Monitoring drug use with a sweat patch: an experiment with cocaine

Eighteen male subjects participated in a clinical study to examine a skin patch method of monitoring drug use. On the first day of each of two periods, 14 Band-aid type collection devices (sweat patches) were applied to a subject's torso, biceps, and back. On the following day, the subject took 50 or 126 mg cocaine hydrochloride intranasally. A 1-week interval separated treatment periods, and the order of dose levels was counterbalanced. On the days subjects received cocaine, one patch was removed before treatment, and five were removed after treatment. Subjects then returned over the next 7 days for removal of the remaining patches. They provided urine samples immediately after each patch removal. A group of 18 nondrug users also wore patches for up to 12 days. Analysis of the patch content yielded cocaine levels from the cocaine subjects that accurately reflected usage. Mean levels for 16 subjects were significantly different for the two treatment doses. However, given the between-dose and between-subject variability, the data cannot be used to determine either dose or time of use. The data do indicate, however, that the patch technology can be used to diagnose a single episode of cocaine use as far back as 7 days.