Sulpiride and Haloperidol in Schizophrenia: A Double-blind Cross-over Study of Therapeutic Effect, Side Effects and Plasma Concentrations

In a double-blind cross-over trial, 20 chronic schizophrenic patients were treated with sulpiride and haloperidol in two 12-week periods. The final median dose of sulpiride was 2000 mg/day (range 800–3200) and of haloperidol 12 mg/day (range 6–24). Sulpiride had an antipsychotic effect and therapeutic profile not significantly different from that of haloperidol. In spite of the high doses of sulpiride, extrapyramidal side-effects were seen less frequently during the first four weeks of the sulpiride period than during the corresponding haloperidol period (P < 0.05), whereas autonomic side-effects were equally rare for both drugs. A positive correlation was found between daily dose and plasma concentration of both sulpiride (P < 0.001) and haloperidol (P < 0.05), but no correlation could be established between clinical effects and plasma levels of either neuroleptic.