1. Self reported (il)licit drug use in Belgian drivers Trudy Van der Linden a, Peter Silverans b, Cristina Isalberti a, Sara-Ann Legrand a, Alain Verstraete a a Department of Clinical Chemistry, Microbiology and Immunology, Ghent University, De Pintelaan 185, 9000 Ghent, Belgium b Belgian Road Safety Institute, Haachtsesteenweg 1405, 1130 Brussel Introduction: There are relatively few data on the prevalence of driving under the influence of drugs in the general population. Within the DRUID project, an epidemiological study was conducted, collecting oral fluid with the StatSure TM Saliva Sampler TM during road side surveys. Aim: The purpose of this study was to compare the number of drivers who reported to have taken drugs and/or medicines with the results of toxicological analysis of an oral fluid sample. Results: Table 2 shows for each time category the number of subjects who self reported use on the left, and on the right the number of samples that were found positive for each drug class. Figure 3 shows the relationship between the time after intake and the ratio of positive toxicological result vs self-reported use. Conclusion: Alcohol, antidepressants, cannabis, benzodiazepines and codeine were most commonly used. According to self report most drugs were last taken 4h or more before driving. Self-report yielded more positives than toxicological analysis. As expected the percentages of positives were higher among subjects who reported more recent drug consumption. Disclaimer: This abstract has been produced under the project “Driving Under the Influence of Drugs, Alcohol and Medicines” (DRUID) financed by the European Commission within the framework of the EU 6th Framework Program. This abstract reflects only the author's view. The European Community is not liable for any use that may be made of the information contained therein. Drug ClassSelf-reported use/ total toxicological findings Self reported use (hours before sampling) / positive toxicological results <1h < 4h < 12h < 24h > 24h unknown Alcohol 1614/196 138/95180/54 182/15 370/9 713/14 31/7 Antidepressants 110/41 6/314/5 50/19 24/8 8/0 8/6 Benzodiazepines and Z-drugs 98/40 4/210/9 33/14 30/9 12/4 9/2 Cannabis 79/32 5/43/1 10/8 7/3 46/14 8/2 Codeine 60/6 4/27/3 9/0 6/0 25/0 9/1 Cocaine 7/5 2/20 0 0 4/2 1/1 Amphetamine 5/2 00 0 0 3/1 2/1 Heroin 2/1 1/10 0 0 1/0 0 Method: 2957 respondents driving a personal car or van completed a questionnaire during roadside surveys to report their use of drugs and medicines during the last two weeks and indicate the time of last intake. The drug classes were combined into benzodiazepines and Z- drugs, antidepressants, codeine, alcohol, cannabis, cocaine, heroin and amphetamines. Drugs were analysed in oral fluid by UPLC-MS/MS. Frequencies in the time categories were calculated and compared with toxicological results. Toxicological analysis: The oral fluid samples were collected using StatSure TM Saliva Sampler TM device. This consists of an absorptive pad with a volume indicator that turns blue when 1 mL of oral fluid has been collected, and a plastic tube containing 1 mL of buffer solution. To account for any possible variability in the volume of oral fluid collected, drug concentrations obtained after UPLC-MS/MS analysis were corrected on the basis of the average weight of an empty StatSure TM device and the weight of the StatSure TM device after sample collection. For the liquid liquid extraction. 20 µL of 200 ng/mL isotope-labelled internal standards solution and 200 µL of NH 4 HCO 3 (0.2 M, pH 9.3) were added to 400 µL of sample. Samples were then extracted with 1.25 mL of heptane/ethyl acetate (1:4). After 15 minutes on a shaker and centrifugation, the organic phase was transferred into a clean test tube and evaporated to dryness at room temperature. Samples were reconstituted in 100 µL methanol/water (50:50) and transferred into a vial for UPLC-MS/MS analysis. UPLC-MS/MS analysis was performed on an Acquity TM ultra performance liquid chromatograph (Waters) equipped with an Acquity UPLC BEH C18 column (1.7µm, 2.1 x 100mm) and a Vanguard BEH C18 pre-column (1.7µm, 2.1 x 5mm). Detection was performed using a Waters Quattro Premier XE tandem mass spectrometer operating in MRM mode. [1] All samples were also analysed for ethanol using the Ethanol Gen.2 enzymatic method on a Roche Cobas Integra 400 system. Analytes measured and cut-offs used are presented in the Table 1. Distinction between heroin and codeine use was based on the following equations: - codeine concentration ≤ morphine concentration  heroin use - codeine concentration > morphine concentration  codeine use Figure 1: roadside survey team Figure 2: StatSure TM Saliva Sampler TM Discussion: Volunteers reported all type of alcohol use, also of small amounts that could result in saliva concentrations below the cut-off at the time of sampling. For alcohol, the ratio of self reported use versus toxicological findings decreases over time, reflecting the normal kinetics of alcohol elimination. For antidepressants the ratio appears to be more constant over the 24 hours. This pattern is in good agreement with a long-term therapy, aiming to achieve a steady state concentration. It has to be noted that toxicological analysis did not screen for all the antidepressants available on the market. Several subjects reported use of antidepressants such as paroxetine and venlafaxine, that were not included in the toxicological screening, and this may explain why the ratio between self reported use and toxicological findings is low. As for benzodiazepines and Z-drugs, peak plasma concentrations of the substances analysed for lay between 1 and 4 hours after intake, which could explain the ratio peaking at <4h and an apparent steady state after 12h (the wide range of half-life for the drugs analysed has to be considered). Concentrations of THC depend on dose and type of use (occasional or chronic). Also, after cannabis inhalation, contamination of THC in the oral cavity can appear. These facts may explain the rather irregular pattern of the ratio between self reported use and toxicological findings in the first hours, and a declining trend after 12 hours, as expected with plasma concentrations. For codeine the pattern that emerges is likely to suggest and occasional use, maybe at low dose in combination with paracetamol, as it is with the consumption of cold medicines. Table 1: Analytes and DRUID cut-offs Table 2: Self reported use/positive toxicological result per time category Figure 3: Time after intake vs ratio positive tox result/self reported use References: [1] Goessaert et al. (2010) Anal Bional chem 396 (7): 2461-8