Management of Elevated Phenytoin Levels

Clinical Manifestations and Monitoring

• Nystagmus is a dose-related adverse effect that commonly occurs with elevated levels 1
• Cardiovascular complications, such as arrhythmias and hypotension, are rare with oral ingestion but can occur with IV administration, and monitoring vital signs is crucial, particularly if phenytoin was given intravenously 1, 2

Drug Interactions and Contributing Factors

• Drug interactions that inhibit phenytoin metabolism or displace it from protein binding can contribute to elevated levels, and medications that increase phenytoin levels include isoniazid, clarithromycin, and rifabutin 3, 4

Alternative Treatment Options

• Consider switching to alternative antiepileptic drugs, such as carbamazepine, oxcarbazepine, valproate, or levetiracetam, in patients susceptible to balance disturbances, cognitive dysfunction, or those with intellectual disability 2, 5