SIMPLIFIED QUANTITATION OF URINARY BENZOYLECGONINE IN COCAINE ADDICTION RESEARCH AND FOR RELATED PHARMACOTHERAPEUTIC TRIALS

In clinical trials of potential pharmacotherapies for cocaine addictio n, objective determination of subject relapse relies on qualitative ur ine analysis for benzoylecgonine, the major metabolite of cocaine. Unl ike qualitative analysis, quantitative measurement allows differentiat ion between continued cocaine use and a single use, as well as identif ication of changes in the quantity of cocaine used at different times. The only quantitative technique that has been used is expensive and n ot generally feasible. This study was performed to modify an existing qualitative technique for use as a new simple and readily available qu antitative method for identifying cocaine use among research subjects. Benzoylecgonine levels in 24-hour urine specimens collected from 11 c ocaine-addicted subjects hospitalized in a research setting were measu red semi-quantitatively by fluorescence polarization immunoassay. Accu rate results required thorough mixing of urine specimens prior to anal ysis. Ar admission, eight subjects had urinary benzoylecgonine levels greater than or equal to 0.30 mu g/ml, the standard positive/negative cut-off used in qualitative analysis. The mean half-life of benzoylecg onine during initial elimination was 0.46 +/- 0.08 (SEM, n = 8) days. Benzoylecgonine (BE)/creatinine (C) levels remained greater than or eq ual to 0.30 mu BE/mgC for 4.8 +/- 0.5 (n = 8) days and greater than or equal to 0.03 mu gBE/mgC for 10.5 +/- 1.5 (n = 8) days. Relapses in t hree subjects could be identified by quantitative analysis. This study indicates that quantitation of benzoylecgonine in daily urine specime ns provides a sensitive, objective index to cocaine use.