Phenobarbital in the prophylaxis of late posttraumatic seizures.

390 patients with severe head injuries were treated with phenobarbital (PB) orally for a period of 12 months in order to determine whether this drug could reduce the incidence of posttraumatic epilepsy (PTE). An intramuscular PB dose of 2.5-3 mg/kg body weight per day was administered within 24 hours after the trauma; after 5 days, or longer if the coma persisted, the drug was administered orally. Maintenance dosage adjustments, when necessary, were based on serial plasma concentrations of the drug, sustained at between 5 and 30 micrograms/ml. 293 patients completed the study. 66% of these presented one risk factor, while 34% presented two or more. 6 patients (2.04%) had at least one seizure during the twelve months. Plasma drug levels at the time of the seizure, with one exception of 15 micrograms/ml, ranged from 20 to 28 micrograms/ml. The results of the study indicate that PB administered during the first twelve months after the trauma, even at relatively low doses, can have a prophylactic effect on PTE.