Use of meropenem to treat valproic acid overdose

Overdose of valproic acid (VPA) or its derivatives can cause significant toxicities such as hyperammonemia or altered mental status. While levocarnitine has been used historically to manage VPA-associated hyperammonemia, no standard of therapy exists to manage VPA toxicity. We present a case of VPA overdose managed with meropenem in addition to levocarnitine. A 38-year old female presented to the emergency department after intentionally ingesting 20 tablets of extended release divalproex sodium. She received a 4-gram loading dose of levocarnitine. She developed altered mental status, and a repeat VPA level yielded a result of 278 μg/mL. She was given 1 g of meropenem and her subsequent VPA level was 193 μg/mL. Approximately 8 h after the initial dose, another 1 g of meropenem was administered. Additionally, she received 1 g of levocarnitine every 4 h for a total of six doses. A repeat VPA level returned at 62 μg/mL. The patient was transferred to the intensive care unit for further management. Carbapenem antibiotics inhibit acylpeptide hydrolase in the gastrointestinal tract. Inhibition of this enzyme prevents the reabsorption of metabolized VPA and therefore causes increased elimination. Our patient demonstrated a rapid lowering of VPA levels after administration of meropenem.