Drug Interaction Report

MONITOR: Miconazole may increase plasma hydantoin concentrations. Phenytoin toxicity has been reported with concurrent parenteral and oral miconazole. The mechanism may be related to inhibition of hepatic CYP450 2C9, the major metabolic pathway for phenytoin.

MANAGEMENT: If miconazole and hydantoins must be used concomitantly, caution is recommended, as is close observation for clinical and laboratory evidence of altered phenytoin effect. Patients should be advised to notify their physician if they experience symptoms of possible hydantoin toxicity, including drowsiness, visual disturbances, change in mental status, seizures, nausea, or ataxia.