Side effects of sodium valproate in monotherapy controlled by plasma levels: a study in 88 pediatric patients

The incidence of toxicity associated with the use of valproic acid (VPA) is considered remarkably low compared to other antiepileptic drugs. This study reports the toxicity of VPA administered as a single drug to 88 children in relation to the daily dose and drug plasma level. The frequency of side effects observed clinically was 42.0%, but it increased to 80.7% when a questionnaire was introduced. In spite of the limitations of this method, the results show the need to perform systematic surveillance for side effects of all antiepileptic drugs, similar to those made to assess their clinical effectiveness. Anorexia, vomiting, and sleep alterations were the most common side effects detected in the clinical record; patients who showed anorexia, hyperactivity, lassitude, sleep disturbances, and sadness had received daily doses significantly higher than patients not showing side effects. Similarly, the children who needed to reduce or discontinue the treatment were receiving the highest doses. No relations, however, could be established between the incidence of side effects and plasma levels of VPA except for lassitude and drowsiness. Severe or fatal toxicity was not detected.