This discussion has been published as a research paper
TDX-2026-00009
Phenobarbital-resistant neonatal seizures: levetiracetam vs phenytoin as second-line?
3-day-old term neonate with HIE grade II (Sarnat staging), currently on therapeutic hypothermia. Developed clinical and electrographic seizures despite phenobarbital 40 mg/kg load.
aEEG showing persistent seizure burden. Baby is intubated, hemodynamically stable. MRI scheduled after rewarming.
Questions:
- Levetiracetam vs phenytoin as second-line in neonatal seizures?
- Dosing of levetiracetam in neonates differs significantly from adults. What do you use?
- Should we aim for seizure freedom on aEEG or accept reduced seizure burden?
- Impact of therapeutic hypothermia on AED pharmacokinetics?
2 Answers
After reviewing with our neonatology and pediatric neurology teams, we went with levetiracetam as second-line. The NEOLEV2 trial (2019) showed comparable efficacy to phenobarbital as first-line, and the side effect profile is significantly better than phenytoin in neonates.
Dosing: 40 to 60 mg/kg IV load, then 10 to 30 mg/kg/day in two divided doses. We started at 40 mg/kg load and 20 mg/kg/day maintenance.
aEEG target: We aim for electrographic seizure freedom if achievable without excessive sedation. However, in HIE, breakthrough subclinical seizures are common during hypothermia and tend to resolve after rewarming. Our threshold for adding a third agent is continuous seizure activity exceeding 50% of a 1-hour epoch on aEEG.
Hypothermia PK effect: Therapeutic hypothermia reduces hepatic metabolism by roughly 25%. For phenobarbital (hepatically cleared), this means higher serum levels than expected. We check phenobarbital levels 24 hours after loading and target 30 to 40 mcg/mL. Levetiracetam is renally cleared, so hypothermia has less impact on its pharmacokinetics, though GFR is also mildly reduced.