Urine Monitoring of Diazepam Abuse—New Intake or Not?

Abstract

Testing for drugs-of-abuse in urine is requested for multiple reasons, including legal and workplace policies. Two cases were studied in which there was a suspicion that the patients continued to abuse diazepam, because of repeatedly positive urine samples. In these cases, diazepam metabolites were measured in urine samples by gas or liquid chromatography coupled to mass spectrometry. The concentrations of diazepam metabolites were subsequently creatinine correlated. Very long elimination times were found in the described cases. None of them had in fact ingested diazepam again during the study period. By the use of pharmacogenetic typing, one of the subjects was found to have a slow metabolism for CYP2C9 as well as for CYP2C19. In the second case, there was a possible drug interaction between diazepam and zolpidem.