High-Flux Hemodialysis without Hemoperfusion is Effective in Acute Valproic Acid Overdose

OBJECTIVE:

To report a case of valproic acid overdose treated successfully with high-flux hemodialysis without the addition of charcoal hemoperfusion.

CASE SUMMARY: A 25-year-old white woman with a history of multiple suicide attempts and schizophrenia presented after ingesting an unknown amount of valproic acid. She became comatose and developed hypotension and lactic acidosis as valproic acid concentrations increased to >1200 μg/mL (therapeutic concentration 50–100). High-flux hemodialysis was performed for four hours; the calculated elimination rate constant (k_el) during the procedure was 0.2522 h⁻¹ with a half-life (t_1/2) of 2.74 hours compared with posthemodialysis k_el of 0.0296 h⁻¹ and t_1/2 of 23.41 hours, suggesting that high-flux hemodialysis effectively eliminates valproic acid. The patient's hemodynamic status and mental function improved in conjunction with the acute reduction in valproic acid concentrations. Her subsequent hospital course was complicated only by transient thrombocytopenia.

DISCUSSION: Most literature reports of valproic acid overdose have described the use of charcoal hemoperfusion alone or in combination with hemodialysis to accelerate valproic acid clearance at toxic concentrations. However, the pharmacokinetic properties of valproic acid indicate that hemodialysis alone would be effective therapy for an acute valproic acid overdose.

CONCLUSIONS:

We suggest that toxic concentrations of valproic acid can be effectively reduced with high-flux hemodialysis without the addition of charcoal hemoperfusion and its attendant risks.