Detection of 4 benzodiazepines in oral fluid as biomarker for presence in blood.
BACKGROUND
Analysis of samples of oral fluid (mixed saliva) is increasingly being used to detect recent drug use. The aim of this investigation was to assess the suitability of testing oral fluid as a biomarker for the presence of 4 benzodiazepines in blood and its possible application in clinical settings and in research on drug use.


METHODS
Paired samples of oral fluid and blood from 4080 individuals in 4 European countries were collected and analyzed for benzodiazepines using gas or liquid chromatography with mass spectroscopic detection.


RESULTS
Concentration data for the 4 most commonly detected benzodiazepines were studied: alprazolam, clonazepam, diazepam, and nordiazepam. Large variations in oral fluid to blood concentration ratios were observed for the studied benzodiazepines. The interquartile ranges for the oral fluid to blood concentrations ratios corresponded to 88%-197% of the median values. Selecting cutoff concentrations in oral fluid that gave the best accuracy in identifying individuals with benzodiazepine concentrations in blood above chosen thresholds produced accuracies of 74%-85% and the fraction of false negatives was 9%-23%.


CONCLUSIONS
The concentration of the 4 studied benzodiazepines in oral fluid can neither be used to accurately estimate the concentrations in blood nor to correctly identify patients with blood drug concentrations below or above recommended therapeutic levels. When using analytical methods with limits of quantitation corresponding to concentrations less than 0.5 ng/mL in undiluted oral fluid, it may be used to confirm a recent intake of benzodiazepines. However, it is likely that some false negatives may occur.
*Division of Forensic Medicine and Drug Abuse Research, Norwegian Institute of Public Health, Oslo, Norway; †Department of Alcohol, Drugs, and Addiction, National Institute for Health and Welfare, Helsinki, Finland; ‡School of Medicine, Department of Molecular Medicine, Forensic Toxicology and Antidoping, University of Padova, Italy; and §Department of Clinical Chemistry, Microbiology and Immunology, Ghent University and Laboratory of Clinical Biology, Ghent University Hospital, Belgium.
Hallvard
H
Gjerde
Kaarina
K
Langel
Donata
D
Favretto
Alain G
AG
Verstraete
D001569:Benzodiazepines / Q000032:analysis* / Q000097:blood*; D015415:Biomarkers / Q000032:analysis / Q000097:blood; D002853:Chromatography, Liquid; D005188:False Negative Reactions; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D015203:Reproducibility of Results; D012463:Saliva / Q000737:chemistry*; D015813:Substance Abuse Detection / Q000379:methods*
D015415:Biomarkers; D001569:Benzodiazepines