Table 3 Comparative pharmacokinetic parameters for new AEDs4

AEDProtein binding, %Elimination T½, hSite of eliminationClinical notes
AED = antiepileptic drug; VPA = valproic acid; MHD = monohydroxy derivative.
Gabapentin04–6Renal, 100%Displays dose dependent absorption
Lamotrigine5515–30Hepatic, 90%Clearance (via glucuronidation) increased by enzyme-inducing AEDs, reduced by VPA; metabolites inactive
Topiramate9–1715–23Renal, 40–70%Fraction hepatically metabolized; increased by enzyme-inducing AEDs; metabolites inactive
Levetiracetam06–8Renal, 66%; hydrolysisof acetamide group, 34%Metabolism is nonhepatic; metabolites inactive
Oxcarbazepine404–9Hepatic, 70%Based upon 10 hydroxy carbazepine (MHD), the major, active metabolite
Tiagabine964–7Hepatic, 98%Oxidative metabolism to inactive metabolites
Zonisamide40–6024–60Hepatic, 70%Clearance increased by enzyme-inducing AEDs