The authors investigated the clozapine plasma levels of 148 psychiatric
inpatients. Multiple regression analysis revealed a linear relationship
between dose of clozapine and plasma concentrations. The analysis showed a
significant influence of dose, sex, smoking, weight, and age on the plasma
concentrations of clozapine under clinical conditions. These results
remained significant when clozapine doses below 150 mg/day and above 500
mg/day were excluded from the analysis.