Cyclic ureides |
Phenytoin | Blocks voltage-gated Na+ channels | Generalized tonic-clonic and partial seizures | Variable absorption, dose-dependent elimination; protein binding; many drug interactions | Ataxia, diplopia, gingival hyperplasia, hirsutism, neuropathy |
Phenobarbital | Enhances GABAA receptor responses | Same as above | Long half-life, inducer of P450 • many interactions | Sedation, ataxia |
Ethosuximide | Decreases Ca2+ currents (T-type) | Absence seizures | Long half-life | GI distress, dizziness, headache |
Tricyclics |
Carbamazepine | Blocks voltage-gated Na+ channels and decreases glutamate release | Generalized tonic-clonic and partial seizures | Well absorbed, active metabolite • many drug interactions | Ataxia, diplopia, headache, nausea |
Benzodiazepines |
Diazepam | Enhance GABAA receptor responses | Status epilepticus | See Chapter 22 | Sedation |
Clonazepam | | Absence and myoclonic seizures, infantile spasms | See Chapter 22 | Similar to above |
GABA derivatives |
Gabapentin | Blocks Ca2+ channels | Generalized tonic-clonic and partial seizures | Variable bioavailability • renal elimination | Ataxia, dizziness, somnolence |
Pregabalin | Same as above | Partial seizures | Renal elimination | Same as above |
Vigabatrin | Inhibits GABA transaminase | Partial seizures | Renal elimination | Drowsiness, dizziness, psychosis, ocular effects |
Miscellaneous |
Valproate | Blocks high-frequency firing | Generalized tonic-clonic, partial, and myoclonic seizures | Extensive protein binding and metabolism; many drug interactions | Nausea, alopecia, weight gain, teratogenic |
Lamotrigine | Blocks Na+ and Ca2+ channels, decreases neuronal glutamate release | Generalized tonic-clonic, partial, myoclonic, and absence seizures | Not protein-bound, extensive metabolism • many drug interactions | Dizziness, diplopia, headache, rash |
Levetiracetam | Binds synaptic protein, modifies GABA and glutamate release | Generalized tonic-clonic and partial seizures | Well absorbed, extensive metabolism • some drug interactions | Dizziness, nervousness, depression, seizures |
Tiagabine | Blocks GABA reuptake | Partial seizures | Extensive protein binding and metabolism • some drug interactions | Dizziness, nervousness, depression, seizures |
Topiramate | May block Na+ and Ca2+ channels; also increases GABA effects | Generalized tonic-clonic, absence, and partial seizures, migraine | Both hepatic and renal clearance | Sleepiness, cognitive slowing, confusion, paresthesias |
Zonisamide | Blocks Na+ channels | Generalized tonic-clonic, partial, and myoclonic seizures | Both hepatic and renal clearance | Sleepiness, cognitive slowing, poor concentration, paresthesias |