Acute Valproic Acid Poisoning in Young Children

Abstract

Objective:

To assess the signs and symptoms of acute valproic acid (VPA) overdose in young children.

Methods:

The medical records of previously healthy children admitted to the pediatric department for accidental acute VPA poisoning during the years 1995–1999 were evaluated retrospectively. Information was retrieved on serum VPA concentrations, signs and symptoms on admission and during hospitalization, electrocardiography findings, and laboratory tests.

Results:

All 16 children included in the study were in the age range of two to six years. In 13 cases, the drug had been intended for use by a family member and was ingested accidentally by the child. Three children were receiving VPA to treat a seizure disorder and had an adverse reaction due to unintentional overdose. For four children, a diagnosis of VPA poisoning was not made on admission because of inadequate history and was revealed only on toxicology screening. Drowsiness occurred in all the children, hypotonia in 11, ataxia in eight, miosis in six, and mild hypernatremia in five. Only two children had mildly elevated hepatic enzymes. The peak VPA serum concentrations in the study group ranged from 128 to 142 μg/mL (mean ± SD 135 ± 4.25; therapeutic range 50–100).

Conclusions:

Drowsiness was the most common symptom in young children with mild to moderate VPA poisoning. Other symptoms included hypotonia, ataxia, and miosis. A third of the patients had hypernatremia, most probably due to VPA formulated as sodium valproate. Unlike in cases of chronic toxicity, hepatic damage was not a characteristic finding.