Abstract
Valproic acid-induced hyperammonemic encephalopathy is a rare yet serious adverse drug reaction. Medication interactions such a valproic acid and topiramate can precipitate an event. We present the case of a 52-year-old female that presented with acute mental status change and hypersomnolence due to hyperammonemia caused by a valproic acid derivative. The patient improved after withdrawal of the offending medications and treatment with lactulose. Clinicians should remain hypervigilant in monitoring for valproic acid-induced hyperammonemic encephalopathy and risk factors such as polypharmacy.
Highlights
Valproic acid (VPA) is considered one of the first line treatment agents for psychiatric conditions such as bipolar disorder [1]
Along with potential electroencephalography (EEG) findings, valproate-induced hyperammonemic encephalopathy (VHE) is commonly characterized by lethargy, vomiting, cognitive slowing, focal neurological deficits, and decreasing levels of consciousness ranging from drowsiness to coma in patients on VPA treatment [3, 4]
We present the case of a 52-year-old female that developed presumed VHE after the addition of VPA to her home medication of topiramate
Summary
Valproic acid (VPA) is considered one of the first line treatment agents for psychiatric conditions such as bipolar disorder [1]. Home medications were as follows: primidone 200 mg twice daily, Case Reports in Psychiatry topiramate 50 mg every morning and 100 mg every evening, paroxetine 30 mg daily, gabapentin 300 mg twice daily, quetiapine 50 mg every morning and 100 mg every evening, clonazepam 1 mg daily, and divalproex sodium 500 mg twice daily Due to her altered mental status and increasing somnolence, several laboratory and diagnostic tests were performed. Patient was discharged in stable condition to a psychiatric unit It was determined by internal medicine team as well as neurologist that acute encephalopathy was likely due to hyperammonemia induced by reinitiation of valproic acid and sedating effects of medications
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