Anti Epileptic Drugs Table

Drug

Target Receptor

Mechanism of Action

Phenytoin

Inhibits Na+ channels

Modifies neuronal excitability; for Partial seizures

Many drug and OC interactions, induces hepatic enzymes

Adverse: gingival hyperplasia, hirsutism, interfere w/ thyroid tests

Carbamazepine

Inhibits Na+ channels

Decreases synaptic transmission; Partial seizures

Many drug and OC interactions, induces own hepatic enzymes

Adverse: epoxide int., liver damage, leukopenia, LFTs required

Oxcarbazepine

Inhibits Na+ & Ca++ channels

Enhances K+ currents

Metabolite is active form

Adverse: hyponatremia, less hepatic enzyme induction

Phenobarbitol

(barbiturate)

GABAa, inhibits Ca channels

Enhance inhibition, GABA binding, Partial and Tonic-clonic

Adverse: accumulation, addiction, cross tolerance, induces CYP450, drug and OC interactions

Primidone

(barbiturate)

Inhibits Na+ channels

Metabolized to phenobarbitol and PEMA; Partial and Tonic-clonic

Adverse: sedation/intoxication immediately after administration, induces CYP450, drug and OC interactions

Gabapentin

Unknown

Amino acid analog of GABA; wide usage, no interactions

Partial seizure adjunct therapy

Tiagabine

GABA (GAT-1) uptake inhibitor

availability of GABA, inhibition

Partial seizure adjunct therapy

Zonisamide

Inhibits Na & Ca (T type) channels

Sulfonamide derivative, Partial seizure adjunct therapy

Adverse: allergies, renal calculi, teratogen, few interactions

Levetiracetam

Inhibits K+ rectifier channel, inhibits Ca (N type) channel

Inhibits negative modulation of GABAa by Zn++ and b-carboline, no interactions discovered yet, Partial seizure adjunct therapy

Felbamate

Inhibits NMDA receptors

GABA transmission, glutamate excitation, Refractory cases

Adverse: affects CYP450 to lesser degree, aplastic anemia, liver failure, LFTs required

Vigabatrin

Inhibits GABA transaminase degradation enzyme

Not approved in US. GABA availability, Refractory cases

Adverse: irreversible visual field deficits

Ethosuximide

Inhibits Ca (T type) channels

Absense seizures, few interactions

Adverse: skin reactions, blood dyscrasias

Valproic acid/ Sodium Valproate

Inhibits Na & Ca (T type) channels & GABA-T

GABA synthesis, membrane hyperpolarization, Broad Spectrum

Adverse: hepatotoxicity in children, pancreatitis, LFTs required, inhibits CYP450

Lamotrigine

Inhibits Na+ channels, inhibits glutamate release

For Lennox-Gastaut syndrome in children, Broad Spectrum

Adverse: Stevens-Johnson syn, few drug and OC interactions

Topiramate

Inhibits Na channels, AMPA/KA antagonist

GABA transmission, glutamate excitability, Broad Spectrum

Adverse: myopia, oligohydrosis, metabolic acidosis, weight loss, affects CYP450 to lesser degree