Abstract
Methamphetamine is included in drug testing programmes due to its high abuse potential. d-Methamphetamine is a scheduled potent central nervous system stimulant, while l-methamphetamine is the unscheduled active ingredient in the over-the-counter nasal decongestant Vicks® VapoInhaler™. No data are available in oral fluid (OF) and few in plasma after controlled Vicks® VapoInhaler™ administration. We quantified methamphetamine and amphetamine enantiomers in OF collected with two different devices and plasma via a fully validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. Additionally, OF were analyzed with an on-site screening device. Sixteen participants received 7 Vicks® VapoInhaler™ doses according to manufacturer's recommendations. Specimens were collected before and up to 32 h after the first dose. No d-methamphetamine or d-amphetamine was detected in any sample. All participants had measurable OF l-methamphetamine with median maximum concentrations 14.8 and 16.1 μg/L in Quantisal™ and Oral-Eze® devices, respectively, after a median of 5 doses. One participant had measurable OF l-amphetamine with maximum concentrations 3.7 and 5.5 μg/L after 6 doses with the Quantisal™ and Oral-Eze® devices, respectively. There were no positive DrugTest® 5000 results. In the cutoff range 20-50 μg/L methamphetamine with amphetamine ≥limit of detection, 3.1-10.1% of specimens were positive; first positive results were observed after 1-4 doses. Two participants had detectable plasma l-methamphetamine, with maximum observed concentrations 6.3 and 10.0 μg/L after 2 and 5 doses, respectively. Positive OF and plasma methamphetamine results are possible after Vicks® VapoInhaler™ administration. Chiral confirmatory analyses are necessary to rule out VapoInhaler™ intake. Implementing a selective d-methamphetamine screening assay can help eliminate false-positive OF results.