Clozapine in the treatment of schizophrenic patients: an international multicenter trial.

One hundred twenty schizophrenic patients were treated with clozapine for two months in accordance with a standard trial protocol at ten research centers in the USSR, Czechoslovakia, Hungary, Poland, Bulgaria, and in the GDR. The daily dose ranged from 50 mg to 550 mg (mean: 272.1 mg for responders; 298 mg for nonresponders). In 94 patients (78%) the disease was clearly progressive; in 57 (47.5%) it was continuous; in 63 (52.5%) it was episodic. Before the start of clozapine treatment, 95 of the patients (79%) had been receiving other neuroleptics. There was a positive therapeutic response in 80% of the responding patients. The effect of clozapine was closely related to the dominant syndrome structure of the psychosis: a positive response was noted in 89% of patients with delusional, hallucinatory-delusional, and catatonic states and in 60% of patients with affective-delusional syndromes. Moderate side effects were noted in 87 patients (73%). The incidence of side effects reached a peak during the first four weeks of treatment and then declined despite maintenance of or even an increase in the daily clozapine dose. Hematological changes (moderate leukocytosis and thrombocytopenia) were noted in eight patients (6.7%).