Response of the Emit II amphetamine/methamphetamine assay to specimens collected following use of Vicks inhalers.

The possible cross-reactivity of l-methamphetamine (desoxyephedrine) to the Syva Emit II amphetamine/methamphetamine assay was evaluated in urine specimens collected from seven subjects using Vicks Inhalers. The subjects were six males and one female ranging from 24 to 47 years of age. Four subjects used the inhaler every two waking hours for five consecutive days, while three subjects inhaled hourly for three consecutive days. All urine voids were collected, totaling 150 specimens. All specimens were analyzed by the Emit II assay on a Hitachi 717 automatic analyzer with a 1000-ng/mL d-methamphetamine cutoff calibrator. None of the inhaler specimens produced an Emit II response equal to or greater than the cutoff calibrator; all were negative. Specimens producing the highest rates were further analyzed by chiral GC/MS. The highest concentrations of l-methamphetamine were observed in urines from two subjects inhaling hourly: 1390, 1290, and 740 ng/mL. These specimens were collected the evenings of the second and third day. When used as directed or even with double the daily dose, Vicks Inhalers did not cause false-positive results in urine tested with the Emit II Amphetamine/Methamphetamine assay.