Sweat testing for cocaine, codeine and metabolites by gas chromatography -mass spectrometry

Sweat testing for drugs of abuse provides a convenient and considerably les s invasive method for monitoring drug exposure than blood or urine. Numerou s devices have been developed for collection of sweat specimens. The most c ommon device in current use is the PharmChek(TM) Sweat Patch, which usually is worn by an individual for five to ten days. This device has been utiliz ed in several field trials comparing sweat test results to conventional uri nalysis and the results have been favorable. Two new Fast Patch devices hav e been developed and tested that allow rapid collection of sweat specimens. The Hand-held Fast Patch was applied to the palm of the hand and the Torso Fast Patch was applied to the abdomen or the sides of the trunk (flanks) o f volunteer subjects participating in a research study. Both patches employ ed heat-induced sweat stimulation and a larger cellulose pad for increased drug collection. Sweat specimens were collected for 30 min at various times following administration of cocaine or codeine in controlled dosing studie s. After patch removal, the cellulose pad was extracted with sodium acetate buffer, followed by solid-phase extraction. Extracts were derivatized and analyzed by gas chromatography mass spectrometry (GC-MS) simultaneously for cocaine, codeine and metabolites. Cocaine and codeine were the primary ana lytes detected in sweat. Peak cocaine and codeine concentrations ranged fro m 33 to 3579 ng/patch and 11 to 1123 ng/patch, respectively, across all dos es for the Hand-held Patch compared to 22-1463 ng/patch and 12-360 ng/patch , respectively, for the Torso Fast Patch. Peak concentrations generally occ urred 4.5-24 h after dosing. Both drugs could be detected for at least 48 h after dosing. Considerably smaller concentrations of metabolites of cocain e and codeine were also present in some patches. Generally, concentrations of cocaine and codeine were higher in sweat specimens collected with the Ha nd-held Fast Patch than for the Torso Fast Patch. Drug concentrations were also considerably higher than those reported for the PharmChek(TM) Sweat Pa tch. The predominance of cocaine and codeine in sweat over metabolites is c onsistent with earlier studies of cocaine and codeine secretion in sweat. M ultiple mechanisms appear to be operative in determining the amount of drug and metabolite secreted in sweat including passive diffusion from blood in to sweat glands and outward transdermal migration of the drug. Additional i mportant factors are the physico-chemical properties of the drug analyte, s pecific characteristics of the sweat collection device, site of sweat colle ction and, in this study, the application of heat to increase the amount of drug secreted. Published by Elsevier Science B.V.