Efficacy, safety, and pharmacokinetics of intravenous midazolam in Japanese children with status epilepticus.

Background: No dosing regimen has been established for the initial treatment of pediatric status epilepticus with intravenous midazolam. We therefore evaluated the efficacy, safety, and pharmacokinetics of bolus and continuous midazolam infusion.

Methods: This open-label, prospective, multicenter study involved 34 Japanese children with status epilepticus unresponsive to diazepam. An initial bolus of 0.15 mg/kg midazolam was given, with additional doses of 0.1-0.3 mg/kg up to a cumulative dose of 0.6 mg/kg. A continuous infusion was initiated at 0.1 mg/kg/h (maximum 0.4 mg/kg/h) for patients at high risk of recurrence or in whom seizure reduction was achieved, and continued for 24 h after seizure cessation. Seizure cessation was assessed based on clinical observation (disappearance of motor symptoms regardless of recovery of consciousness), rather than the disappearance of electroencephalography abnormalities.

Results: The seizure cessation rate with bolus midazolam was 88%. The cumulative dose was ≤0.3 mg/kg in 90% of patients who responded to bolus administration. Adverse events were observed in three patients; one had mild respiratory depression that required supplemental oxygen and bag-valve-mask ventilation. Elimination half-life was 0.999 ± 0.241 h in seven patients. Total body clearance ranged from 423 to 1220 mL/h/kg in older children but was notably higher in a 10-month-old infant (2010 mL/h/kg).

Conclusions: The efficacy and safety of midazolam were demonstrated in children with status epilepticus, suggesting that intravenous midazolam is suitable as first-line treatment.