Hyperammonemic Encephalopathy due to Valproic Acid and Topiramate Interaction

Unusual case of sodium valproate-induced hyperammonaemia encephalopathy

There is limited information about sodium valproate-induced hyperammonaemia encephalopathy (VPAIHE). The aim of this case report is to provide medical practitioners with a greater awareness of the possible development of hyperammonaemia due to sodium valproate use and its associated complications.This paper describes a middle-aged man with a history of bipolar affective disorder who was admitted with a manic relapse secondary to medication non-compliance. His admission was complicated by an intensive care unit admission to manage medical compromise in the context of sodium VPAIHE.

Valproic acid-induced encephalopathy: A review of clinical features, risk factors, diagnosis, and treatment

Valproic acid (VPA), or sodium valproate, is a commonly used medication for seizure disorders, migraines, and mental illness. Although VPA is relatively safe, it still has several adverse effects; among these, VPA-induced encephalopathy is the most serious. Valproic acid-induced encephalopathy mainly manifests as acute or subacute encephalopathy and has been associated with hyperammonemia, L-carnitine deficiency, and urea cycle enzyme dysfunction. Delayed identification of VPA-induced encephalopathy could be potentially fatal. Here, we perform an extensive review of relevant literature pertaining to VPA-induced encephalopathy, including its epidemiology, clinical features, possible pathophysiology, risk factors, diagnosis, and treatment.

Use of carglumic acid in valproate-induced hyperammonemia: 25 pediatric cases

Hyperammonemic encephalopathy is a rare but potentially dangerous complication of the antiepileptic drug (AED) sodium valproate (VPA). We report a retrospective study of 25 pediatric patients, (15 females [60%]; age: 7.6 ± 4.9 years), with different underlying disorders, who suffered from hyperammonemia due to VPA and who were treated with carglumic acid (CA). The duration of treatment with VPA was 15 ± 1 month, with a dose of 40 ± 16.6 mg/kg/d. VPA blood levels were 75.5 ± 60 mg/L with seven patients being overdosed (>100 mg/L). Twenty-three patients received concomitant treatment with other AEDs. The initial dose of CA was 100 mg/kg. Subsequently, CA doses of 25 mg/kg were given to 22 patients every 6 hours (average treatment length 2.17 ± 1.1 days) until ammonemia was normalized. In nine patients, CA was used in combination with other drugs to treat hyperammonemia. In all cases, blood ammonia levels were brought under control and symptoms of hyperammonemia resolved. Two hours after CA administration, the average reduction in ammonium levels was 53 ± 29 and 88.6 ± 47.5 μmol/L at 24 hours, resulting in a statistically significant decrease when compared to pretreatment levels. There were no statistically significant differences between sexes, in the presence or not of cognitive impairment or previous carnitine treatment. There were no statistically significant differences when comparing treatment with CA plus ammonia scavengers vs CA alone. In 17 patients (68%) VPA was discontinued and 62% of the patients who maintained treatment had recurrent episodes of hyperammonemia.

Carglumic Acid Treatment of a Patient with Recurrent Valproic Acid-induced Hyperammonemia: A Rare Case Report

Valproic acid, first manufactured as an anticonvulsant, is commonly used to treat both neurological and psychiatric conditions. A rare and deadly side effect of this medication is hyperammonemia, presenting as lethargy, confusion, seizure, and, ultimately, coma. In rare circumstances, hyperammonemia can be recurrent and devastating, especially in patients with an underlying N-acetyl glutamate synthase (NAGS) deficiency, as the valproic acid can enhance this enzyme deficiency and inhibit the conversion of ammonia into urea in the liver. For these subtypes of patients, the United States Food and Drug Administration (US FDA) has recently approved carglumic acid, a medication that can act as a scavenger by effectively increasing the levels of NAGS, ultimately enhancing the conversion of ammonia to urea. In our case report, we have mentioned a patient with treatment-resistant bipolar disorder, who presented with elevated ammonia levels secondary to valproic acid treatment. Valproic acid was the only drug that was effective in his case, so we initiated therapy to reduce his elevated ammonia levels. After a thorough evaluation, we found the patient had a genetic NAGS deficiency. Carglumic acid was initiated and proved efficacious in our patient.

Levocarnitine for valproate-induced hyperammonemia in the psychiatric setting: A case series and literature review

Introduction

Hyperammonemia is a potential adverse effect of valproic acid (VPA) therapy, which is often asymptomatic but can lead to severe, life-threatening encephalopathy. Carnitine deficiency due to VPA is the proposed mechanism for hyperammonemia and the development of VPA-induced hyperammonemic encephalopathy (VHE). Levocarnitine, the active form of carnitine, has been suggested for treatment and prevention of VHE.

Methods

Data was collected by chart review of 3 patients who received oral levocarnitine supplementation in the psychiatric setting for VPA-induced hyperammonemia. Review of the literature was performed through June 2017 using the following PubMed search terms: valproate, valproic acid, hyperammonemia, altered mental status, encephalopathy, and levocarnitine. Articles were included if they described use of levocarnitine in VPA-treated patients with psychiatric disorders.

Results

One patient developed encephalopathy with resolution of symptoms after VPA discontinuation. Valproic acid was restarted with the addition of levocarnitine to prevent VHE reoccurrence. In the other 2 cases, levocarnitine was started prophylactically in patients who developed hyperammonemia without emergence of any clinical symptoms. Ammonia levels were reduced to normal in all cases, and no symptoms consistent with encephalopathy were reported. The literature search identified 6 additional cases with 5 of 6 reports supporting use of levocarnitine for decreased ammonia levels as well as an observational trial.

Discussion

This literature review and case series illustrates successful use of levocarnitine supplementation for reduction of ammonia levels in the setting of VPA-induced hyperammonemia among patients with psychiatric disorders. However, clinical significance of ammonia reduction in asymptomatic patients is difficult to determine.

Hyperammonemia and lactic acidosis in adults: Differential diagnoses with a focus on inborn errors of metabolism

The adult endocrinologist may be asked to consult on a patient for unexplained biochemical disturbances that could be caused by an underlying inborn error of metabolism. A genetic disorder is generally less likely to be the cause as these disorders are individually rare, however inborn errors of metabolism are collectively not infrequent and important to consider as they may be treatable and tragic outcomes avoided. Hyperammonemia or lactic acidosis are most often secondary markers of an acquired primary disease process, but they may be a clue to the presence of a genetic disorder. Herein is presented an approach to the differential diagnosis of elevated ammonia and lactate, and a brief discussion of management for when an inborn error is diagnosed.

Reversible Encephalopathy due to Valproic Acid Induced Hyperammonemia in a Patient with Bipolar I Disorder: A Cautionary Report

Valproic acid (VPA) is an FDA-approved medication widely prescribed for seizures, migraines, and mixed or manic episodes in bipolar disorder. Hyperammonemia is a rare complication of VPA use, which can result in high morbidity and occasionally fatal encephalopathy. The scant literature on Valproate Induced Hyperammonemic Encephalopathy (VIHE) is characterized by acute onset of decreasing level of consciousness, drowsiness, lethargy which in rare instances can lead to seizures, stupor, coma, and persistent morbidity and cortical damage. Below we describe a case report of a patient with Bipolar I Disorder with no primary evidence of hepatic dysfunction that was initiated on VPA and olanzapine to address manic and psychotic symptoms. This patient subsequently developed elevated ammonia (NH4) levels that led to a reversible encephalopathy. This cautionary case report highlights the potential for a rare but serious complication from VPA, a medication increasingly used in both neurologic and neuropsychiatric settings. It is imperative that clinicians perform a thorough physical, neurological and diagnostic evaluation, routinely check NH4 and VPA levels when prescribing these agents and exercise caution when VPA is concomitantly prescribed with antipsychotics and cytochrome P450 inducing antiepileptic medications.

Valproic Acid Induced Hyperammonemia in a Long Time Treated Patient

We report a case of a patient who had been on long time valproic acid for treatment of bipolar affective disorder. While being an inpatient, serology ammonia level testing revealed a very high ammonia level despite being asymptomatic. Dual therapy of carnitine and lactulose was provided to the patient for treatment of the hyperammonemia. It should also be noted that, during this treatment, valproic acid was not stopped. Consequently, this case illustrates that patients can present asymptomatically despite very high ammonia levels and hyperammonemia can occur in chronic valproic acid despite not increasing the dose of the medication and psychiatrists do not need to discontinue valproic acid in the presence of elevated levels of ammonia if the patient shows no signs of encephalopathy or delirium.

Valproate Induced Delirium due to Hyperammonemia in a Case of Acute Mania: A Diagnostic Dilemma

Divalproex sodium is commonly used drug to treat variety of psychiatric and neurological disorders. Hyperammonemia is infrequent adverse affect of treatment with divalproex sodium. It needs high degree of clinical suspicion or else can lead to delirium of non hepatic origin in some group of patients and to medication errors or even death. We hereby report a case of mania who developed hyperammonemia with normal sodium valproate levels and liver function tests where delirium lead to diagnostic and medication errors. Withdrawal of divalproex sodium led to clinical recovery but delirium prolonged his hospital stay. This case report cautions the clinicians about hyperammonemia as the uncommon side effects and emphasizes the need of doing blood ammonia testing in patients treated with divalproex sodium where recovery is halted or clinical condition worsens despite normal liver function test and EEG.