Benzodiazepines and Sedative–Hypnotics in Blood of Drivers Under the Influence and Their Association With Other Common Illegal Drug Use and National Sales Figures

Abstract

The authors examined benzodiazepine and sedative-hypnotic positive cases of drivers under the influence (DUI) in Finland from 1997 to 2008. Factors studied were the number of cases positive for the most commonly encountered of these pharmaceuticals, simultaneous use of amphetamine and/or cannabis, and the relationship between the number of DUI cases and overall sales in Finland for the individual pharmaceuticals. Data for 20037 cases positive for the relevant drugs were retrieved from the laboratory database of the Alcohol and Drug Analytics Unit, National Institute for Health and Welfare. Toxicological results were from blood analysis. Drug sales figures for each pharmaceutical were obtained from the Finnish Medicines Agency. An increase in DUI cases that were positive for the drugs studied was evident, which reflected the overall increase in positive DUI cases detected annually. The proportion of relevant cases was typically 75% or higher of all positive DUI cases up to 2003, the year that the Finnish zero tolerance law was introduced, and then decreased to 66.2% in 2008. Diazepam was consistently the most commonly detected nonmetabolite drug. The prevalence of clonazepam and alprazolam increased sharply from 2004 onward. Metabolites of diazepam, nordiazepam, temazepam, and oxazepam, were other common findings. Associated use of amphetamine and/or cannabis was also common in these DUI cases, typically between 56% and 66% of cases. An increase in the number of DUI cases showing combined use of benzodiazepines and sedative-hypnotics with amphetamines in particular was apparent after zero tolerance legislation and the introduction in 2005 of an effective on-site screening device for the stimulant. Ratios of DUI cases to sales figures showed an increase in detection of clonazepam-positive DUI cases from 2003. Diazepam, midazolam, and alprazolam also exhibited relatively high ratios, which increased from 1997 to 2008.