Pharmacokinetics of Antiepileptic Drugs
| Plasma Therapeutic Concentration (μg/mL) | Protein Binding (%) | Elimination Half-Time (h) | Route of Elimination | | Carbamazepine | 6-12 | 70-80 | 8-24 | Hepatic metabolism (active metabolite) | | Clonazepam | 0.02-0.08 | 80-90 | 30-40 | Hepatic metabolism | | Diazepam | | 95 | 20-35 | Hepatic metabolism (active metabolites) | | Ethosuximide | 40-100 | 0 | 20-60 | Hepatic metabolism (25% excreted unchanged) | | Felbamate | | 22-25 | 20-23 | Renal excretion | | Gabapentin | 2-20 | 0 | 6 | Renal excretion | | Lamotrigine | | 54 | 25 | Hepatic metabolism | | Lorazepam | | 80 | 14 | Hepatic metabolism | | Oxcarbazepine | | 40 | 8-10 | Renal excretion | | Phenobarbital | 10-40 | 48-54 | 72-144 | Hepatic metabolism (25% excreted unchanged) | | Phenytoin | 10-20 | 90-93 | 9-40 | Saturable hepatic metabolism | | Primidone | 5-12 | 20-30 | 4-12 | Hepatic metabolism to active metabolites of which 40% are excreted unchanged | | Tiagabine | | 95 | 5-8 | Hepatic metabolism | | Topiramate | | 10 | 8-15 | Renal excretion and hepatic metabolism | | Valproic acid | 50-100 | 88-92 | 7-17 | Hepatic metabolism (active metabolites) | | Zonisamide | | 50 | 50-70 | Hepatic metabolism |
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Adapted in part from Brodie MJ, Dichter MA. Antiepileptic drugs. N Engl J Med. 1996;334:168-175; Dichter MA, Brodie MJ. New antiepileptic drugs. N Engl J Med. 1996;334:1583-1590.