L-Arginine in the treatment of valproate overdose - five clinical cases

Drug-induced hyperammonaemia

Hyperammonaemia (HA) as a consequence of numerous primary or secondary causes, gives rise to clinical manifestations due to its toxic effects on the brain. The neurological consequences broadly reflect the ammonia level, duration and age, with paediatric patients being more susceptible. Drug-induced HA may arise due to either decreased ammonia elimination or increased production. This is associated most frequently with use of valproate and presents a dilemma between ongoing therapeutic need, toxicity and the possibility of an alternative cause. As there is no specific test for drug-induced HA, prompt discussion with a metabolic physician is recommended, as the neurotoxic effects are time-dependent. Specific guidelines for managing drug-induced HA have yet to be published and hence the treatment approach outlined in this review reflects that outlined in relevant urea cycle disorder guidelines.

Recomendaciones de manejo de la hiperamonemia en neonatos

La hiperamonemia se define como el aumento de las concentraciones de amonio en el plasma, de forma aguda o crónica. Frecuentemente, se presenta en diversos tipos de errores innatos del metabolismo, enfermedades que deben diagnosticarse y manejarse de manera inmediata y adecuada, debido a que el retraso en su manejo genera secuelas neurológicas graves y permanentes, así como desenlaces fatales. El objetivo del artículo es aportar herramientas al clínico para la sospecha, el abordaje diagnóstico y el manejo del recién nacido con hiperamonemia primaria, teniendo en cuenta la correlación entre fisiopatología, etiología, aproximación clínica y de laboratorio, así como recomendaciones de manejo farmacológico y no farmacológico.

Valproic acid affects fatty acid and triglyceride metabolism in HepaRG cells exposed to fatty acids by different mechanisms

Treatment with valproate is associated with hepatic steatosis, but the mechanisms are not fully elucidated in human cell systems. We therefore investigated the effects of valproate on fatty acid and triglyceride metabolism in HepaRG cells, a human hepatoma cell line. In previously fatty acid loaded HepaRG cells, valproate impaired lipid droplet disposal starting at 1 mM after incubation for 3 or 7 days. Valproate increased the expression of genes associated with fatty acid import and triglyceride synthesis, but did not relevantly affect expression of genes engaged in fatty acid activation. Valproate impaired mitochondrial fatty acid metabolism by inhibiting β-ketothiolase and the function of the electron transport chain, which was associated with increased mitochondrial reactive oxygen species production. Valproate increased the mitochondrial DNA copy number per HepaRG cell, possibly as a consequence of impaired mitochondrial function. Valproate decreased the hepatocellular mRNA and protein expression of the fatty acid binding protein 1 (FABP1) and of the microsomal triglyceride transfer protein (MTTP) at 1 mM and increased the hepatocellular concentration of free fatty acids. Furthermore, valproate decreased protein expression and excretion of ApoB100 in HepaRG cells at 1 mM, reflecting impaired formation and excretion of very low-density lipoprotein (VLDL). In conclusion, valproate increased the hepatocellular triglyceride content by multiple mechanisms, whereby impaired expression of FABP1 and MTTP as well as impaired VLDL formation and excretion appeared to be dominant. Valproate caused cell death mainly by apoptosis, which may be a consequence of mitochondrial oxidative stress and increased hepatocellular concentration of free fatty acids.

Hemodiafiltration Treatment for Severe Valproic Acid Intoxication: Case Report and Updated Systematic Literature Review

Background: Valproic acid (VPA) has been approved for the treatment of seizure disorders. It is also commonly used in psychiatric disorders, such as schizophrenia spectrum disorders. With increasing administration, reports of intoxications are more frequently reported. The most common findings of VPA intoxication are central nervous system depression, respiratory depression, hypotension, metabolic acidosis, and elevated lactate, among others. Methods: We describe a case report of VPA intoxication with hemodiafiltration (HDF) as extracorporeal treatment (ECTR) for removal of VPA. This treatment modality has only rarely been reported in the current literature. In addition, we performed an updated systematic literature review (SLR) of additional cases on the topic ranging from December 1st, 2014 to April 20th, 2018. We searched MEDLINE and Web of Science for relevant references. Results: In the presented case, VPA intoxication occurred in a 46-year-old female patient after oral ingestion of 56 g of VPA. In addition to vasopressors and endotracheal intubation, we administered L-Carnitine (L-Car) and performed hemodiafiltration treatment. After intravenous therapy with L-Car and simultaneous HDF sessions, we observed full recovery without neurological sequelae. The SLR identified 8 additional articles reporting favorable outcomes with extracorporeal treatments in most cases. Conclusion: HDF and other extracorporeal procedures are safe and effective therapeutic options in patients with VPA intoxication. The choice of ECTR modality mainly depends on local experience and the setting. In the present case, ingestion of 56 g was successfully treated with HDF. These findings are in line with several other case reports describing positive outcomes. Extracorporeal treatment, including HDF, should be considered early in the management of VPA intoxication. Supporting evidence is emerging, but it is of limited quality.