Phenobarbital compared with phenytoin for the treatment of neonatal seizures

Background Seizures occur in 1 to 2 percent of neonates admitted to an inte nsive care unit. The treatment is usually with either phenobarbital or phen ytoin, but the efficacy of the two drugs has not been compared directly. Methods From 1990 to 1995, we studied 59 neonates with seizures that were c onfirmed by electroencephalography. The neonates were randomly assigned to receive either phenobarbital or phenytoin intravenously, at doses sufficien t to achieve free plasma concentrations of 25 mu g per milliliter for pheno barbital and 3 mu g per milliliter for phenytoin. Neonates whose seizures w ere not controlled by the assigned drug were then treated with both drugs. Seizure control was assessed by electroencephalographic criteria. Results Seizures were controlled in 13 of the 30 neonates assigned to recei ve phenobarbital (43 percent) and 13 of the 29 neonates assigned to receive phenytoin (45 percent; P = 1.00). When combined treatment is considered, s eizure control was achieved in 17 (57 percent) of the neonates assigned to receive phenobarbital first and 18 (62 percent) of those assigned to receiv e phenytoin first (P = 0.67). The severity of the seizures was a stronger p redictor of the success of treatment than was the assigned agent. Neonates with mild seizures or with seizures that were decreasing in severity before treatment were more likely to have their seizures end, regardless of the t reatment assignment. Conclusions Phenobarbital and phenytoin are equally but incompletely effect ive as anticonvulsants in neonates. With either drug given alone, the seizu res were controlled in fewer than half of the neonates. (N Engl J Med 1999; 341:485-9.) (C) 1999, Massachusetts Medical Society.