Relationship between oral fluid and blood concentrations of drugs of abuse in drivers suspected of driving under the influence of drugs.

In recent years, the interest in the use of oral fluid as a biological matrix has increased significantly, particularly for detecting driving under the influence of drugs (DUID). In this study, the relationship between the oral fluid and the blood concentrations of drugs of abuse in drivers suspected of DUID is discussed. Blood and oral fluid samples were collected from drivers suspected of DUID or stopped during random controls by the police in Belgium, Germany, Finland, and Norway for the ROSITA-2 project. The blood samples were analyzed by gas chromatography-mass spectrometry (GC-MS) or liquid chromatography-mass spectrometry (LC-MS), sometimes preceded by immunoassay screening of blood or urine samples. The oral fluid samples were analyzed by GC-MS or LC-MS(/MS). Scatter plots and trend lines of the blood and oral fluid concentrations and the median, mean, range, and SD of the oral fluid to blood (OF:B) ratios were calculated for amphetamines, benzodiazepines, cocaine, opiates, and Delta(9)-2 tetrahydrocannabinol. The ratios found in this study were comparable with those that were published previously, but the range was wider. The OF:B ratios of basic drugs such as amphetamines, cocaine, and opiates were >1 [amphetamine: median (range) 13 (0.5-182), methylenedioxyamphetamine: 4 (1-15), methylenedioxymethamphetamine: 6 (0.9-88), methamphetamine: 5 (2-23), cocaine: 22 (4-119), benzoylecgonine: 1 (0.2-11), morphine: 2 (0.8-6), and codeine: 10 (0.8-39)]. The ratios for benzodiazepines were very low, as could be expected as they are highly protein bound and weakly acidic, leading to low oral fluid concentrations [diazepam: 0.02 (0.01-0.15), nordiazepam: 0.04 (0.01-0.23), oxazepam: 0.05 (0.03-0.14), and temazepam: 0.1 (0.06-0.54)]. For tetrahydrocannabinol, an OF:B ratio of 15 was found (range 0.01-569). In this study, the time of last administration, the dose, and the route of administration were unknown. Nevertheless, the data reflect the variability of the OF:B ratios in drivers thought to be under the influence of drugs. The wide range of the ratios, however, does not allow reliable calculation of the blood concentrations from oral fluid concentrations.

Usefulness of roadside urine drug screening in drivers suspected of driving under the influence of drugs (DUID).

In Belgium, the driving under the influence of drugs (DUID) procedure consists of three steps: observation of external signs of drug consumption by a police officer; an on-site urine test for amphetamines, cannabinoids, cocaine, and opiates; and blood sampling by a physician for gas chromatography-mass spectrometry analysis. The driver is sanctioned if THC is greater than 2 ng/mL, morphine is greater than 20 ng/mL, or amphetamine, methylenedioxymethamphetamine (MDMA), methylenedioxyethylamphetamine, N-methyl-1-(3.4-methylenedioxyphenyl)-2-butanamine, cocaine, or benzoylecgonine are greater than 50 ng/mL in plasma. We analyzed the results of 450 blood samples taken from May 2000 to February 2005. Cannabis was most often found above the cut-off (73.5% of the cases), followed by MDMA (20.4%), amphetamine (19.8%), benzoylecgonine (17.9%), cocaine (6.9%), and morphine (2.7%). One drug was found in 72.0% of the cases, two drugs in 22.6%, three drugs in 5.2%, and four drugs in 0.25%. In 10.7% of the plasma samples no target drugs were found above the legal cut-off. This percentage was 8.4% when urine was obtained and tested on-site and 21.2% when no urine was obtained (chi2 = 8.574, P = 0.0034). In 64.6% of these samples, a target drug (THC in 74.2%) was found under the legal cut-off. These data indicate that roadside urine testing significantly decreases the number of unnecessary blood analyses in DUID.