An Experimental Study of Diazepam and Alprazolam Kinetics in Urine and Oral Fluid Following Single Oral Doses

J Anal Toxicol. 2019 Mar 1;43(2):104-111. doi: 10.1093/jat/bky062.


Benzodiazepines are commonly seen in samples submitted for drug testing of patients, people involved in child welfare cases, work-place drug testing, as well as in drug-facilitated assaults. Limited previous experimental studies are available regarding the excretion of benzodiazepines in urine and oral fluid. The aim of this study was to investigate the concentrations of diazepam and alprazolam in oral fluid and urine for up to 2 weeks after ingestion of a single oral dose in healthy volunteers. A total of 11 healthy volunteers ingested 10 mg diazepam at the start of the study and 0.5 mg alprazolam on Day 3 of the study. A total number of 10 oral fluid samples and 17 urine samples were collected from each participant. The samples were analyzed by liquid chromatography with tandem mass spectroscopy and ultra-high performance liquid chromatography tandem mass spectrometry methods. The median detection time was 252 h for the longest detected diazepam metabolite in urine (oxazepam, range 203-322) and 132 h in oral fluid (N-desmethyldiazepam, range 109-136). For alprazolam, the median detection time was 36 h (metabolite α-OH-alprazolam, range 26-61) in urine and 26 h (alprazolam, range 4-37) in oral fluid. These results show that detection times are only 36 h for alprazolam in urine after intake of a single therapeutic oral dose. For diazepam in urine, detection times were 11 days. Detection times were generally shorter in oral fluid compared to urine. The results could be helpful in the interpretation of diazepam or alprazolam findings in drug testing cases involving urine or oral fluid.

MeSH terms

  • Administration, Oral
  • Adult
  • Alprazolam / analysis
  • Alprazolam / urine*
  • Diazepam / analysis
  • Diazepam / urine*
  • Female
  • Healthy Volunteers
  • Humans
  • Kinetics
  • Male
  • Saliva / chemistry*
  • Time Factors
  • Young Adult


  • Diazepam
  • Alprazolam