The Poison Review

L-Carnitine for Acute Valproic Acid Overdose: A Systematic Review of Published Cases. Perrott J et al. Ann Pharmacother July/Aug 2010;44:1287-93.

Abstract

Valproic acid has a number of possible metabolic effects, including carnitine depletion leading to increased serum ammonia levels. The authors of this study set out to review and evaluate published evidence  concerning patients with acute valproic acid overdose treated with carnitine.  They consulted three large databases (Medline, Embase, and Google Scholar) encompassing 60 years of medical literature, and came up with  . . . all of eight cases. These eight patients were treated with various doses of carnitine given by different routes (IV or PO).  All recovered completely and no adverse effects related to carnitine were identified.

The authors admit that the lack of consistent data makes identifying an optimal dosing strategy “challenging”. (This is inarguable, if by “challenging” they really mean “impossible”.)  They also call for “more rigorous studies” into this issue without asking the obvious question: who would fund such studies, which — given the fact that almost all patients recover fully with standard care — would require enormous numbers of patients seen at multiple medical centers.  Finally, they conclude that carnitine should “be considered for patients with large, acute intestions of valproic acid  . . . who are demonstrating decreased level of consciousness”. Given that carnitine is inexpensive and relatively safe, this conclusion is not unreasonable, but it is not based on any science, and it was certainly not necessary to go through the charade of a “Systematic Review of Published Cases” to arrive at it.