Medication Summary
Anti-seizure medications indicated for use in focal seizures are the medical treatment of choice. Patients generally require many years of treatment, so consideration of side effects is important.
Although the effect of anti-seizure medications in pregnancy may be unfavorable, the risk of medication to the fetus must be weighed against the risk of maternal seizures to the fetus.
Because of the risk of level fluctuations, patients should not switch between brand and generic anticonvulsants, and if a generic is used, patients should receive the same generic formulation consistently.
Anticonvulsants
Class Summary
These agents prevent seizure recurrence and terminate clinical and electrical seizure activity.
Carbamazepine (Tegretol, Tegretol XR, Carbatrol, Equetro, Epitol)
This is a first-line agent for partial seizures with or without secondary generalization. Carbamazepine is particularly effective in the treatment of nocturnal motor/dystonic frontal lobe seizures. However, it carries a potential for hematologic and other adverse effects; blood monitoring is recommended. Carbamazepine is available in the form of tablets, extended release tablets, extended release capsules, and a suspension. Patients who are not using the extended release form often require dosing 3 times a day.
Phenytoin (Dilantin, Dilantin Infatabs, Phenytek)
Phenytoin is available as tablets, capsules, Infatabs, and suspension. It is a first-line agent for partial seizures. The advantages of phenytoin include an ability to quickly achieve a therapeutic level and the possibility of once-daily dosing (Dilantin Kapseals), which increases compliance.
Valproic acid (Depacon, Depakene)
This is available in the form of tablets, capsules, solution, and sprinkles and is also available in injectable form. Although it is considered a first-line agent for the treatment of primary generalized epilepsy, the drug is indicated for partial seizures as well, particularly for patients with secondary generalization. It must be used cautiously in women of childbearing age. The drug has limited use in young children because of a risk of potentially fatal hepatic failure.
Gabapentin (Neurontin, Gralise, Neuraptine)
Gabapentin is indicated for use in partial seizures with or without secondary generalization. It has relatively few drug interactions and adverse effects.
Lamotrigine (Lamictal, Lamictal ODT, Lamictal XR)
Lamotrigine is a newer agent; it is effective for partial seizures with or without secondary generalization. The drug's main side effect of concern is rash, which may be severe.
Levetiracetam (Keppra, Roweepra, Spritam)
This is a newer agent; it is effective for partial seizures with or without secondary generalization. Levetiracetam has few adverse effects and no drug-drug interactions. It does not require blood monitoring, although slight decreases in red blood cell (RBC) and white blood cell (WBC) counts have been reported.
Oxcarbazepine (Trileptal, Oxtellar XR)
Oxcarbazepine is indicated as monotherapy or adjunctive therapy in the treatment of partial seizures with or without secondary generalization. Its mechanism of action is similar to that of carbamazepine, without metabolism to epoxide. The active metabolite is MHD (monohydroxy derivative).
If a patient is being converted from carbamazepine to oxcarbazepine, the inducing effect of carbamazepine on cytochrome P-450 enzymes will be reduced, and other antiepilepsy drugs (AEDs) may need adjustment. There is no IV form available. If added to phenytoin, oxcarbazepine may elevate phenytoin levels by as much as 20%.
Topiramate (Topamax, Quedexy XR, Trokendi XR)
Topiramate is indicated for the adjunctive treatment of partial seizures with or without secondary generalization, and for tonic-clonic seizures. It is approved for adults and for children aged 2-16 years. Topiramate has multiple mechanisms of action.
Zonisamide (Zonegran)
This drug is indicated for adjunctive treatment of partial seizures with or without secondary generalization. Evidence exists that zonisamide is effective in myoclonic and other generalized seizure types as well.
Tiagabine (Gabitril)
Tiagabine is indicated for adjunctive treatment of partial seizures with or without secondary generalization. The mechanism of antiseizure action unknown but is believed to be related to an ability to enhance the activity of gamma-aminobutyric acid (GABA), a major inhibitory neurotransmitter in the central nervous system (CNS).
Pregabalin (Lyrica, Lyrica CR)
Pregabalin is a structural derivative of GABA; its mechanism of action unknown. It binds with high affinity to the alpha2-delta site (a calcium channel subunit). In vitro, it reduces the calcium-dependent release of several neurotransmitters, possibly by modulating calcium-channel function. The US Food and Drug Administration (FDA) approved pregabalin for neuropathic pain associated with diabetic peripheral neuropathy or postherpetic neuralgia and as an adjunctive therapy in partial-onset seizures.
Ethotoin (Peganone)
Ethotoin may act in the motor cortex where it may inhibit the spread of seizure activity. The activity of the brain stem centers responsible for the tonic phase of grand mal seizures may also be inhibited.
Lacosamide (Vimpat)
Lacosamide selectively enhances slow inactivation of voltage-gated sodium channels, resulting in stabilization of hyperexcitable neuronal membranes and inhibition of repetitive neuronal firing. It is indicated for adjunctive therapy for partial-onset seizures.
Vigabatrin (Sabril)
Vigabatrin is an irreversible inhibitor of GABA transaminase, thereby increasing the level of the inhibitory neurotransmitter GABA.
Divalproex sodium (Depakote, Depakote ER, Depakote Sprinkles)
Considered the drug of first choice for primary generalized epilepsy, valproate has a very wide spectrum and is effective in most seizure types, including myoclonic seizures. It has multiple mechanisms of anticonvulsant effects, including increasing gamma-aminobutyric acid (GABA) levels in brain as well as T-type calcium channel activity. The extended-release (ER) formulation allows for once-a-day administration.
