Structural model
A novel rFIX-Fc population PK model using clinical data including children <12 years of age was developed (Table 2). A two-compartment model with a central and a peripheral compartment adequately described our data. Addition of a second peripheral compartment did not improve the fit of the model to the data. All PK parameters were allometrically scaled. With allometric scaling, body weight is included in the structural model. IIV could be estimated for CL, V1 and V2, with a correlation between CL and V1. The clinical data supported the estimation of IOV on CL.