Do antiepileptic drugs differ in suppressing interictal epileptiform activity in children?

Antiepileptic drugs may suppress interictal epileptiform activity in addition to suppressing seizures, although the comparative rates of suppression of interictal epileptiform activity for phenobarbital (PHB), carbamazepine (CBZ), and valproate (VPA) in children are unknown. Electroencephalogram (EEG) pairs were identified in which the first tracing illustrated interictal epileptiform activity before antiepileptic drug treatment; the rate of clearance of such activity in the subsequent tracing was assessed according to the drug introduced. EEG pairs (n = 213) were identified for CBZ, PHB, and VPA. Overall suppression rates of epileptiform activity in the second EEG were 12/55 (22%) for PHB, 27/81 (33%) for CBZ, and 35/77 (46%) for VPA (P = 0.005 for VPA vs PHB). When suppression rates were assessed comparing sleep-state pairs, suppression rates were 24/80 (30%) for PHB, 51/129 (40%) for CBZ, and 60/120 (50%) for VPA (P = 0.005 for PHB vs VPA). A subanalysis for focal discharges yielded suppression rates of 10/43 (23%) for PHB, 19/60 (32%) for CBZ, and 8/19 (42%) for VPA; for generalized discharges, 2/12 (17%) for PHB, 8/21 (38%) for CBZ, and 27/58 (47%) for VPA. VPA, and to a lesser extent CBZ, appeared superior to PHB in suppressing interictal epileptiform activity, including both focal and generalized epileptiform activity.