Decrease axonal conduction by preventing Na+ influx (MOA)

Increase inhibitory tone by facilitation of GABA-mediated hyperpolarization (MOA)

Decrease excitatory effects of glutamic acid (MOA)

Lamotrigine & topiramate (block AMPA receptors)

Felbamate (block NMDA receptors)

Decrease presynaptic Ca2+ influx through T-type channels in thalamic neurons (MOA)

Partial seizure (simple or complex)

DOC

General seizure (tonic clonic)

DOC

General seizure (absence)

DOC

Status epilepticus

Phenytoin

MOA: blocks axonal Na+ channel in inactive state (blocks seizure propagation)

Cytochrome P450 inducer

Zero -order kinetics

SE: gingival hyperplasia, hirsutism, osteomalacia, megaloblastic anemia (folate), cleft lip/palate

Carbamazepine

MOA: axonal block of Na+ channels (inactive state)

DOC: trigeminal neuralgia (tic doleoreaux)

CYP450 inducer

SE: Megaloblastic anemia, aplastic anemia, increase ADH secretion, cleft lip/palate spina bifida

Valproic Acid

MOA: Blocks Na+ channels, inhibits GABA transaminase, blocks T-type Ca2+ channels

Uses: seizure, bipolar mania, migraines

SE: Hepatotoxicity (from metabolite), thrombocytopenia, pancreatitis, alopecia, spina bifida

Ethosuximide

MOA: blockade of T-type Ca2+ channels and thalamic neurons

DOC: absence seizures

General features of anticonvulsants

Additive w/ other CNS depressants

Avoid abrupt w/drawl

B/c CYP450 inducers --> dec efficacy of OCP's (esp. phenytoin, carbamazepine, phenobarb.)

Felbamate & Lamotrigine

Adjunct therapy in seizure states

MOA: block Na+ channels and glutamate receptors

SE: hepatotoxicity

Aplastic anemia (felbamate)

Steven's johnson syndrome (lamotrigine)

Gabapentin

MOA: increases GABA effects

Uses: seizure states, neuropathic pain (postherpetic neuralgia)