In the PB group, a loading dose of 20 mg/kg (may give an additional 10 mg/kg) begins at a rate of 50 mg/min followed by IV 100 mg q6 h.

In the VPA group, a loading dose of 30 mg/kg (may give an additional 15 mg/kg) begins at a rate of 3 mg/kg per min followed by a continuous infusion at a rate of 1-2 mg/kg per hour.

In the PB group, a loading dose of 20 mg/kg (may give an additional 10 mg/kg) begins at a rate of 50 mg/min followed by IV 100 mg q6 h.

The primary study endpoint is the number of patients with effective seizure control, defined as a cessation of clinical and electroencephalographic seizure activity within 1 h after administration of the phenobarbital or valproate loading dose. Effective control of GCSE is assessed clinically by one certified neurologist and also confirmed with EEG by one certified electroencephalographer.

Neurologic outcome is assessed both at 30 days and at 3 months by one physician unaware of the therapeutic assignment through a phone interview or scheduled follow-up clinic visit. Mortality of each group is recorded at 30 days and at 3 months, respectively.

Adverse events are recorded as follows: systolic blood pressure lower than 90 mmHg, pulse lower than 50 beats/ min, arrhythmia (except supraventricular tachycardia), respiratory depression (arterial oxygen saturation below 90%, partial pressure of oxygen below 60 mmHg, or partial pressure of carbon dioxide above 60 mmHg), drug-induced liver disease (alanine aminotransferase or total bilirubin increase of more than twice the upper limit of the normal range), elevation of blood ammonia (more than twice the upper limit of the normal range), gastric motility insufficiency, bone marrow suppression (leukocytopenia, neutrocytopenia, thrombocytopenia or anemia), coagulation disorders, or drug-related sedation. The time to record adverse events is from the administration of PB or VPA to 1 week.