[Plasma level monitoring of psychotropic drugs in children. I-Haloperidol (author's transl)].

Monitoring of haloperidol plasma levels during long-term treatment is not commonly practised in adults and even less in children. In this study, haloperidol plasma levels were measured in children and teenagers with psychotic episodes or abnormal movements. Steady state concentrations ranged from 0.7 to 19 ng/ml. They were apparently unrelated to the doses administered (15-285 micrograms/kg/day), and variations of up to 15-fold were observed with the same dosage. In contrast, a significant correlation (p less than 0.02) was determined between age and dose-concentration ratio. Side-effects also seemed to be significantly related to plasma levels (p less than 0.01); they occurred at concentration higher than 6 ng/ml. Therapeutic response was observed with plasma concentrations of 1 to 4 ng/ml in cases with abnormal movements, but no dose-effect relationship was found in patients with psychotic episodes.