Antiseizure Drug Levels in Children Aged 2–12 Years Presenting With Breakthrough Seizures: A Single Center Cross-sectional Study

Objective To study the antiseizure drug levels and associated factors in children with breakthrough seizures. Methods This cross-sectional study conducted at a public hospital from November, 2017 to April, 2019, included 145 children with epilepsy aged 2 to 12 years presenting with breakthrough seizure. Antiseizure drug levels were measured, and the levels were categorized as within, below, and above the reference range. Results Children with epilepsy receiving sodium valproate, phenytoin and carbamazepine were 111 (73%), 31 (20.4%) and 10 (6.6%), respectively, of which 7 were receiving multiple antiseizure drugs. Drug levels below the reference range were found in 64 (44.1%), within the reference range in 70 (48.3%), and the above reference range in 11 (7.6%) children. Conclusion Nearly half the children with breakthrough seizures had sub-therapeutic levels, especially those on phenytoin therapy. Drug levels in below therapeutic range were not associated with occurrence of breakthrough seizures.