How do phenytoin, carbamazepine and phenobarbitone affect zonisamide exposure?

Phenytoin, carbamazepine and phenobarbitone induce CYP3A4 and lower zonisamide exposure in epileptic patients; this is unlikely to be clinically significant when zonisamide is added, but starting, stopping or adjusting these drugs may require zonisamide dose adjustment, and interaction studies were performed only in adults.