Risperidone may induce mania

Risperidone, a novel antipsychotic agent, is a benzis-oxol derivative that has potent serotonin (5-HT2) and dopamine (D-2) receptor antagonism. It has been reported to be an effective antipsychotic agent for positive symptoms of schizophrenia and to have a relatively low extrapyramidal symptom profile (Claus et al. 1992; Livingston 1994). Risperidone can be effective in acute mania, particularly when used in combination with mood stabilizers (Frazier 1999) but also when used alone (Goodnick 1995). In addition, patients with treatment-refractory bipolar disorder, including those with rapid cycling, have been reported to respond to risperidone (Vieta et al. 1998). On the other hand, cases of (hypo)mania associated with risperidone treatment have also been reported (Aubry et al. 2000; Zolezzi and Badr 1999). We here report two schizophrenic patients who developed manic symptoms at low to moderate doses of risperidone