Phenytoin potentiates methamphetamine-induced behavior in mice

We demonstrated that stereotyped behavior and tremor induced by methamphetamine (MA) were potentiated by pretreatment with phenytoin (PNT) in mice. Similar enhancing effects were obtained by pretreatment with carbamazepine. Gas chromatographic study demonstrated that pretreatment with PNT increased MA concentrations in the brain to approximately 2.5 times of control level. The increased MA concentrations were thought to be a major factor for the observed potentiation of MA-induced behavior by PNT. However, all MA-induced behavior were not equally potentiated; tremor was enhanced more than stereotypy. These results suggest that central neuronal mechanisms may also be involved in PNT-potentiated MA-induced behavior in mice.