A study of phenobarbital and dilantin in neonatal seizures.

A total of 40 cases of neonatal convulsions of different nonmetabolic aetiological factors were studied. Patients with kernicterus were included in the study. Peak plasma phenobarbital concentrations after incremental loading doses of phenobarbital i.e. 10 mg/kg, 15 mg/kg, and 20 mg/kg were determined. Diphenylhydantoin was added if phenobarbital alone was unable to control seizures. In three patients, a combination of phenobarbital and diphenylhydantoin was used as the initial loading therapy. Increase in the loading dose of phenobarbital was associated with an increase in its peak plasma concentration. Despite increase in the plasma phenobarbital concentration beyond the 'therapeutic' levels suggested by the Western studies, doses of 15 mg/kg and 20 mg/kg of phenobarbital were unable to score over the traditional regimen of 10 mg/kg. Convulsions were controlled in 50% of the patients with any of these three regimens, irrespective of the aetiology. Convulsions were controlled in 7 out of the 9 cases where diphenylhydantoin was added, because of the failure of phenobarbital in controlling the convulsions as a single drug. Convulsions of all the three patients, in whom a combination of phenobarbital and diphenylhydantoin was used by random selection as the initial bolus, were controlled. Seizure effects were difficult to distinguish from drug effects but major side effects were not encountered despite the fluctuating drug levels in the sick neonate.