Carbamazepine (Tegretol, Tegretol-XR, Carbatrol)

AEDs that increase levels AEDs that decrease levels
felbamate (increases carbamazepine epoxide) felbamate
valproate (increases carbamazepine epoxide) phenobarbital
phenytoin primidone

Felbamate (Felbatol)

Felbamate is recommended for use only by patients who respond inadequately to alternative treatments and whose epilepsy is so severe that a substantial risk of aplastic anemia, liver failure, or both is deemed acceptable in light of the benefits of its use.

AEDs that increase levels AEDs that decrease levels
valproate carbamazepine
phenytoin phenobarbital

Gabapentin (Neurontin)

AEDs that increase levels AEDs that decrease levels
none none

Lamotrigine (Lamictal)

AEDs that increase levels AEDs that decrease levels
valproate carbamazepine
phenytoin phenobarbital

Levetiracetam (Keppra)

AEDs that increase levels AEDs that decrease levels
none none

Phenobarbital

AEDs that increase levels AEDs that decrease levels
valproate phenytoin (variable interaction)
phenytoin (variable interaction)  

Phenytoin (Dilantin, Phenytek)

AEDs that increase levels AEDs that decrease levels
ethosuximide (variably reported) carbazepine
felbamate  
oxcarbamazepine  
valproate (unbound levels)  
topiramate  

Tiagabine (Gabitril)

AEDs that increase levels AEDs that decrease levels
none carbamazepine
  phenytoin
  phenobarbital

Valproate (Depakote, Depakote ER, Depakene, valproic acid)

AEDs that increase levels AEDs that decrease levels
felbamate carbamazepine
  phenobarbital
  phenytoin

Adapted from: Schachter SC. Treatment of seizures. In: Schachter SC, Schomer DL, eds. The comprehensive evaluation and treatment of epilepsy. San Diego, CA: Academic Press; 1997. p. 61-74.
With permission from Elsevier (www.elsevier.com).

Authored By: 
Barry Gidal PharmD
PharmD
University of Wisconsin-Madison
Authored Date: 
01/2004