What is the treatment for Phenytoin (Dilantin) overdose?

From the Guidelines

Treatment for Dilantin overdose requires immediate discontinuation of the medication and supportive care, with consideration of activated charcoal administration if ingestion was recent, and monitoring of vital signs, cardiac function, and neurological status. The management of Dilantin (phenytoin) overdose is primarily focused on supportive care and reducing the absorption of the drug if the ingestion was recent. According to the study by 1, there is no specific antidote for phenytoin toxicity, and the treatment involves managing symptoms and preventing further complications.

Key Considerations in Management

• Discontinuation of the medication to prevent further toxicity
• Administration of activated charcoal if the ingestion was within 1-2 hours to reduce absorption
• Monitoring of vital signs, cardiac function, and neurological status to quickly identify and manage any complications
• Use of benzodiazepines like lorazepam (0.05-0.1 mg/kg IV) to manage seizures if they occur, as mentioned in the study by 1
• Treatment of hypotension with IV fluids and vasopressors such as norepinephrine if necessary
• Consideration of hemodialysis for severe toxicity, although its effectiveness is limited due to phenytoin's high protein binding

Monitoring and Supportive Care

• Regular monitoring of blood levels until they return to the therapeutic range (10-20 μg/mL)
• Supportive care for symptoms such as ataxia, nystagmus, slurred speech, confusion, and in severe cases, coma and respiratory depression
• Recognition that symptoms may persist for several days due to the drug's long half-life (22-36 hours), necessitating continued supportive care until the drug is cleared from the system. The study by 1 provides guidance on the management of antiepileptic medications, including phenytoin, in the emergency department setting.

From the FDA Drug Label

The lethal dose in pediatric patients is not known. The lethal dose in adults is estimated to be 2 to 5 grams. The initial symptoms are nystagmus, ataxia, and dysarthria. Other signs are tremor, hyperreflexia, lethargy, slurred speech, nausea, vomiting. The patient may become comatose and hypotensive. Death is due to respiratory and circulatory depression Treatment is nonspecific since there is no known antidote. The adequacy of the respiratory and circulatory systems should be carefully observed and appropriate supportive measures employed Hemodialysis can be considered since phenytoin is not completely bound to plasma proteins. Total exchange transfusion has been used in the treatment of severe intoxication in pediatric patients.

Treatment for Dilantin overdose is nonspecific and focuses on supportive care. The main goals are to:

• Carefully observe the respiratory and circulatory systems
• Employ appropriate supportive measures
• Consider hemodialysis as an option
• In severe cases, particularly in pediatric patients, total exchange transfusion may be used 2

From the Research

Treatment for Dilantin Overdose

• The mainstay of therapy for a patient with phenytoin intoxication is supportive care, including attention to vital functions, management of nausea and vomiting, and prevention of injuries due to confusion and ataxia 3.
• There is no antidote for phenytoin overdose, and no evidence that any method of gastrointestinal decontamination or enhanced elimination improves outcome 3.
• Activated charcoal should be considered if the patient presents early, but the role of multiple-dose activated charcoal is controversial 3, 4.
• Experimental studies have shown increased clearance rates with multiple-dose activated charcoal, but this effect has not been translated into clinical benefit 3.
• Invasive methods of enhanced elimination, such as plasmapheresis, hemodialysis, or hemoperfusion, may be considered in severe cases, but their effectiveness is debated 3, 5.
• A study found that hemodiaperfusion with activated charcoal can be a reasonable measure for forced lowering of highly toxic phenytoin plasma concentration, especially in cases of intravenous overdose 5.
• Another study found that multiple-dose activated charcoal may decrease the time to reach a subtoxic level of phenytoin in patients with supratherapeutic phenytoin levels, but further study is needed to confirm this finding 4.

Supportive Care

• Supportive care is crucial in managing phenytoin overdose, including monitoring of vital signs, management of nausea and vomiting, and prevention of injuries due to confusion and ataxia 3.
• Nurses should be thoroughly familiar with the properties of phenytoin and its potential side effects and interactions to practice safely 6.