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Valproate-Induced Hyperammonemic Encephalopathy in General Hospital Patients With One or More Psychiatric Disorders
Chandani Lewis1, George E Tesar1, Roman Dale1
1Department of Psychiatry and Psychology, Neurological Institute, Cleveland Clinic, Cleveland, OH.
Background:
Divalproex sodium/valproic acid (VPA) is an antiepileptic drug approved for use in epilepsy and bipolar disorder. Valproate-induced hyperammonemia occurs in up to 50% of VPA-treated patients, some of whom may become encephalopathic. Valproate-induced hyperammonemic encephalopathy (VHE) is thought to be rare, and for a variety of reasons, the diagnosis requires a high index of suspicion.
Objective:
The study's goals are to determine how common VHE is, and the quality of treatment provided when diagnosed.
Methods:
Retrospective, cross-sectional survey of general hospital patients. The hospital's laboratory and pharmacy databases were combined to identify a cohort of all VPA-treated patients who developed hyperammonemia during a 5-year period. Hospital records of the subset of patients with a psychiatric disorder were selected and reviewed for data collection.
Results:
Twenty of 793 (2.52%) VPA-treated patients had signs and symptoms consistent with VHE. The majority were White males on multiple psychotropic agents. Valproate was appropriately discontinued in 8 (40%) patients. Lactulose was the only ammonia-lowering drug used, and it was administered to 6 patients and only one among them had VPA discontinued.
Conclusion:
Study results indicate that VHE may be more common in psychiatric patients than previously assumed but underrecognized and inadequately treated. The diagnosis of VHE requires a high index of suspicion. Outcome is favorable once it is recognized and treated appropriately.