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phenytoin oral


This information is generalized and not intended as specific medical advice. Consult your healthcare professional before taking or discontinuing any drug or commencing any course of treatment.

Medical warning:

Moderate. These medicines may cause some risk when taken together. Contact your healthcare professional (e.g. doctor or pharmacist) for more information.

How the interaction occurs:

When these two medicines are taken together, your body may process your seizure medicine more slowly, and your heart medicine more quickly.

What might happen:

The blood levels of your seizure medicine may increase and cause toxic effects. The blood levels of your heart medicine may decrease and cause a loss of effectiveness.

What you should do about this interaction:

If you experience nausea, vomiting, confusion, dizziness, or irregular heartbeat, contact your doctor. Your doctor may want to monitor your blood levels of medicine more regularly and adjust the dosages.Your healthcare professionals (e.g. doctor or pharmacist) may already be aware of this drug interaction and may be monitoring you for it. Do not start, stop, or change the dosage of any medicine before checking with them first.


1.Gore JM, Haffajee CI, Alpert JS. Interaction of amiodarone and diphenylhydantoin. Am J Cardiol 1984 Nov 1;54(8):1145.
2.Lalloz MR, Byfield PG, Greenwood RM, Himsworth RL. Binding of amiodarone by serum proteins and the effects of drugs, hormones and other interacting ligands. J Pharm Pharmacol 1984 Jun;36(6):366-72.
3.McGovern B, Geer VR, LaRaia PJ, Garan H, Ruskin JN. Possible interaction between amiodarone and phenytoin. Ann Intern Med 1984 Nov;101(5):650-1.
4.Shackleford EJ, Watson FT. Amiodarone--phenytoin interaction. Drug Intell Clin Pharm 1987 Nov;21(11):921.
5.Nolan PE Jr, Marcus FI, Hoyer GL, Bliss M, Gear K. Pharmacokinetic interaction between intravenous phenytoin and amiodarone in healthy volunteers. Clin Pharmacol Ther 1989 Jul;46(1):43-50.
6.Nolan PE Jr, Erstad BL, Hoyer GL, Bliss M, Gear K, Marcus FI. Steady-state interaction between amiodarone and phenytoin in normal subjects. Am J Cardiol 1990 May 15;65(18):1252-7.
7.Nolan PE Jr, Marcus FI, Karol MD, Hoyer GL, Gear K. Effect of phenytoin on the clinical pharmacokinetics of amiodarone. J Clin Pharmacol 1990 Dec; 30(12):1112-9.
8.Ahmad S. Amiodarone and phenytoin: interaction. J Am Geriatr Soc 1995 Dec; 43(12):1449-50.

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