I had a seizure in 1993, was given dilantin and it worked except for when the dose was lowered. Since December of 2011 I have had 3 gran mals after keppra was added as the dose was increased to 6000 mg a day. I'm weaning off now and staying on dilantin. Just wanted to know if dilantin's effectiveness is lowered by levetiracetam even though it is in the therapeutic range. Also it is generic levetiracetam and the manufacturers switched 4 times since I started taking the med.