Effects of aggregation on methamphetamine toxicity in mice.

Methamphetamine (MA) toxicity in aggregated mice was studied by varying the number of mice and the proportion of MA treated mice kept in the same confined space. The lethality was measured 24 h after intraperitoneal injections of MA at doses ranging from 10 to 100 mg/kg. MA lethality, over a wide dose range (15 to 50 mg/kg), was higher in aggregated mice than in those maintained in isolation. The greater the proportion of MA-treated mice in aggregation was, the higher the MA lethality was. In aggregations of 10 mice, MA was lethal at lower doses than in aggregations of 5 mice. These results indicate that the lethality of MA is influenced by confinement and aggregation.