A Case of Valproate Overdose Complicated by Severe Hyperammonemia that was Ameliorated with Time Concomitant with Decline in Serum Valproate Concentration

摘要

A 26-year-old man treated for epilepsy with sodium valproate (VPA-Na, 800 mg/day) was admitted to the emergency room with dehydration, poor appetite, fatigue, arthralgia and general malaise. He stated that he had taken 50 VPA-Na tablets at 12: 00 midnight because he was hungry. Clinical findings on admission included blood pressure, 106/60 mmHg; body temperature, 36.9°C ； percutaneous oxygen saturation, 98% ； plasma total protein, 5.9 g/dL; and plasma ammonia level, 291 mug/dL. Markers of hepatic and renal functions and amylase levels were all within normal ranges. Serum total and free VPA concentrations at 16 h after VPA-Na ingestion were respectively 218 and 98mug/mL， decreasing to 122 and 31 mug/mL at 31 h， and 66 and 11 mug/mL at 55 h after ingestion. Plasma ammonia level correlated linearly with both serum total and unbound VPA concentrations, but the correlation coefficient (r) for the latter (0.980) tended to be greater than that for the former(0.998). These results suggest that serum unbound VPA concentration may be a better biomarker for predicting the time course of hyperammonemia in patients with VP A intoxication.