THERAPEUTICS

Brands

• Dilantin, Phenytek, Epanutin, Fosphenytoin, Cerebyx

Generic?

• Yes

Class

• Antiepileptic drug (AED)

Commonly Prescribed for

(FDA approved in bold)

• Generalized tonic-clonic and complex partial seizures (monotherapy or adjunctive in adults and children)

• Treatment of seizures during or following neurosurgery

• Status epilepticus

• Trigeminal neuralgia

• Glossopharyngeal neuralgia

• Migraine prophylaxis

• Diabetic neuropathic pain

• Junctional epidermolysis bullosa

• Preeclampsia (alternative to magnesium sulfate)

• Cardiac arrhythmias (especially glycosideinduced)

• Seizure prophylaxis after severe traumatic brain injury

• Myotonia

How the Drug Works

• Primarily through the reduction of hyperexcitability on sodium channels

• May modulate T-type calcium channels, but not in the thalamus (unlike AEDs used for absence seizures)

How Long Until It Works

• Seizures: may decrease by 2–3 weeks

• Trigeminal neuralgia: may start working in hours to weeks

If It Works

• Seizures: goal is the remission of seizures. Continue as long as effective and well tolerated. Consider tapering and slowly stopping after 2 years without seizures, depending on the type of epilepsy

• Pain: goal is the reduction of pain severity and frequency. If trigeminal neuralgia remits on medication, periodically attempt to lower dose or discontinue

If It Doesn't Work

• Increase to highest tolerated dose

• Epilepsy: consider changing to another agent, adding a second agent, using a medical device, or a referral for epilepsy surgery evaluation. When adding a second agent, keep drug interactions in mind. Check level if seizures worsening and compliance is an issue

• Pain: try an alternative agent

Best Augmenting Combos for Partial Response or Treatment-Resistance

• Epilepsy: keep in mind drug interactions and their effect on levels

Tests

• During IV administration, continuous heart monitoring is required, with frequent blood pressure checks

• Obtain CBC monthly for the first few months due to risk of blood dyscrasias