Maren Cecilie Strand1, Jørg Mørland2, Lars Slørdal3, Bettina Riedel4, Cato Innerdal5, Trond Aamo6, Grete Mathisrud7, Vigdis Vindenes8. 1. Oslo University Hospital, Department of Forensic Medicine, Oslo, Norway. Electronic address: macest@ous-hf.no. 2. Norwegian Institute of Public Health, Division of Health Data and Digitalization, Oslo, Norway. Electronic address: jomo@fhi.no. 3. Department of Laboratory Medicine, Children's and Women's Health, Norwegian University of Science and Technology, Trondheim, Norway; Department of Clinical Pharmacology, St. Olav University Hospital, Trondheim, Norway. Electronic address: lars.slordal@ntnu.no. 4. University of Bergen, Faculty of Medicine and Dentistry, Department of Clinical Science, Bergen, Norway; Haukeland University Hospital, Laboratory of Clinical Biochemistry, Bergen, Norway. Electronic address: bettina.riedel@helse-bergen.no. 5. Public Health Officer Molde, Norway. Electronic address: cato.innerdal@molde.kommune.no. 6. Department of Clinical Pharmacology, St. Olav University Hospital, Trondheim, Norway. Electronic address: trond.aamo@legemidler.no. 7. Norwegian Ministry of Transport and Communications, Department of Public Roads and Traffic Safety, Oslo, Norway. Electronic address: Grete.Mathisrud@sd.dep.no. 8. Oslo University Hospital, Department of Forensic Medicine, Oslo, Norway; Center of Drug and Addiction Research, Faculty of Medicine, University of Oslo, Norway. Electronic address: vigvin@ous-hf.no.
Abstract
AIMS: Norway has introduced legal concentration limits in blood for 28 non-alcohol drugs in driving under the influence cases. As of 2016 this legislation also regulates the assessment of combined effects of multiple benzodiazepines and opioids. We herein describe the employed methodology for the equivalence tables for concentrations of benzodiazepines/z-hypnotics and opioids implemented in the Norwegian Road Traffic Act. METHODS: Legislative limits corresponding to impairment at blood alcohol concentrations (BAC) of 0.02%, 0.05% and 0.12% were established for 15 different benzodiazepines and opioids. This was based on a concept of a linear relationship between blood drug concentration and impairment in drug naïve users. Concentration ratios between these drugs were used to establish conversion factors and calculate net impairment using diazepam and morphine equivalents. RESULTS: Conversion factors were established for 14 benzodiazepines/z-hypnotics (alprazolam, bromazepam, clobazam, clonazepam, etizolam, flunitrazepam, lorazepam, nitrazepam, nordiazepam, oxazepam, phenazepam, temazepam, zolpidem and zopiclone) and two opioids (methadone and oxycodone). CONCLUSIONS: Conversion factors to calculate diazepam and morphine equivalents for benzodiazepines/z-hypnotics and selected opioids, respectively, have been operative in the Norwegian Road Traffic Act as of February 2016. Calculated equivalents can be applied by the courts to meter out sanctions.
AIMS: Norway has introduced legal concentration limits in blood for 28 non-alcohol drugs in driving under the influence cases. As of 2016 this legislation also regulates the assessment of combined effects of multiple benzodiazepines and opioids. We herein describe the employed methodology for the equivalence tables for concentrations of benzodiazepines/z-hypnotics and opioids implemented in the Norwegian Road Traffic Act. METHODS: Legislative limits corresponding to impairment at blood alcohol concentrations (BAC) of 0.02%, 0.05% and 0.12% were established for 15 different benzodiazepines and opioids. This was based on a concept of a linear relationship between blood drug concentration and impairment in drug naïve users. Concentration ratios between these drugs were used to establish conversion factors and calculate net impairment using diazepam and morphine equivalents. RESULTS: Conversion factors were established for 14 benzodiazepines/z-hypnotics (alprazolam, bromazepam, clobazam, clonazepam, etizolam, flunitrazepam, lorazepam, nitrazepam, nordiazepam, oxazepam, phenazepam, temazepam, zolpidem and zopiclone) and two opioids (methadone and oxycodone). CONCLUSIONS: Conversion factors to calculate diazepam and morphine equivalents for benzodiazepines/z-hypnotics and selected opioids, respectively, have been operative in the Norwegian Road Traffic Act as of February 2016. Calculated equivalents can be applied by the courts to meter out sanctions.