Comparative study between active and passive exposure of methamphetamine vapor in mice

Urinary profiles of methoxyphenamine and its metabolite after inhalation of methoxyphenamine smoke in humans: aiming to distinguish between active and passive exposure

“…When METH is actively inhaled, the urinary excretion rate up to 72 h is reported to be approximately 37% [12], which is comparable to the urinary excretion rate when METH was administered orally [16]. The urinary excretion rate of MPA in mice during 24 h after active inhalation was about 20% [22], which is comparable to the urinary excretion rate when MPA was administered orally to humans [42,43]. These reports suggest that the urinary excretion rates of the unchanged form after inhalation of MPA and METH are comparable.…”

“…If inhalation of MPA caused toxicity, effects on the CNS would be observed. In our previous study, a temporary and slight decrease in body temperature and locomotor activity were observed in mice exposed to MPA smoke, suggesting that its inhalation may have a mild depressive effect on the CNS [22]. Salbutamol, a β2-receptor agonist similar to MPA, has been reported to inhibit locomotor activity at high doses in rats and mice [35,36].…”

“…Salbutamol, a β2-receptor agonist similar to MPA, has been reported to inhibit locomotor activity at high doses in rats and mice [35,36]. While measuring locomotor activity in the open field is a good method for evaluating CNS stimulants such as METH [22,37], it is not suitable for evaluating CNS depressants because mice acclimated to the environment are inactive and their body temperature tends to decrease [38]. Therefore, in this study, locomotor activity was measured using the running wheel, which is thought to be a superior method for evaluating depression of the CNS [30].…”

“…Intervals containing samples with urinary drug concentrations below the limit of quantitation are indicated by white marks. When the urinary concentrations of MPA and ODMP of the sample were above the limit of detection and below the limit of quantitation, 0.5 and 0.25 ng/mL were applied, respectively, and when below the limit of detection, 0 ng/mL was applied for calculations total urinary excretion rate of METH and AMP was similar to that of MPA and ODMP after mice were exposed to smoke generated by heating METH or MPA, and the urinary excretion patterns were also similar [22]. Therefore, in this study, urinary concentrations of MPA and ODMP were measured after inhalation of MPA to estimate the changes in urinary concentrations of METH after its inhalation.…”

“…Clinical studies using METH are not legally and ethically allowed in Japan. Therefore, we investigated the possibility of using methoxyphenamine (MPA), which is a non-regulated and structural analog of METH, as a model drug for METH in mice [22]. We found that mice exposed to METH or MPA smoke exhibited similar patterns of urinary excretion of the unchanged form.…”