Phenytoin toxicity associated with hypoalbuminemia in critically ill patients.

Four critically ill patients developed phenytoin toxicity. Hypoalbuminemia or concomitant displacing drugs resulted in an increased fraction of unbound drug. Clinical findings included gradual decrease in level of consciousness and cerebellar signs. Marked phenytoin toxicity can occur in critically ill patients with hypoalbuminemia and can often be detected only by direct measurement of free phenytoin levels.