Use of multiple-dose activated charcoal in phenytoin toxicity

OBJECTIVE: To report a case of phenytoin toxicity successfully treated with multiple-dose activated charcoal. CASE SUMMARY: A 36-year-old man was first admitted with chronic phenytoin toxicity secondary to hepatitis and was treated symptomatically. His serum phenytoin concentration was 149.8 mumol/L on admission and decreased slowly over his 6-day hospitalization to 134.8 mumol/L. Upon readmission approximately 24 hours later, his phenytoin concentration was 186.7 mumol/L. Because of acute phenytoin toxicity, he was treated with multiple-dose activated charcoal. His phenytoin concentration after four doses of activated charcoal returned to the therapeutic range within 36 hours and his symptoms abated quickly, thus decreasing his hospital stay. DISCUSSION: The exact mechanism of action of multiple-dose activated charcoal to decrease serum phenytoin concentrations is unknown. Several mechanisms of action have been reported in the literature and are discussed. CONCLUSIONS: Multiple-dose activated charcoal was used successfully in treating acute phenytoin toxicity in our patient. Based on his previous admission for chronic phenytoin toxicity, his hospital stay was reduced by three days. The use of multiple-dose activated charcoal in acute phenytoin toxicity has potential therapeutic and financial implications.