Cocaine Metabolite (Benzoylecgonine) in Hair and Urine of Drug Users

Two methods of drug detection, urinalysis and hair analysis, were compared with respect to the efficiency of identification of drug use in a population of men living on the Arizona-Mexico border. The standard curve of cannabinoids in urine was linear to 20 ng/mL. The GC/MS levels for all cannabinoids combined in urine were very similar to that obtained by radioimmunoassay (RIA), 91% concordance. Similar results were obtained from samples analyzed dually for the cocaine metabolite benzoylecgonine (BE) after spiking. As determined by RIA of urine, 74% of the subjects were positive for cannabinoids. The majority were in the range of 100–1000 ng/mg creatinine. The pattern of excretion of THC metabolites with respect to the verbally reported time of first use was fairly normal, with the peak rate of elimination 13–24 hours following the last reported use. Washed hair samples were extracted by overnight acid hydrolysis. Urine samples and neutralized hair extracts were analyzed for cocaine and BE by RIA. Of the hair samples, 55% contained cocaine/BE, as compared with only 4.3% of the urine samples. Most hair samples contained cocaine/BE In the range of 25–100 ng/sample (100 mg hair). All hair samples testing negative for cocaine/BE by RIA also tested negative by GCIMS, and four samples containing the highest amounts of cocaine and BE by RIA were similarly found to contain the highest amounts by GC/MS. Hair analysis, therefore, gives a wider window of detection of drug use than does urinalysis and shows merit in the confirmation of cocaine use in small clinical research studies.