[Risperidone in the treatment of chronic schizophrenia: multicenter study comparative to haloperidol]

This study was designed to compare the efficacy and safety of five different doses of risperidone with a fixed dose of haloperidol in patients with chronic schizophrenia.

After a 1-week single-blind, placebo washout phase, 99 chronic schizophrenic patients were randomly assigned to double-blind treatment with 1, 4, 8, 12 or 16 mg risperidone or 10 mg haloperidol daily for 8 weeks. Efficacy was assessed throughout the study by the Positive and Negative Syndrome Scale (PANSS) for schizophrenia, and Clinical Global Impression (CGI). Safety assessments included the Extrapyramidal Symptom Ratinf Scale (ESRS) UKU Side Effect Rating Scale, vital signs, body weight, ECG and laboratory screening.

Risperidone had a bell-shaped dose-response curve, with optimal therapeutic responses occurring at a daily dose of 8 mg. The therapeutic response to haloperidol was similar to that seen with risperidone 16 mg. Risperidone was associated with significantly less extrapyramidal symptoms than haloperidol, as assessed by the ESRS. The effect was mirrored by the requirement for antiparkinson rescue medication. Furthermore, the overall incidence of adverse events was markedly lower with the optimum dose of risperidone than with haloperidol.

Risperidone is at least as effective as haloperidol for the treatment of chronic schizophrenia. Moreover, risperidone is associated with an improved adverse event profile and significantly less extrapyramidal symptoms which will have beneficial implications on patient quality of life and compliance. These results are in agreement with the results from the international multicenter trial.