[Valproate-induced hyperammonemic encephalopathy. Review of cases in the psychiatric setting]

Valproate-induced hyperammonemic encephalopathy is a rare but severe and potentially fatal adverse event. Frequently, the use of valproic acid produces an elevation of ammonia levels. In some people, this is associated with the development of encephalopathy without evidence of liver failure, usually reversible with discontinuation or dose reduction. Although there is important evidence about this adverse event in patients with neurologic disorders, the data in the psychiatric setting is scarce. We review the available studies and case reports about valproate-induced hyperammonemic encephalopathy in people treated with valproic acid for psychiatric disorders. We describe the clinical and therapeutic characteristics, and the physiology of this adverse event.