Carfentanil Blood Concentrations in Impaired Driving Investigations in Ontario, Canada.

Carfentanil is a potent opioid with no medical use in humans; it presents a serious threat to public health and road safety due to its presence in the illicit drug supply, the potency of the drug and instances of use prior to the operation of a motor vehicle. The identification and quantitation of carfentanil using liquid chromatography with tandem mass spectrometry was performed in blood samples obtained through impaired driving-related investigations from 2017 to 2019. In a series of 66 cases submitted to the Centre of Forensic Sciences in Ontario, Canada, blood concentrations of carfentanil ranged from <0.04 to 2.1 ng/mL in the population studied. Driving behaviors frequently came to the attention of concerned citizens, decreased levels of consciousness were commonly reported and a variety of medical interventions were required, in some cases, to preserve life due to apparent opioid toxicity.