Toxicological and Demographic Profiles of Phencyclidine-Impaired Driving Cases in Houston.

Phencyclidine (PCP) was first synthesized in 1926 and originally developed in 1950s as a general anesthetic agent. Abuse of PCP declined at the national level since its first illicit use in 1960s, but it continues in certain areas including Houston. This research evaluates PCP-positive cases of driving while intoxicated (DWI) in 2013-2018. The blood samples were collected from drivers, submitted by the Houston Police Department and analyzed for alcohol and drugs. Toxicological findings and demographic information were evaluated for the impaired driving cases tested positive for PCP in blood. Additionally, the Drug Recognition Expert (DRE) findings were examined for 12 cases in 2018. A total of 615 DWI cases positive for PCP in blood were identified in which the traffic offense occurred between August 2013 and December 2018. The mean (median, range) PCP concentration was 47 (43, 7-180) ng/mL. A total of 23% of those cases were females, and 77% were males; 85% were blacks, 10% were whites and 5% were other races/ethnicities as identified by the arresting officer. The mean age was 37 years. No significant differences in median and distribution of PCP concentrations (P's > 0.05) were observed across the offense years and among demographic cohorts. A total of 43% of the cases were positive for PCP only. Among the remaining 57%, cannabinoids are the most common concurrently detected analytes (35%), followed by cocaine/metabolite (14%) and ethanol (13%). The proportion of black male PCP-positive drivers decreased in younger age groups. Common indications observed by DRE officers included slurred speech, chemical breath odor, watery and/or bloodshot eyes, vertical/horizontal gaze nystagmus and impaired coordination/balance. This study provides valuable regional information to better understand the demographic patterns of PCP-impaired drivers in Houston, TX over 6 years. The findings may aid in designing and implementing regulations and prevention programs to reduce PCP-impaired driving.