[Cross-reactivity of Instant-View M-1 for detection of benzodiazepine-related drugs and their metabolites in urine].

Immunoassays are useful methods for the determination of regulated drugs in clinical and forensic laboratories. Although the Instant-View M-1 (IV M-1) immunoassay kit is frequently used to screen drugs in laboratories in Japan, basic information about the IV M-1 such as its specificity and reactivity is not available. In this study, we determined the specificity and cross-reactivity of IV M-1 for the detection of benzodiazepine-related drugs and their metabolites in urine. The IV M-1 could detect triazolobenzodiazepines such as triazolam in urine at concentrations > or = 300 ng/mL. However, thienodiazepines such as etizolam could not be detected because of lack of cross reactivity. A correlation was observed between the structure of the metabolites and the reactivity of the kit; 4-hydroxy metabolites of alprazolam and triazolam were detectable, whereas a-hydroxy metabolites were not. Furthermore, 7-amino metabolites such as nitrazepam could not be detected at any concentration, including high concentrations. The specificity and reactivity of various kits used for detection of drugs in urine are different. Therefore, it is necessary to consider the basic features of the kit used while assessing the results obtained.