Carnitine

To the Editor:

The excellent review on valproic acid toxicity by Dr. Sztajnkrycer was both timely and informative [1]. Thus, we want to comment on the recommendation to use L‐carnitine supplementation for the management of valproic acid intoxication and hyperammonemia. First, there are no controlled studies evaluating this agent for these indications, and the appropriate dose and route of L‐carnitine supplementation needs to be determined [1]. Second, it has not been approved by the Food and Drug Administration (FDA) for this indication [2]. In addition, both the manufacturer, Sigma‐Tau Pharmaceutical (Gaithersburg, MD), and the FDA have issued warnings that seizures have been reported to occur in patients without a history of preexisting seizures who were treated with therapeutic doses of L‐carnitine in both oral or intravenous formulations [3]. As a result, we have not recommended L‐carnitine supplementation for the management of valproic acid intoxication or hyperammonemia for the last 4 years at our center. During that time period, we have successfully managed 38 patients with valproic acid intoxication without L‐carnitine supplementation. All recovered with symptomatic and supportive care. We believe that potential risk of this medication may outweigh the theoretical benefits proposed at this time. We would not advise L‐carnitine for the management of valproic acid intoxication and hyperammonemia until more data become available.