- Participants taking an enzyme-inducing anti-epileptic drug (EIAED): phenobarbital, phenytoin, fosphenytoin, primidone, carbamazepine, oxcarbazepine, eslicarbazepine, rufinamide, and felbamate. Participant must be off any EIAEDs for at least two weeks prior to starting study drug. A list of EIAED and other inducers of CYP3A4 is provided in Table C-3 of Appendix C of the protocol.