Alprazolam, d-Amphetamine, Codeine, and Marijuana

The Drug Evaluation and Classification (DEC) program is used by police agencies to identify drivers impaired because of drug use and to determine the class(es) of drug causing the impairment. The primary goal of this study was to determine the validity of the DEC evaluation in predicting whether research volunteers were administered alprazolam, d-amphetamine, codeine, or marijuana. A secondary goal was to determine the accuracy of Drug Recognition Examiners (DREs) in detecting if subjects were dosed with these drugs. Community volunteers (n = 48) were administered alprazolam (0, 1, 2 rag), d-amphetamine (0, 12.5, 25 rag), codeine (0, 60, 120 rag), or marijuana (0, 3.58% THC) in a double-blind, randomized, between-subject design. A single drug dose or placebo was administered at each experimental session, and blood samples were obtained before and after dosing. With the exception of marijuana, plasma drug concentration was at or near maximum during the DEC evaluation. The ability of the DEC evaluation to predict the intake of alprazolam, d-amphetamine, codeine, or marijuana was optimal when using 2-7 variables from the evaluation. DREs' decisions of impairment were consistent with the administration of any active drug in 76% of cases, and their drug class decisions were consistent with toxicology in 32% of cases, according to standards of the International Association of Chiefs of Police. These findings suggest that the DEC evaluation can be used to predict accurately acute administration of alprazolam, d-amphetamine, codeine, and marijuana and that predictions of drug use may be improved by focusing on a subset of variables.