Phenytoin (oral): What Other Drugs Will Affect Phenytoin

Content provided by Cerner Multum, Inc.

What other drugs will affect phenytoin?

Drugs that can increase phenytoin levels in your blood include:

• stomach acid reducers such as cimetidine (Tagamet), ranitidine (Zantac), famotidine (Pepcid), or nizatidine (Axid);
• certain sedatives (such as Librium or Valium) or antidepressants (such as Prozac);
• estrogen hormone replacement;
• chlorpromazine (Thorazine), prochlorperazine (Compazine), thioridazine (Mellaril) and other phenothiazines;
• disulfiram (Antabuse);
• methylphenidate (Ritalin, Concerta, Daytrana); and
• sulfa drugs such as Septra or Bactrim.

Drugs that can make phenytoin less effective in controlling seizures include:

• carbamazepine (Tegretol, Epitol, Carbatrol);
• sucralfate (Carafate); and
• molindone (Moban).

Other drugs that can interact with phenytoin include:

• valproic acid (Depakene) or divalproex sodium (Depakote);
• phenobarbital (Luminal, Solfoton);

• steroid medicines (prednisone and others);
• antidepressants such as amitriptyline (Elavil), clomipramine (Anafranil), imipramine (Janimine, Tofranil), paroxetine (Paxil), and others;
• antibiotics such as rifampin (Rimactane, Rifadin, Rifamate) or doxycycline (Doryx, Vibramycin, Adoxa, and others);
• digitoxin (digitalis, Lanoxin);
• furosemide (Lasix); and
• theophylline (Elixophyllin, Theo-Dur, Theo-Bid, Theolair, Uniphyl).

This list is not complete and there are many other medicines that can interact with phenytoin. Tell your doctor about all the prescription and over-the-counter medications you use. This includes vitamins, minerals, herbal products, and drugs prescribed by other doctors. Do not start using a new medication without telling your doctor. Keep a list with you of all the medicines you use and show this list to any doctor or other healthcare provider who treats you.

Last updated:	February 08, 2008