Estimation of number of days after last intake of methamphetamine in Japanese abusers: Amphetamine to methamphetamine ratios in urine of Japanese abuser

Abstract

The objective of this study is to estimate the number of days after the last intake of methamphetamine/HCl in Japanese abusers. Methamphetamine and its metabolite, amphetamine, in residual urine after screening with a drug test kit were analyzed by liquid chromatography-mass spectrometry (LC/MS). As would be expected for this pair of the parent drug and metabolite, there was a linear increase in the ratio (on a peak area basis) of amphetamine to methamphetamine with increasing number of days after the last intake. Although this study was conducted in a limited number of abusers, it was confirmed that the number of days since the last use of methamphetamine can be estimated to some extent by examining the ratio of amphetamine to methamphetamine in the urine of Japanese abusers.