ENZYME-LINKED-IMMUNOSORBENT-ASSAY FOR DETECTING BENZODIAZEPINES IN URINE

A relatively simple ELISA technique was developed for the detection of a range of benzodiazepines (BZs) in urine. The assay employs a mouse anti-oxazepam antibody that is highly specific for the BZs. The limit of detection using 10 mu l samples of urine was 0.3 mu g ml(-1) oxazep am. N-Desmethyldiazepam showed equal cross-reactivity to oxazepam, 11 BZs cross-reacted weakly and flurazepam and chlordiazepoxide did not c ross-react at levels reported to be found in urine. No cross-reactivit y was observed with drugs of abuse and a range of therapeutic drugs co mmonly found in urine. The assay was used as a screen to detect the pr esence of BZs in urine from gs addicts that had been screened by the E MIT technique and a radioreceptor assay (RRA) for BZs. The ELISA produ ced two false negatives that were EMIT and RRA positive whereas the EM IT produced four different false negatives that were positive by both ELISA and RRA. Thirty-three positives were common to all three assays. The ELISA was also used to monitor nitrazepam-like activity in the ur ine of a greyhound receiving 5 mg oral medication and the results were compared with those obtained by RRA. Both assays were able to detect nitrazepam-like activity for up to 10 h post-administration.