Efficacy and adverse effects of clozapine in the treatment of schizophrenia and tardive dyskinesia--a retrospective study of 387 patients.

Medical charts of 387 in-patients (schizophrenia n = 284, tardive dyskinesia, TD, n = 48), were analyzed to evaluate efficacy and adverse effects of clozapine. These patients were previously treated with between two and four other neuroleptics and were either therapy resistant or had severe side effects. Schizophrenic patients were treated with clozapine for 48 +/- 35 (TD 49 +/- 40) days, dosage was 189 +/- 119 (TD 220 +/- 176) mg. Four per cent showed worsening, 13% no change, 38% slight improvement, 42% marked improvement and 3% nearly total reduction of symptoms. In TD, 44% showed marked improvement, but only in 17% the drug was superior to previous neuroleptics. Adverse effects occurred in 56% of patients. Most frequent were sedation (17%), EEG alterations (16%), increase of liver enzymes (8%), hypotension (7%), hypersalivation (5%), fever (5%), ECG alterations (4%), tachycardia (3%), gastro-intestinal (3%) and delirious states (2%). A gradual increase in dosage seems to considerably reduce the incidence of some side effects. Clozapine treatment had to be discontinued because of severe side effects in 5.9%. In none of these patients did serious complications such as agranulocytosis occur. Only EEG alterations were significantly related to clozapine dosage (P less than 0.0005). At dismissal, most patients continued to receive clozapine; only in 22% (TD 20%) was it replaced by another neuroleptic. Thus, the ratio benefit/risk of clozapine treatment seems to be satisfactory in most of the negatively selected patients. Nevertheless, a gradual increase in dosage and careful control of hematological and other variables is highly recommended.