Correlation between fluorescent polarisation immunoassay and enzyme immunoassay of anticonvulsant drugs, and stability of calibration graphs

Abstract

Quality control materials and serum samples from patients on long-term drug therapy were analysed for anticonvulsant drugs by enzyme immunoassay (EMIT) and fluorescence polarisation immunoassay (TDX). The accuracy and precision of the two procedures were studied and the stability of calibration graphs was evaluated over a 30-d period. The accuracy and precision of both assays were satisfactory over the therapeutic ranges of phenobarbitone, primidone, phenytoin and carbamazepine and there was a good correlation between the results obtained by EMIT and TDX; for sodium valproate the accuracy and precision of the EMIT assay were poor. Calibration graphs generated by the TDX procedure were found to be stable, but with the EMIT procedure, calibration graphs for phenobarbitone, carbamazepine and sodium valproate showed considerable drift.