Sodium Valproate-Induced Hyperammonemia: A Case Series in a Tertiary Care Hospital

Sodium valproate (VPA) is an extensively used anti-convulsant, which is an effective drug for treatment of epilepsy in adults and children, as well as for conditions like migraine, bipolar disorder, mania, and trigeminal neuralgia. Sedation, vertigo, ataxia, dose-dependent tremors, headaches, and gastrointestinal side effects are the most often reported adverse effects associated with VPA. A potential life-threatening event reported with VPA is hyperammonemia (HA), which is defined as an increase in serum level of ammonia. Only 587 reported cases of HA were found in the VigiAccess database, representing a mere 0.6% of the 95,000 reported adverse events linked to VPA. Hence, this case series was conducted with emphasis on monitoring of increased serum ammonia levels with or without hepatic enzymes increase for patients who are on VPA.

To assess elevated serum ammonia levels following VPA administration, and to ascertain the percentage of individuals with hepatic enzymes increased who took VPA and subsequently had elevated serum ammonia levels.

This study was conducted at the adverse drug reaction (ADR) monitoring centre (AMC) of the Pharmacovigilance Programme of India (PvPI) and Department of Psychiatry, Christian Medical College and Hospital (CMC&H), Ludhiana. The study comprised of 12 patients who were exclusively on VPA and exhibited symptoms related to elevated serum ammonia. An informed consent form (ICF) was provided to the patient prior to taking their personal details. Laboratory investigations were done to establish the diagnosis and liver function tests (LFTs), chiefly ALT (alanine transferase) and AST (aspartate aminotransferase) were also performed. It is a descriptive study which was for a time period of six months.  Results: This study includes 12 patients who had HA confirmed by laboratory investigation. Out of these 12 patients, two patients (17%) had a corresponding increase in LFT. The average as of the patients was 53.08 years and average serum ammonia levels were 219.15. None of the patients who presented with HA progressed to hyperammonemic encephalopathy (HAE).

This case series on valproate-induced HA should be of interest to psychiatrists, physicians, internists, family medicine physicians, hospitalists, and surgeons who will have patients on VPA. Delay in recognition of HA can result in the development of potentially life-threatening complications. Rapid diagnosis and management will help in reducing the number of cases which progress to encephalopathy which is highly fatal.