Response of EMIT amphetamine immunoassays to urinary desoxyephedrine following Vicks inhaler use

The cross-reactivity of l-methamphetamine (l-desoxyephedrine) to the EMIT-d.a.u. class (EC) and EMIT-d.a.u. monoclonal amphetamine/methamphetamine (EM) assays was evaluated in urine specimens collected from six subjects using Vicks inhalers. The subjects were five men and a woman ranging from 27 to 47 years old. Four subjects used the inhaler as recommended by the manufacturer for five consecutive days; two subjects used double this dosage for three consecutive days. All urine voids were collected, totaling 132 specimens. All specimens were analyzed by the EC and EM assays. Specimens yielding a positive response were then analyzed by chiral and achiral gas chromatography/mass spectrometry (GC/MS). No specimen was positive by the EM assay, whereas 17 specimens yielded positive EC results. One subject for form the "as recommended" group had six positive specimens with maximum l-desoxyephedrine of 872 ng/ml. Both subjects using twice the recommended dosage had positive specimens, maximum l-desoxyephedrine of 1,560 ng/ml. No positive specimen contained > 200 ng/ml l-amphetamine.