Dofetilide

Dofetilide is a medication for heart rhythm issues, known as an antiarrhythmic.

Dofetilide helps keep the heart beating normally in people with specific heart rhythm disorders in the atrium (the upper chambers of the heart that let blood flow into the heart). Dofetilide is used in individuals with atrial fibrillation or atrial flutter.

Dofetilide may also be used for reasons not mentioned in this medication guide.

Dofetilide is available only from a hospital or specialty pharmacy.

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 medicine causes serious side effects.

Follow all directions on your prescription label. Do not take this medicine in larger or smaller amounts or for longer than recommended.

You may take dofetilide with or without food.

You should not skip doses or stop using dofetilide suddenly. Stopping suddenly may make your condition worse. Follow your doctor's instructions about tapering your dose.

Tell your doctor if you have a prolonged illness that causes severe diarrhea, vomiting, or heavy sweating. These conditions can cause an electrolyte imbalance, making it dangerous for you to use dofetilide.

Your blood pressure will need to be checked often. Your kidney function may also need to be checked with frequent blood tests.

Store at room temperature away from moisture and heat.

You should not take dofetilide if you have severe kidney disease or a history of Long QT syndrome.

Serious drug interactions can happen when certain medicines are taken together with dofetilide. Inform each of your healthcare providers about all medicines you are currently using, and any medicine you begin or stop using.

You will need to stay in a hospital for at least 3 days when you first start taking dofetilide. This is to monitor your heart rhythm and kidney function in case the medicine causes serious side effects.

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

• severe kidney disease (or if you are on dialysis); or
• a history of Long QT syndrome.

Some medicines can cause unwanted or dangerous effects when used with dofetilide and should not be taken at the same time. Your doctor may need to change your treatment plan if you use any of the following drugs:

• cimetidine;
• dolutegravir;
• ketoconazole;
• megestrol;
• prochlorperazine;
• trimethoprim (Proloprim, Trimpex, Bactrim, Septra);
• verapamil; or
• a diuretic (water pill) that contains hydrochlorothiazide (HCTZ), such as Accuretic, Aldactazide, Atacand HCT, Benicar HCT, Diovan HCT, Dyazide, Exforge HCT, Hyzaar, Lopressor HCT, Maxzide, Micardis HCT, Monopril HCT, Prinzide, Tekturna HCT, Vaseretic, and others.

To make sure dofetilide is safe for you, tell your doctor if you have:

• heart disease, high blood pressure;
• liver or kidney disease;
• depression, mental illness;
• asthma or allergies;
• any active infection;
• skin problems; or
• an electrolyte imbalance (such as low levels of potassium or magnesium in your blood).

It is not known if dofetilide will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant while using this medicine.

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

Get emergency medical help if you notice any of these signs of an allergic reaction: hives; trouble breathing; swelling of your face, lips, tongue, or throat.

Dofetilide may cause serious side effects. Call your doctor right away if you experience:

• headache along with chest pain and severe dizziness, fainting, fast or pounding heartbeats;
• loss of appetite, vomiting, or severe diarrhea; or
• low magnesium or potassium—confusion, irregular heart rate, increased thirst or urination, sweating, involuntary muscle movements, leg pain, muscle weakness, or feeling weak.

Common side effects of dofetilide may include:

• mild headache;
• mild dizziness; or
• cold-like symptoms such as stuffy nose, sneezing, or sore throat.

This is not a complete list of side effects, and others may happen. Call your doctor for medical advice about side effects. You can report side effects to the FDA at 1-800-FDA-1088.

Skip the missed dose and take your next dose at the usual time to stay on schedule. Do not take extra medicine to make up for the missed dose.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Grapefruit and grapefruit juice may interact with dofetilide and cause unwanted side effects. Talk to your doctor about using grapefruit products.

Other drugs may interact with dofetilide, including prescription and over-the-counter medicines, vitamins, and herbal products. Inform each of your health care providers about all medicines you are currently using and any medicine you begin or stop using.