COMPARATIVE-STUDIES ON THE DETECTION OF BENZODIAZEPINES IN SERUM BY MEANS OF IMMUNOASSAYS (FPIA)

Serum was tested for benzodiazepines by fluorescence polarization Immunoassay (FPIA) on Abbott's ADx system using the benzodiazepine serum reagents (Benzo S) and the benzodiazepine urine reagents (Benzo U) after pretreatment of specimens by means of acetone precipitation. The following sera were included for comparing the two methods: Negative sera spiked with various benzodiazepines; 80 sera randomly selected out of a total of 8654 serum specimens from impaired drivers; and blood specimens from individuals who stated that they had taken benzodiazepines. The different benzodiazepines were added to serum at concentrations of 25, 75, and 300 ng/mL. The low-dose benzodiazepines flunitrazepam and triazolam were additionally tested at serum concentrations of 10 ng/mL. Because of the better reproducibility and the shift of the dynamic range to lower concentrations, the Benzo S assay was found to be more sensitive than the Benzo U assay after acetone precipitation. The direct ADx benzodiazepine serum assay has clear advantages over the acetone precipitation method, especially with regard to therapeutic concentrations and for the detection of the highly potent and low-dose benzodiazepines flunitrazepam and triazolam. © 1993 Oxford University Press.