Efficacy, Tolerability and Serum Phenytoin Levels after Intravenous Fosphenytoin Loading Dose in Children with Status Epilepticus

Objective To evaluate the efficacy and tolerability of intravenous fosphenytoin in children with status epilepticus, and resulting serum total phenytoin levels. Methods In this prospective study, 51 children aged less than 18 years received intravenous loading dose of fosphenytoin (18-20 mg/kg). Serum total phenytoin levels were estimated at 90 -100 minutes. Outcomes studied were (i) seizure control and local and/ or systemic adverse effects in next 24 hours and (ii) phenytoin levels and its correlation with dose received, seizure control and adverse effects. Results The actual dose of fosphenytoin received varied from 15.1 to 25 mg/kg. Seizures were controlled in 45 (88%) children and, two required additional dose of 10 mg/kg. None of the children showed any local or systemic adverse effects. Serum total phenytoin levels were in the therapeutic range (10-20 mu g/mL) in 12 (23.5%), sub-therapeutic in 16 (31.3%) and supratherapeutic in 25 (49%) children. There was weak correlation of the phenytoin levels with dose of fosphenytoin received, seizure control, or adverse effects. Conclusion Intravenous fosphenytoin loading dose of 20 mg/kg is effective in controlling seizures in 88% of children with status epilepticus, with a good safety profile. Seizure control and adverse effects appear to be independent of serum total phenytoin levels achieved.