SOFT - TIAFT 1998 Scientific Session 3 Thursday October 8, 1998
Click Picture Rebecca A. Jufer1, Sharon L. Walsh2 and Edward J. Cone1

1Addiction Research Center, DIR, NIDA and 2Dept. of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, MD, USA

Chronic drug administration can result in accumulation and longer elimination times upon cessation of use. It has been suggested that cocaine metabolites can be detected in urine for several weeks following long-term, high-dose administration (Weiss and Gawin, 1988). We are currently conducting a clinical study of chronic oral cocaine administration. Cocaine abusing volunteers were administered oral cocaine in up to 16 sessions. The study was conducted on a closed clinical ward. In each session, volunteers received 5 equal doses of oral cocaine with 1 hour between doses. Across sessions, cocaine was administered in ascending doses with an initial dose of 100 mg (500 mg/day) up to 400 mg (2g/day), increasing by 25mg/dose/session (125 mg/session). Participation in the study was terminated if cardiovascular safety parameters were exceeded. For the 11 volunteers included in this report, the final completed daily doses ranged from 750 mg to 2000 mg. Urine specimens were collected throughout the study and collection continued during the withdrawal phase (range 4.85-12.82 days). Specimens were analyzed with the EMIT® d.a.u.™ Cocaine Metabolite Assay. Three cutoff concentrations of 300, 150 and 75 ng/mL were employed. The mean (N=11) urinary detection times (days±SEM) at each cutoff concentration were as follows:
Mean Detection Times (range)
Cutoff Concentration (ng/mL)

Last Consecutive Positive Last Positive
300 150 75 (N=9) 300 150 75 (N=9)
3.1±0.1 4.2±0.1 5.2±0.2 4.1±0.1 5.1±0.1 6.4±0.1
(1.3-5.0) (2.3-5.9) (3.7-7.2) (3.0-5.1) (3.2-6.7) (4.2-8.1)

Four subjects continued to test positive for cocaine metabolite at the time of their discharge (one at 300 ng/mL; three at 75 ng/mL). All other subjects produced at least one negative urine specimen before discharge. These detection times are longer than the typically reported detection time of approximately 2-3 days following acute dosing, but are consistent with the elimination half-life for benzoylecgonine, approximately 7.5 hours. Overall, these data indicate that chronic cocaine administration results in urine detection times of 3-5 days at the 300 ng/mL DHHS cutoff concentration. However, the use of lower cutoff concentrations would provide detection times of 3-7 days.

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