Haloperidol plasma level after a test dose as predictor for the clinical response to treatment in acute schizophrenic patients.

Abstract

In a fixed-dose, double-blind study, the clinical response of schizophrenic patients to a high (0.40 mg/kg) or a low (0.15 mg/kg) dose of haloperidol (HL) was compared. The relationship between HL steady-state plasma levels and clinical improvement was examined. The utility of HL plasma level after a single test dose (0.05 mg/kg) in predicting the clinical response to treatment was evaluated. No difference in clinical improvement was observed between the two groups as a whole, although the high-dose group had a faster initial improvement. The high-dose group showed more extrapyramidal effects during treatment. No relationship was found between HL steady-state levels and clinical improvement. For the low-dose group, HL plasma level after the test dose was significantly positively correlated with the improvement after eight days of treatment. The test dose HL plasma level was no predictor of the clinical response to treatment in the high-dose group. The possibility of predicting the clinical response of schizophrenic patients to treatment from the plasma level after a test dose is still an open question that requires further studies.