単回摂取後のエチゾラムおよび主要代謝物の尿中排泄プロファイル

抄録

 In this study, the excretion profiles of etizolam (EZ) and its main metabolites including conjugates in urine have been investigated to obtain fundamental information for proving the drug intake in the cases of drug-related crimes. Urine specimens were collected from three volunteers during about 200 h after a single oral ingestion of EZ (1 mg). Three glucuronides (including diastereomers) of 8-α-hydroxyetizolam (EZ-M3) and 1-hydroxyetizolam (EZ-M6) along with free EZ-M3 and EZ-M6 were detected for the first time directly as metabolites of EZ using liquid chromatography-tandem mass spectrometry with a C18 semi-micro column. EZ, EZ-M3 and EZ-M6 were quantified using the authentic standards, and urinary concentrations of the glucuronides were calculated based on the increased amounts of EZ-M3 and EZ-M6 after enzymatic hydrolysis. The quantitative results demonstrated that the ratios of amounts of EZ-M3 and EZ-M6 including their glucuronides excreted in urine to the dose ranged about 18-22% and 9.5-14%, respectively, although that of the unchanged EZ was less than 0.3%. The glucuronide of EZ-M6 reached the highest concentration (more than 200 ng/mL) of metabolites in the early period (within 12 h) after intake. However, in a latter period (24 h or later) after intake, the concentration of EZ-M3 or its glucuronides was higher than that of glucuronide of EZ-M6 in most of the samples. The conjugation percentages of EZ-M3 and EZ-M6 were calculated to be approximately 50% and 98% or higher, respectively. This study suggested that the detectable duration of EZ-M3 (approximately one week after intake, Limit of detection: 0.05 ng/mL) is longer than those of EZ and EZ-M6. In addition, the enzymatic hydrolysis prior to analysis is expected to prolong the detectable duration of EZ-M3 slightly.