Any time a doctor suggests a new prescription, be sure to talk about what other medicines, supplements, herbs, and vitamins are already being taken. Sometimes one kind of medicine changes the way another kind of medicine works in the body. If two kinds of medicine affect each other, the doctor may prescribe something else or change the amount to be taken. The amount of Zarontin may need to be changed, for instance, if you take isoniazid or rifampin, medicines often used to treat tuberculosis.

Zarontin is less likely than many other seizure medicines to interact with other medications, however.

How does Zarontin affect other medicines?
Zarontin has little effect on other medications. It may slightly raise the amount of Dilantin or Phenytek (phenytoin) in the blood but the effect probably is not important.

How do other medicines affect Zarontin?
Depakote and other valproate seizure medicines may slightly increase the level of Zarontin in the blood, but the combination of these two medications is often beneficial.

The level of Zarontin in the blood is reduced if it is taken along with certain other seizure medicines, including:

• Tegretol, Carbatrol (carbamazepine)
• Dilantin, Phenytek (phenytoin)
• Mysoline (primidone)
• phenobarbital

The dosage of Zarontin may need to be increased if it is used with these other medicines.

Reviewed February 2004 by Barry Gidal, PharmD, epilepsy.com Editorial Board.