The effect of risperidone on schedule-induced polydipsia.

The effects of risperidone on the acquisition of schedule-induced polydipsia in rats were investigated in a chronic dose regime followed by seven days of withdrawal. Risperidone dose-dependently suppressed water intake and number of panel pushes. Drinking efficiency and free water intake in home cages were unchanged. By comparing the effects of risperidone in the present paper with the effects of different-neuroleptics in the same procedure from an earlier study, it appears that the effect of risperidone is intermediary to that of the 'typical' and 'atypical' neuroleptics. It may be concluded that risperidone acts as an atypical neuroleptic compound; however, increasing the dose only two-fold will cause EPS.