Susceptibility of PharmChek Drugs of Abuse Patch to Environment Contamination.

The PharmChek Drugs of Abuse Patch was evaluated for contamination by low microgram quantities of cocaine, methamphetamine, and heroin from outside the patch contamination from without, CFWO and inside the patch, on the exterior skin contamination from with, CWFI. To study CFWO, patches were first saturated with artificial sweat and attached to clean Petri dishes. Exposure of the outer membrane of the patch to drugs in mildly basic solutions showed increasing levels of drugs inside the patch over time. Drugs must be uncharged to pass through the exterior of the patch. Drugs applied in acidic, artificial sweat pH 4.7, where most drugs are positively charged, resulted in little or no CFWO in the patch. Sweat Patches exposed to drug vapors revealed virtually no CWFO when both the pad and the patch exterior were dry however, the patch contained significant drug concentrations when the pad was moistened with artificial sweat and the patch exterior membrane was moistened with either artificial sweat or tap water. In vivo experiments, testing CFWl, showed positive patch test results when drugs were placed externally on the skin before the patch was applied, despite normal hygenic washing, passage of time up to six days, and swabbing with 70 isopropanol