Newer Atypical Antipsychotic Drugs

Kim, Chang Yoon

Abstract

During the last decade, new era of antipychotic drugs has begun with the introduction of risperidone and olanzapine following clozapine. These atypical drugs are characterized by fewer extrapyramidal side effects and at least equal or superior clinical efficacy, although their effects on negative symptoms and refractory cases remain controversial. For these reasons, these atypical antipsychotic drugs are now recommended as a choice of first line treatments for schizophrenia and these new atypical drugs are replacing conventional antipsychotic drugs. These atypical drugs, however, are not same in terms of efficacy and side effects. Risperidone produces more frequent dose-dependent extrapyramidal symptoms and olanzapine causes significant weight gains more frequently compared to other atypical antipsychotic drugs. More recently, several newer atypical drugs are being released or will be available in the near future. Quetiapine and amisulpride are already being used in Europe and will be available soon in Korea. Quetiapine, even at high doses, has been reported to have placebo-level extrapyramidal side effects. It has been well tolerated in patients with parkinson's diseases who are particularly sensitive to extrapyramidal side effects. Amisulpride is known to have dual dopamine blockade effects. Ziprasidone, which had not been approved due to concerns about possible QTc prolongation, has been finally approved by FDA. Ziprasidone has been reported to cause little weight gain compared to other atypical drugs. Aripiprazole, data on which has been submitted to FDA for approval, has a unique mechanism of action as a dopamine partial agonist. Iloperidone is known to be under large-scale phase III clinical trial as a promising new antipsychotic drug. In this paper, these newer atypical antipsychotic drugs were reviewed with respect to efficacy and safety based on the data of clinical trials.