First experience with the REMEDi HS urine benzodiazepine assay

Ninety eight urine samples were analysed with an immunoassay benzodiazepine kit. A total of 68 urine specimens that were presumptively positive for benzodiazepines were evaluated by the REMEDi HS urine benzodiazepine assay (BIO-RAD, Munich, Germany). Of this number, 53 (78%) specimens were found by REMEDi to contain one or more benzodiazepines or their metabolites, and 15 (22%) were found to be negative. From the discordant group of 15 samples, eight were found to be negative using conventional chromatographic procedures (HPLC or GC/MS), while seven contained one or more benzodiazepines or metabolites, each of which were below the individual cut-off level specified by the manufacturer. Additionally 30 urine specimens that were negative for benzodiazepines using immunoassay were also tested by REMEDi. Two samples were found to be positive. These results could not be confirmed by other chromatographic techniques. The REMEDi HS benzodiazepine assay can be a very useful complementary technique in the clinical/forensic toxicology laboratory, especially for the identification of the parent benzodiazepines administered. The assay provides a rapid result in emergency situations and is useful in confirmation of preliminary positive immunoassay results.