Low concentrations of methamphetamine detectable in urine in the presence of high concentrations of amphetamine.

Twenty-two urine specimens reported by military drug-testing laboratories for the presence of high concentrations of amphetamine only were subject to further analysis for the presence of methamphetamine. The 22 urine specimens had concentrations of amphetamine in the range of 28,028 to 241,142 ng/mL. The specimens were also assayed for the respective isomeric ratio of d (S) and l (R) amphetamine and methamphetamine. The results suggest that urine specimens containing high concentrations of amphetamine in which the urine concentration ratio of methamphetamine to amphetamine is less than 0.5% with similar isomeric distribution of d-(S) and l-(R) amphetamine and methamphetamine, respectively, may not necessarily indicate polydrug use.