PharmChem, Inc is the manufacturer and sole provider of the PharmChek® Drugs of Abuse Sweat Patch. a long-term and continuous drug testing device that cannot be easily adulterated, tampered, or substituted. The PharmChek® Sweat Patch is worn on the body for 10+ days where all evidence of drug use during the wear-period is captured in the cellulose pad and submitted to the laboratory for analysis.