Comparison of urine and oral fluid as matrices for screening of thirty-three benzodiazepines and benzodiazepine-like substances using immunoassay and LC-MS(-MS).

Benzodiazepines are the most frequently detected medicinal drugs in drivers. The use of benzodiazepines is associated with an increased road accident risk. In this study, the presence of benzodiazepines detected by liquid chromatography-(tandem) mass spectrometry [LC-MS(-MS)] in oral fluid and urine samples obtained from drivers stopped during a roadside survey was compared. In addition, the sensitivity and selectivity of enzyme multiplied immunoassay technique (EMIT II Plus) relative to LC-MS(-MS) was determined for both matrices. A total number of 1,011 urine samples were collected and screened for benzodiazepines using immunoassay (IA) (EMIT II Plus; cutoff 300 ng/mL). In the IA-positive (n = 25) and a group of randomly selected negative urine samples (n = 79), the presence or absence of benzodiazepines was confirmed by LC-MS-MS after deglucuronidation. The corresponding oral fluid samples (n = 101, 3 samples omitted), were analyzed by LC-MS(-MS) and IA (EMIT II Plus; cutoff 10 ng/mL). The presence of benzodiazepines was demonstrated by LC-MS-(MS) in all IA-positive urine samples, but in only four corresponding oral fluid samples. Concentrations in oral fluid were, one substance excepted, lower than in urine. The sensitivity and specificity of EMIT II Plus were better by using urine as matrix for screening of benzodiazepines than by using oral fluid. The results show that benzodiazepines are detectable in oral fluid. More research has to be done to determine the pharmacokinetic profile of the different benzodiazepines in oral fluid and to study the relationship between dose, concentration (in oral fluid and blood), and impairment.