Oxazepam Detected in Urine 79 Days After Withdrawal of Diazepam: A Case Report

Patients suffering from substance use disorder, including for instance benzodiazepines, may have comorbidity with attention deficit hyperactivity disorder (ADHD). Centrally acting stimulants play an important role in the treatment of ADHD. Before such treatment can be initiated, withdrawal of benzodiazepines may be necessary. Urine testing is the preferred method for monitoring adherence in benzodiazepine withdrawal, but there is a lack of studies reporting detection time. Here, we report a case of a 30-year-old woman with substance use disorder and ADHD who had detectable metabolites of diazepam 79 days after withdrawal. To our knowledge, no cases with detection time equivalent to this have previously been published. This case report serves as an example that clinicians may need to consider interindividual pharmacokinetic characteristics when interpreting the results of urine drug tests, and that a positive urine test may still be consistent with abstinence from a certain drug. In the current case, a high body mass index and a genetic polymorphism gave a reasonable explanation for the prolonged detection of diazepam metabolites.