Population pharmacokinetics of felbamate in children

Information about the pharmacokinetics of felbamate in children is limited. Even though it is claimed that monitoring of felbamate concentrations is unnecessary, many neurologists have requested therapeutic drug monitoring (TDM) for various reasons. This study used the NONMEM program to describe the pharmacokinetics and the influence of other anticonvulsants on the pharmacokinetics of felbamate. Felbamate, carbamazepine (CBZ), phenytoin (PHY), valproate (VPA), and barbiturate serum levels were obtained by our TDM service as requested by the clinician. The clearance and volume of distribution of felbamate were 41.1 ml/h/kg and 908 ml/kg, respectively. CBZ and PHY increased the clearance 49 and 40% while VPA decreased it 21%. Barbiturate had no significant effect. Clearance also decreased with age.