Norwegian patients in methadone assisted treatment programs (MATP) are allowed to drive after at least 6 months on an unchanged daily dose. The number of patients in MATP has increased more than ten fold since 1997. By using the nationwide database of the National Institute of Forensic Toxicology on blood concentrations measured in suspected drugged drivers during 1997-2001, all methadone positive cases were identified. These cases had been subject to blood alcohol and drug screening with confirmation and quantification of methadone and other drugs present. These results were used in the present study. The number of suspected drugged driving cases was approximately 3000-4000 per year for the study period, while methadone positive cases increased steadily from 3 in 1997 to 69 in 2001. In most cases from 2000-2002 the blood methadone concentrations measured were compatible with daily dosing up to 150 mg, i.e. within the therapeutic range. In 97% of the cases additional drugs were detected. Flunitrazepam was present in 72% of the samples, often in high concentrations and other benzodiazepines were also abundant, as were tetrahydrocannabinol and amphetamine. Recent heroin use could be stated (6-monoacetyl-morphine positive) in 17%, and was suspected in additional 18% of the cases. As a mean between 2 and 3 additional drugs were found in methadone positive samples. Drivers on methadone, suspected of drugged driving, have a more frequently use of additional drugs than has been reported from MATP with urine drug control. This might suggest that those on methadone who also use additional drugs, more likely become impaired and consequently drive in a manner calling attention from the police. (Author/publisher) For the covering abstract of the conference see ITRD Abstract No. E201067.
Abstract