[Recent progress in development of psychotropic drugs (2)--antipsychotics]

The discovery of chlorpromazine led to rapid progress in drug therapy for schizophrenia. However, conventional neuroleptics frequently induce EPS and tardive dyskinesia in addition to the drawback of having little effect against negative symptoms. New types of atypical antipsychotics has been actively developed in Japan to overcome these drawbacks. Firstly, serotonin-dopamine antagonist (SDA) is most actively developed. Eight SDAs have been introduced into clinical trials: risperidone's trials have been finished and a NDA has been filed, Org 5222 has been dropped because of worsening of significant cases, and 6 SDAs (SM-9018, sertindole, seroquel, AD-5423, ziprasidone and olanzapine) are now under development. Secondly, OPC-14597, a unique atypical antipsychotic has been advanced to the phase 3 study, which has both DA autoreceptor-agonistic and D2-receptor blocking actions. Thirdly, we have much interest in NE-100, a selective sigma receptor antagonist which potently suppresses the phencyclidine-induced behaviors. Finally. a 5-HT3 receptor antagonist, alosetron was already dropped because it showed no antipsychotic effects, although it was introduced with great expectations. We hope that as many as possible new antipsychotics will be approved for the battle against schizophrenia.