Hyperammonemia in asterixis induced by carbamazepine: two case reports.

Two patients developed asterixis while they were taking carbamazepine at "therapeutic" levels. The only laboratory abnormality was slight hyperammonemia. It occurred with normal hepatic function as a dose-related effect. In fact, the blood ammonia level decreased and asterixis ceased when carbamazepine was stopped or reduced in dosage. The relationship between asterixis and hyperammonemia during carbamazepine therapy is discussed.