Adverse effects of risperidone and haloperidol treatment in schizophrenia

Abstract

Purpose: Side effects of pharmacological treatment in schizophrenia continue to be a major issue in spite of the development of new antipsychotics. The aim of this study is to explore the adverse effects of conventional and atypical antipsychotic drugs and their associated factors. Methods: Over 3 months, 41 patients with schizophrenia were randomized to treatment with risperidone 1–12 mg ( n=21) or haloperidol 2–20 mg ( n=20) daily. Efficacy was assessed by improvement of psychotic symptoms, measured on the Positive and Negative Syndrome Scale (PANSS). The safety and tolerability were assessed with the Extrapyramidal Symptom Rating Scale, the UKU Side-Effect Rating Scale and clinical laboratory assessments. Results: Each treatment reduced psychotic symptoms. PANSS total scores, positive scores, and general psychopathology scores declined as trial went on without significant differences between the two groups. While PANSS negative scores improved better in the risperidone group than in the haloperidol group. The tolerability of antipsychotics was statistical significantly better in the risperidone than in the haloperidol-treated patients. The most frequent adverse effects for both groups were tremor and rigidity. Antipsychotics, their doses, and hyperprolactinemia predict short-term extrapyramidal side effects. Serum prolactin levels could predict parkinsonism and dyskinesia severity. However, dyskinesia was best predicted by the doses of neuroleptics. The predictive factor of dystonia was the antipsychotic drug itself. After adjusting drug doses and concomitant medications, side effects could be markedly improved. Conclusions: This study suggested that risperidone was superior to haloperidol in improving negative symptoms and better tolerated during the 12 weeks' treatment of schizophrenia. Serum prolactin levels could predict the severity of parkinsonism and dyskinesia.