Redisplay the previous page that appeared in this window.
Drug Treatment for Seizures
AgentMechanism of ActionDosageBenefitsSide EffectsNotes
CarbamazepineInhibits voltage gated Na+ channels (inhibits action potentials)600-1200 mg/dFamiliar, inexpensiveRare blood dyscrasias and hepatitis; diplopia, ataxia commonSlow release available for bid dosing.
Narrow therapeutic window*
EthosuximideInhibits T-type calcium channels250-500 mg/dSimple to use and dosed qd, bidRare blood dyscrasiasOnly effective for absence seizures*
FelbamateMixed1200-3600 mg/dEffective for wide variety of severe seizuresCommon aplastic anemia (1 in 40,000) and hepatitis (1 in 80,000)Common elevated valproic acid and phenytoin levels.
Reserved for intractable epilepsy because of risks*
GabapentinUnknown1800-3600 mg/dNo drug interactionsRare neurotoxicity; no end-organ toxicitiesMany pills per day, dosed tid at effective doses.
Not protein bound or metabolized*
LacosamideEnhancing slow inactivation of voltage gated sodium channels200-400 mg/dAvailable in both oral and iv formDizziness, headache, nausea, and diplopiaFDA approved for adjunct treatment for partial epilepsy October 2008*
LamotrigineUnknown100-600 mg/dEffective for partial and generalized seizuresCommon benign rash (1:50-1:500); Rare severe rash - Stevens Johnson (1:40,000)Rash is more likely with fast titration or with concomitant valproic acid.
Dose is higher with enzyme-inducing drugs and lower with valproic acid*
LevetiracetamUnknown1000-3000 mg/dFew drug interactionsUncommon neurotoxicity, no end-organ toxicitiesWell tolerated*
OxcarbazepineInhibits voltage gated Na+ channels (inhibits action potentials)900-2400 mg/dFewer side effects than carbamazepine; dosed bidHyponatremia uncommon; neurotoxicity uncommonNo significant induction of most liver enzymes*
PregabalinModulates calcium channels150-600 mg/dFew drug interactionsNeurotoxicity, weight gain, peripheral edema, and visual changes are uncommonFDA schedule V designation*
PhenobarbitalGamma-aminobutyric acid(A) agonist90-180 mg/dInexpensive, qd dosingSedation; hyperactivity in childrenExcellent drug if well tolerated
PhenytoinInhibits voltage gated Na+ channels (inhibits action potentials)200-300 mg/dFamiliarRare blood dyscrasias and hepatitis; common neurotoxicity, gum hyperplasia, hirsutism, osteoporosisNarrow therapeutic window*
RufinamideUnknown45 mg/kg·d or 3200 mg/dApproved for severe epilepsy like that associated with Lennox-Gastaut syndromeSomnolence or fatigue, coordination abnormalities, dizziness, gait disturbances, and ataxia. Contraindicated in patients with familial short QT syndromeFDA approved for adjunctive treatment of seizures associated with the Lennox-Gastaut syndrome in children 4 years and older, and adults*
TiagabineInhibits reuptake of GABA12-56 mg/dWell toleratedUncommon neurotoxicityShort half-life may require tid or qid dosing in some patients*
TopiramateMixed, carbonic anhydrase inhibitor200-400 mg/dEffective for partial seizures and Lennox-Gastaut syndromeRare nephrolithiasis; common cognitive side effects above 400 mg/dNot well tolerated above 400 mg/d in many patients*
Valproic acidAugments production and inhibits metabolism of GABA750-3000 mg/dEffective for all partial and generalized seizuresRare hepatitis (1:40,000); common tremor, weight gain, thrombocytopeniaHepatitis most common in children on multiple antiepileptic drugs, with mental retardation*
ZonisamideUnknown200-400 mg/dqd dosing is possible because of 60 hr half-lifeRare nephrolithiasis, heat intolerance; uncommon neurotoxicity, metabolic acidosisBetter tolerated bid.
The FDA issued an alert regarding the risk of metabolic acidosis in some patients using zonisamide*

bid = twice daily; FDA = Food and Drug Administration; GABA = γ-aminobutyric acid; qid = four times daily; qd = once daily; tid = three times daily.

* The FDA requires a warning label regarding the increased risk of suicidal thoughts and behaviors associated with the use of this drug. The American Epilepsy Society issued a position statement in response to this FDA requirement.