Interaction of oral phenytoin with enteral feedings.

A 48-yr-old man with squamous cell carcinoma of the lung, hypercalcemia, and brain metastases with seizures was treated with phenytoin. Constant nasogastric infusion with Osmolyte was begun for hydration and nutritional status, necessitating an increase in his phenytoin dosage. Adequate seizure control and phenytoin levels were obtained on this adjusted regimen. However, on the 16th hospital day, the patient pulled out his nasogastric tube and received two doses of phenytoin without Osmolyte. The patient became lethargic, and his phenytoin level was 53 micrograms/ml. The patient was placed on bolus nasogastric feedings and a lower dose of phenytoin administered between feedings. Adequate seizure control and appropriate phenytoin levels were obtained with no further problems. The recommended management of the phenytoin-enteral feeding interaction is to flush and clamp the nasogastric tube for 2 hr before and 2 hr after the phenytoin dose.