromatographic procedure.

The Abbott-VP Bichromatic Analyzer was used for the determination of four antiepileptic drugs (phenobarbital, phenytoin, carbamazepine, primidone) in serum by means of a modified EMIT homogeneous enzyme immunoassay procedure. The main objective of the work was to examine the precision and the accuracy of the results obtained with this system and its cost effectiveness in comparison to the manual method. Day-to-day precision for all four drugs is excellent with coefficients of variation averaging around 5% in the therapeutic range of concentrations. Results for sera analyzed by this procedure and by a gas chromatographic method do not show any significant difference for phenytoin and phenobarbital. There are however slight differences between the two methods for carbamazepine and primidone. These small differences do not modify significantly the clinical interpretation of the results. The procedure is simple and rapid, and requires only one third of the reagents needed in the recommended manual EMIT procedure using the Gilford Stasar III, thus greatly reducing the operation costs.