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

Abstract

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.

Figures

Fig. 1. Methamphetamine administration schedule for 4 10-mg (low) and 4 20-mg (high) oral MAMP doses

Washout refers to the 2 weeks before drug administration that permitted excretion of previously self-administered illicit drugs. P1, P2, and P3 refer to the 1st, 2nd, and 3rd weeks after the low and high doses to monitor residual drug excretion after the dosing week.

Fig. 2. Short-term sweat patch application and removal schedule

Short-term sweat patches were applied for 0–2, 2–4, 4–8, 8–23, and 23–24 h after the first low- and high-dose methamphetamine administration, and 0–9 and 9–24 h for the other 3 dosing days.