Persistent Urinary Benzoylecgonine Following Cocaine Use

Abstract

The authors examine the utility of a fluorescence polarization immunoassay (the ADx Cocaine Metabolite Assay) for the determination of benzoylecgonine in 41 patients (28 women and 13 men) admitted to an inpatient substance abuse treatment unit following recent cocaine use. The assay remained positive (i.e., exceeded 300 ng/ml) in urine for a mean of 84.4 hours from the last reported use. There was no difference by gender or route of administration either for grams used or hours of positivity. Cocaine use in the week prior to admission was the only significant predictor of hours of positivity; age, gender, and weight did not contribute significantly to the variance. The implications of these findings for both cocaine pharmacokinetics and for treatment of cocaine abuse are discussed.