Pharmacokinetics of selegiline, R-methamphetamine, R-amphetamine, and desmethylselegiline in oral fluid after a single oral administration of selegiline.

BACKGROUND: Chiral analysis is a crucial way to differentiate selegiline (SG) intake from drug abuse. Oral fluid (OF) has been successfully used as an alternative matrix for blood testing in several pharmacokinetic studies.

OBJECTIVE: The aim of this study is to describe the pharmacokinetics of SG and its main metabolites in OF after a single oral administration of SG which is meaningful for results interpretation in forensic analysis.

METHODS: Ten milligrams of SG were orally administered to 8 volunteers, and OF samples were collected for up to 96 hours by having participants spit into polypropylene tubes without stimulation. These samples were submitted to liquid-liquid extraction before analysis by liquid chromatography-tandem mass spectrometry operating in positive ion multiple-reaction monitoring mode.

RESULTS AND CONCLUSIONS: After oral administration, each analyte could be detected in OF specimens from all volunteers with an initial detection time of 0.50 hours. The Cmax values of SG, R-MA, R-AM and DM-SG were 50.93-992.67 ng/mL, 29.78-653.64 ng/mL, 8.22-150.15 ng/mL, and 4.34-16.25 ng/mL, respectively, at 0.5 hours, 1-11 hours, 1.5-11 hours, and 0.5-6 hours post dose. The times when the compounds were last determined in OF were 5-24 hours for SG, 52-96 hours for R-MA, 31-96 hours for R-AM, and 13-31 hours for DM-SG after oral administration. There is a period of time in OF in which only MA and AM are present without SG and DM-SG after a single dose of SG. The pharmacokinetic data could provide supplementary interpretation for OF tests in forensic science and drug treatment programs.