Efficacy of once daily dosing with phenobarbital in children with seizure disorders

One of the first-line drugs in the therapy of seizure disorders in pediatrics is phenobarbital. Frequently it is used alone when seizures can be controlled with a single drug, however, its use in combination with other anticonvulsants is also prevalent. According to Buchthal, phenobarbital should be the first medication tried for grand mal and focal seizure and in infants is superior to phentoin for febrile seizures. However, psychomotor and petit mal seizures seldom respond and occasionally maybe made worse. The current literature has a paucity of studies involving phenobarbital pharmacokinetics in children between the ages of one to 14 years. It has been suggested that their half-life is age-dependent, falling in the range of 37-133 hours which is comparable to the range reported for adults (53-140 hours). Because of the prolonged half-life, it seems reasonable to recommend once daily dosing for children and indeed Livingston mentions this possibility. However, Svensmark and Buchthal suggested a twice daily dosage for children based on the assumption that they maintain an increased rate of elimination of phenobarbital doses for children. The present practice of twice a day dosing of phenobarbital based on Svensmark and Buchthal's work is open to question because of questionable data interpretation in their report. The purpose of this investigation was to evaluate the appropriateness of once daily dosing of phenobarbital in children with seizure disorders.