CASE SUMMARY: This was the case of a 75-year-old Hispanic man (height, 145 cm; weight, 68 kg) who developed
hypotension after receiving an intravenous loading dose of
valproate sodium. The patient received the loading dose 12 hours after administration of his last dose of
phenytoin (300 mg daily), which had been discontinued secondary to a cutaneous
drug reaction. The patient's medical history was significant for
seizure disorder, a
cerebrovascular accident, and controlled
type 2 diabetes mellitus. He was taking
glyburide 5 mg daily and
aspirin 81 mg daily. At baseline, the patient's blood pressure (measured while seated, at rest, using an upper-extremity cuff) was 135/70 mm Hg. The intravenous loading dose of
valproate sodium (20 mg/kg) was administered at a rate of 14 mg/min (total dose, 1280 mg over 90 min). Approximately 2.5 hours after completion of the loading dose, the patient's blood pressure decreased to 107/48 mm Hg. Because our standard operating procedure is to measure blood pressure every 4 hours after the baseline measurement, the patient's
hypotension was not detected during the infusion. The next morning (22 hours after completion of the
valproate sodium infusion),
divalproex sodium 1000 mg orally once daily was initiated as maintenance
therapy. The patient's blood pressure reached a nadir of 82/44 mm Hg. The
hypotension was treated initially with intravenous fluid hydration with
normal saline, but the blood pressure correction was transient using this approach. The patient remained hypotensive for 3 days. The
hypotension was ultimately found to be self-limited, and the patient was asymptomatic throughout his
hospital stay. The patient's Naranjo
adverse drug reaction probability scale score was 6, indicating that the relationship between
valproate sodium infusion and
hypotension was probable.
CONCLUSION: