Unusually High Concentration of Fentanyl in a Driver: A Case Report.

A driving under the influence of drugs (DUID) case with an extremely high blood fentanyl concentration and concomitant use of methamphetamine is presented. As the increase of the appearance of fentanyl in drug seizures continues, the likelihood of tolerant users increases as well. Data presented on fentanyl in ante-mortem cases over time from several regions of North America show geographic differences on whether fentanyl concentrations are increasing. This case is an example of a blood concentration that could have been assumed to be fatal if presented on its own; a reminder that concentrations, especially those of opioids, must be interpreted with care.