Excretion of methamphetamine and amphetamine in human sweat following controlled oral methamphetamine administration

BACKGROUND: Understanding methamphetamine (MAMP) and amphetamine (AMP) excretion in sweat is important for interpreting sweat and hair testing results in judicial, workplace, and drug treatment settings. METHODS: Participants (n = 8) received 4 10-mg (low) oral doses of sustained-release S-(+)-MAMP HCl (d-MAMP HCl) within 1 week in a double-blind, institutional review board-approved study. Five participants also received 4 20-mg (high) doses 3 weeks later. PharmChek sweat patches (n = 682) were worn for periods of 2 h to 1 week during and up to 3 weeks after dosing. The mass of MAMP and AMP in each patch was measured by GC-MS, with a limit of quantification of 2.5 ng/patch. RESULTS: MAMP was measurable in sweat within 2 h of dosing. After low and high doses, 92.9% and 62.5% of weekly sweat patches were positive, with a median (range) MAMP of 63.0 (16.8-175) and 307 (199-607) ng MAMP/patch, respectively; AMP values were 15.5 (6.5-40.5) and 53.8 (34.0-83.4) ng AMP/patch. Patches applied 2 weeks after the drug administration week had no measurable MAMP following the low doses, and only 1 positive result following the high doses. Using criteria proposed by the Substance Abuse Mental Health Services Administration, 85.7% (low) and 62.5% (high) weekly sweat patches from the dosing week were positive for MAMP, and all patches applied after the dosing week were negative. CONCLUSIONS: These data characterize the excretion of MAMP and AMP after controlled MAMP administration and provide a framework for interpretation of MAMP sweat test results in clinical and forensic settings.