Dofetilide is a heart rhythm medication, also called an antiarrhythmic.

Dofetilide is used to help keep the heart beating normally in people with certain heart rhythm disorders of the atrium (the upper chambers of the heart that allow blood to flow into the heart). Dofetilide is used in people with atrial fibrillation or atrial flutter.

Dofetilide may also be used for purposes not listed in this medication guide.

Dofetilide is available only from a hospital or specialty pharmacy.

You should not take dofetilide if you are allergic to it, or if you have severe kidney disease (or you are on dialysis) or a history of Long QT syndrome.

Before you receive dofetilide, tell your doctor if you have heart disease, high blood pressure, kidney disease, severe liver disease, depression, mental illness, or an electrolyte imbalance (such as low levels of potassium or magnesium in your blood).

There are many other drugs that should not be used together with dofetilide. Tell your doctor about all other medicines you use.

You will need to spend at least 3 days in a hospital setting when you first start taking dofetilide. This is so your heart rhythm and kidney function can be monitored in case the medication causes serious side effects.

Tell your doctor if you have a prolonged illness that causes severe diarrhea, vomiting, heavy sweating, increased thirst, or loss of appetite. These conditions can cause an electrolyte imbalance (such as low potassium levels), making it dangerous for you to use dofetilide.

Your blood pressure will need to be checked often. Visit your doctor regularly.

You should not take dofetilide if you are allergic to it, or if you have

• severe kidney disease (or you are on dialysis); or

• a history of Long QT syndrome.

There are many other drugs that can cause serious or life threatening medical problems if you take them together with dofetilide. The following drugs should not be used while you are taking dofetilide:

• cimetidine (Tagamet);

• ketoconazole (Nizoral);

• megestrol (Megace);

• prochlorperazine (Compazine);

• trimethoprim (Proloprim, Trimpex, Bactrim, Cotrim, Septra);

• verapamil (Covera, Calan, Isoptin, Verelan); or

• a diuretic (water pill) that contains hydrochlorothiazide (HCTZ), such as Accuretic, Aldactazide, Aldoril, Amturnide, Atacand HCT, Avalide, Benicar HCT, Capozide, Diovan HCT, Dyazide, Exforge HCT, Hyzaar, Hydra-Zide, HydroDiuril, Inderide, Lopressor HCT, Lotensin HCT, Maxzide, Micardis HCT, Moduretic, Monopril HCT, Prinzide, Tekturna HCT, Teveten HCT, Tribenzor, Uniretic, Vaseretic, Zestoretic, Ziac, and others.

To make sure you can safely take dofetilide, tell your doctor if you have any of these other conditions:

• heart disease, high blood pressure;

• kidney disease;

• severe liver disease;

• depression, mental illness; or

• an electrolyte imbalance (such as low levels of potassium or magnesium in your blood).

FDA pregnancy category C. It is not known whether dofetilide will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant while using this medication.

It is not known whether dofetilide passes into breast milk or if it could harm a nursing baby. You should not breast-feed while you are using dofetilide.