Methamphetamine and Amphetamine Isomer Concentrations in Human Urine Following Controlled Vicks VapoInhaler Administration

• Published in: Journal of analytical toxicology 2014-10, Vol.38 (8), p.524-527
• Main Authors: Smith, Michael L., Nichols, Daniel C., Underwood, Paula, Fuller, Zachary, Moser, Matthew A., Flegel, Ron, Gorelick, David A., Newmeyer, Matthew N., Concheiro, Marta, Huestis, Marilyn A.
• Format: Article
• Language: English
• Subjects: Administration, Inhalation; Adolescent; Adult; Aged; Amphetamine - urine; Creatinine - urine; Dose-Response Relationship, Drug; False Positive Reactions; Female; Gas Chromatography-Mass Spectrometry; Healthy Volunteers; Humans; Immunoassay - methods; Male; Methamphetamine - urine; Middle Aged; Sensitivity and Specificity; Specimen Handling; Stereoisomerism; Substance Abuse Detection - methods; Young Adult
• ISSN: 0146-4760; 1945-2403
• DOI: 10.1093/jat/bku077

Legitimate use of legal intranasal decongestants containing l-methamphetamine may complicate interpretation of urine drug tests positive for amphetamines. Our study hypotheses were that commonly used immunoassays would produce no false-positive results and a recently developed enantiomer-specific gas chromatography–mass spectrometry (GC–MS) procedure would find no d-amphetamine or d-methamphetamine in urine following controlled Vicks VapoInhaler administration at manufacturer's recommended doses. To evaluate these hypotheses, 22 healthy adults were each administered one dose (two inhalations in each nostril) of a Vicks VapoInhaler every 2 h for 10 h on Day 1 (six doses), followed by a single dose on Day 2. Every urine specimen was collected as an individual void for 32 h after the first dose and assayed for d- and l-amphetamines specific isomers with a GC–MS method with >99% purity of R-(−)-α-methoxy-α-(trifluoromethyl)phenylacetyl derivatives and 10 µg/L lower limits of quantification. No d-methamphetamine or d-amphetamine was detected in any urine specimen by GC–MS. The median l-methamphetamine maximum concentration was 62.8 µg/L (range: 11.0–1,440). Only two subjects had detectable l-amphetamine, with maximum concentrations coinciding with l-methamphetamine peak levels, and always ≤4% of the parent's maximum. Three commercial immunoassays for amphetamines EMIT® II Plus, KIMS® II and DRI® had sensitivities, specificities and efficiencies of 100, 97.8, 97.8; 100, 99.6, 99.6 and 100, 100, 100%, respectively. The immunoassays had high efficiencies, but our first hypothesis was not affirmed. The EMIT® II Plus assay produced 2.2% false-positive results, requiring an enantiomer-specific confirmation.