A combined analysis of double-blind studies with risperidone vs. placebo and other antipsychotic agents: factors associated with extrapyramidal symptoms

Combined data from double-blind risperidone studies were used to analyse the severity of extrapyramidal symptoms (EPS) associated with treatment in patients with chronic schizophrenia. Factors associated with maximum EPS severity were increasing risperidone dose (less than or equal to 8 mg/day was similar to placebo), lower baseline EPS scores, and longer duration of psychotic symptoms, particularly in older patients. EPS severity was significantly greater in patients receiving haloperidol or other antipsychotics than in those receiving risperidone (4 to 8 mg/day) or placebo. Antiparkinsonian medications were required by significantly fewer patients treated with risperidone (4 to 8 mg/day) than by patients treated with haloperidol or other antipsychotics. Combined efficacy data showed that 4 to 8 mg/day was also the most efficacious dose range; there was no increase in efficacy with doses over 4 mg/day. Based on these data and post-marketing experience, 4 mg/day is an appropriate initial target dose for most patients with schizophrenia. Higher doses may be appropriate for patients with chronic illness, and lower doses may be appropriate for patients with a first psychotic episode or for elderly patients.