Efficacy of urinalysis in monitoring heroin and cocaine abuse patterns: implications in clinical trials for treatment of drug dependence.

Urinalysis can be used as an objective criterion for monitoring the outcome of a treatment program or a clinical trial. Important factors to consider when implementing a drug testing program include standardization of assay technology and cutoffs between participating centers and selection of identical testing schedules. Also, it is vitally important to minimize the amount of safe time (time that drug use can go undetected) occurring in a testing schedule. The detection times for cocaine and heroin have been shown to vary with selection of cutoff and with the drug dose. Obviously, the selection of cutoffs is under program control, whereas the amount of illicit drug use is under subject control. Fortunately, changes in the illicit drug dose by the subject demonstrate a log-linear relationship to detection time. Hence, a higher drug dose by the subject only extends the detection time slightly (and improves the probability of detection) without greatly increasing the risks of drug carryover from one urine test to another. The most efficient testing schedule for judging the outcome of clinical trials for cocaine and heroin appears to be a 3-days-a-week schedule (Monday, Wednesday, Friday or Tuesday, Thursday, Saturday). When different schedules were challenged by simulating random times at which cocaine use might occur during the week, the 3-days-per-week schedule was the most efficient without the risk of carryover. The 3-days-per-week schedule also performed better than 1-day-per-week when multiple random drug use was simulated. Overall, the 3-days-per-week testing schedule with specified assay technology and cutoffs was the best compromise for maximizing detection of drug use, minimizing carryover, and providing a standardized methodology for outcome comparison between programs.