Generic Name: dofetilide, Oral capsule

Generic Name:

dofetilide, Oral capsule

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SECTION 1 of 5

Highlights for dofetilide

Oral capsule
1

Dofetilide is an oral drug used to treat or prevent a type of irregular heart rate called atrial fibrillation and atrial flutter.

2

Your doctor will decide your dose of dofetilide. It’ll be calculated based on your kidney function and heart rate.

3

Common side effects include headache, chest pain, and dizziness.

4

If you’re starting, restarting, or increasing your dose of dofetilide, you’ll be monitored for at least 3 days in a hospital. This is done to check your kidney function and to monitor your heart rate and heart function continuously. Your heart rate will have to be normal for more than 12 hours before you can go home.

5

Dofetilide can cause serious side effects, including a type of irregular heart rate called Torsades de Pointes that could lead to death. Your risk may be higher if you have low potassium levels or if you take other drugs that affect the heart.

IMPORTANT INFORMATION

FDA Warning

This drug has a Black Box Warning. This is the most serious warning from the Food and Drug Administration (FDA). A black box warning alerts doctors and patients to potentially dangerous effects.

Risk for starting, restarting, or increasing your dose: If you’re starting, restarting, or increasing your dose of dofetilide, you’ll be monitored in the hospital for at least 3 days. This is done to check your kidney function and to monitor your heart rate and heart function continuously.

Irregular heart rate warning

Dofetilide can cause serious side effects, including a type of irregular heart rate called Torsades de Pointes. This can be fatal. Your risk may be increased if you have high blood levels of dofetilide. This is most likely to occur within the first 3 days of starting or increasing your dose of the drug.

People with the irregular heart rate long QT syndrome shouldn’t take this drug. Dofetilide can make your irregular heart rate worse.

Severe kidney problems warning

Kidney problems can increase blood levels of the drug in your body and increase your risk of serious side effects such as a dangerous irregular heartbeat. Some people with kidney problems can’t take this drug. Your doctor will decide whether you can take this drug or if the dose needs to be decreased.

Low potassium levels warning

This drug may cause changes in your heart rhythm. Low potassium blood levels may increase your risk of irregular heartbeat while taking this drug. To prevent this, your doctor will check your potassium blood levels before you start taking this drug. Potassium blood levels must be normal before starting treatment.

Drug Features

Dofetilide is a prescription drug. It’s available as an oral capsule.

Why It's Used

Dofetilide is used to treat irregular heart rate in atrial fibrillation and atrial flutter. This drug makes your heart rate normal (normal sinus rhythm).

How It Works

Dofetilide belongs to a class of drugs called antiarrhythmics.

More Details

How It Works

Dofetilide belongs to a class of drugs called antiarrhythmics. A class of drugs refers to medications that work similarly. They have a similar chemical structure and are often used to treat similar conditions.

Dofetilide is a Class III antiarrhythmic. It blocks heart potassium channels to help prevent and treat irregular heart rate.

SECTION 2 of 5

dofetilide Side Effects

Oral capsule

Most Common Side Effects

The most common side effects that occur with dofetilide include:

  • headache

  • chest pain

  • dizziness

If these effects are mild, they may go away within a few days or a couple of weeks. If they’re more severe or don’t go away, talk to your doctor or pharmacist.

Serious Side Effects

If you experience any of these serious side effects, call your doctor right away. If your symptoms are potentially life threatening, or if you think you’re experiencing a medical emergency, call 9-1-1.

  • fast heart rate. This may be a sign that dofetilide isn’t working.

  • irregular heart rate. Symptoms may include palpitations (or abnormal heartbeat), dizziness, and fainting. Irregular heart rate may be a sign of Torsades de Pointes. This condition could be fatal.

  • severe diarrhea or diarrhea that lasts several days

  • vomiting

  • loss of appetite

  • changes in how thirsty you feel, such as drinking more than normal or not wanting to drink fluids at all

Pharmacist's Advice
Healthline Pharmacist Editorial Team

Dofetilide doesn’t cause drowsiness.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we cannot guarantee that this information includes all possible side effects. This information is not a substitute for medical advice. Always discuss possible side effects with a healthcare provider who knows your medical history.
SECTION 3 of 5

dofetilide May Interact with Other Medications

Oral capsule

Dofetilide can interact with other medications, herbs, or vitamins you might be taking. That’s why your doctor should manage all of your medications carefully. If you’re curious about how this drug might interact with something else you’re taking, talk to your doctor or pharmacist.

Note: You can reduce your chances of drug interactions by having all of your prescriptions filled at the same pharmacy. That way, a pharmacist can check for possible drug interactions.

Food Interactions

Avoid grapefruit juice while taking this medication because grapefruit juice can increase the amount of dofetilide in your body.

Medications that Might Interact with This Drug

Medicines for heartburn or stomach or intestinal ulcers
  • cimetidine

This medication shouldn’t be taken with dofetilide. It can increase the amount of dofetilide in your body a lot. Higher blood levels of dofetilide can cause the irregular heart rate called Torsades de Pointes. This can be fatal.

Medicines for high blood pressure
  • Water pills that remove potassium, such as:
    • hydrochlorothiazide or hydrochlorothiazide with triamterene
  • Calcium channel blockers, such as:
    • verapamil
    • bepridil

These medications shouldn’t be taken with dofetilide. They can increase the amount of dofetilide in your body and decrease potassium levels. This may cause irregular heartbeat. Higher blood levels of dofetilide can cause the irregular heart rate called Torsades de Pointes. This can be fatal.

Medicine for fungal infections
  • ketoconazole

This drug shouldn’t be taken with dofetilide. It can increase the amount of dofetilide in your body a lot. Higher blood levels of dofetilide can cause the irregular heart rate called Torsades de Pointes. This can be fatal.

Medicines for bacterial infections
  • trimethoprim
  • sulfamethoxazole
  • macrolides
  • fluoroquinolones

These medications shouldn’t be taken with dofetilide. Some of these drugs may lengthen the QT interval on an ECG (the time it takes for your heart to contract and then refill with blood before beginning the next contraction). This may increase your chance of irregular heartbeat.

Medicine for nausea
  • prochlorperazine

This drug shouldn’t be taken with dofetilide. It can increase the amount of dofetilide in your body a lot. Higher blood levels of dofetilide can cause the irregular heart rate called Torsades de Pointes. This can be fatal.

Medicine for breast cancer
  • megestrol

This drug shouldn’t be taken with dofetilide. It can increase the amount of dofetilide in your body a lot. Higher blood levels of dofetilide can cause the irregular heart rate called Torsades de Pointes. This can be fatal.

Medicine for human immunodeficiency virus (HIV)
  • dolutegravir

This drug shouldn’t be taken with dofetilide. It can increase the amount of dofetilide in your body a lot. Higher blood levels of dofetilide can cause the irregular heart rate called Torsades de Pointes. This can be fatal.

Medicines for depression and mood disorders
  • tricyclic antidepressants, such as:
    • amitriptyline (Elavil)
    • amoxapine (Asendin)
    • clomipramine (Anafranil)
    • desipramine (Norpramin)
    • doxepin (Sinequan)
    • imipramine (Tofranil)
    • maprotiline (Ludiomil)
    • nortriptyline (Pamelor)
    • protriptyline (Vivactil)
    • trimipramine (Surmontil)
  • phenothiazines
    • chlorpromazine
    • prochlorperazine
    • thioridazine

Medicines to treat irregular heart rates (arrhythmias)
  • Class I or Class III antiarrhythmics

These drugs shouldn’t be used right before you take dofetilide. Depending on which drug you were taking, you may need to wait a few days or weeks before you start dofetilide.

  • amiodarone

These drugs can’t be in your body at the same time. Amiodarone can stay in your body for a very long time. Before you can take dofetilide, amiodarone blood levels have to be below 0.3 mg/L.  Or amiodarone has to be stopped for at least three months before dofetilide is started.

Medicines for diabetes
  • metformin

This medicine may increase the levels of dofetilide in your body. Your doctor may monitor you extra closely if you take these drugs together.

Sometimes, you may need to take medicines that interact with dofetilide. In these cases, you may need to stop taking dofetilide temporarily. You may need to stop taking dofetilide at least 2 days before you start taking the other medication. 

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs interact differently in each person, we cannot guarantee that this information includes all possible interactions. This information is not a substitute for medical advice. Always speak with your healthcare provider about possible interactions with all prescription drugs, vitamins, herbs and supplements, and over-the-counter drugs that you are taking.

People with low potassium levels

Low potassium blood levels can increase the chance that you’ll experience a dangerous irregular heartbeat while taking this drug. To prevent this, your doctor will check your potassium blood levels before you start taking this drug. Potassium blood levels must be normal before starting treatment.

People with kidney problems

The kidneys process this drug. If your kidneys don’t work well, they may not be able to clear dofetilide from your body. This can cause toxic levels of the drug to build up in your body. If you have severe kidney problems, don’t take dofetilide. If you have mild kidney problems, your doctor may start you on a lower dose.

People with heart problems

If you have the heart condition QT prolongation, don’t take dofetilide. This medication can worsen this heart condition and cause you to have a dangerous irregular heartbeat.

Pregnant women

Dofetilide is a category C pregnancy drug. That means two things:

  1. Research in animals has shown adverse effects to the fetus when the mother takes the drug.
  2. There haven’t been enough studies done in humans to be certain how the drug might affect the fetus.

Tell your doctor if you’re pregnant or plan to become pregnant. Dofetilide should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Women who are nursing

It isn’t known if dofetilide passes through breast milk. If it does, it may cause serious effects in a breastfeeding child. 

You and your doctor may need to decide if you’ll take dofetilide or breastfeed.

For Seniors

As you age, your organs, such as your liver and kidneys, don’t work as well as they once did. This drug is cleared from your body by the kidneys. If you have reduced kidney function, the drug could build up in your body and cause serious side effects. Your starting dose of dofetilide may be lower. If you have severe kidney problems you might not be able to take this medication.

For Children

The safety and effectiveness of dofetilide in people under 18 years old haven’t been established.

Allergies

Don’t take this drug again if you’ve ever had an allergic reaction to it. Taking it again could be fatal.

SECTION 4 of 5

How to Take dofetilide (Dosage)

Oral capsule

All possible dosages and forms may not be included here. Your dose, form, and how often you take it will depend on: 

  • your age
  • the condition being treated
  • how severe your condition is
  • other medical conditions you have
  • how you react to the first dose

What Are You Taking This Medication For?

Atrial fibrillation and atrial flutter
Form: Oral capsule
Strengths: 125 mcg (0.125 mg), 250 mcg (0.25 mg), and 500 mcg (0.5 mg)
Adult Dosage (ages 18-64 years)
  • Before you start dofetilide your doctor will make sure that:
    • your potassium blood level is not low
    • you’re taking a blood thinner if you have atrial fibrillation
  • Your doctor will calculate your dose of dofetilide. It’s based on your kidney function and heart rate.
  • The usual dose of dofetilide is 500 mcg taken twice a day. Your starting dose may be lower depending on your kidney function and heart rate.
  • Your dose will be adjusted based on how your heart reacts to dofetilide. Your doctor will do heart tests called electrocardiograms. Based on those results, they’ll adjust your dose if needed.
Child Dosage (ages 0-17 years)

The safety and effectiveness of dofetilide haven’t been established in people younger than 18 years old.

Senior Dosage (ages 65 years and older)

Your dose will be based on your kidney function. As you age, your organs, such as your liver and kidneys, don’t work as well as they once did. Your starting dose may be lower.

Special Considerations

Poor kidney function: If you have kidney problems, your body won’t be able to clear this drug as well. This may cause the drug to build up in your body and cause more side effects. Your doctor may start you at a lower dose. If your kidney function gets worse, your doctor may stop your medication.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we cannot guarantee that this list includes all possible dosages. This information is not a substitute for medical advice. Always to speak with your doctor or pharmacist about dosages that are right for you.
Pharmacist's Advice
Healthline Pharmacist Editorial Team

Dofetilide comes with serious risks if you don’t take it as prescribed.

If You Don’t Take It at All

Your irregular heart rate may get worse. This condition can be fatal.

If You Take Too Much

Taking too much of this drug can increase the chance that you'll have a dangerous, life-threatening irregular heartbeat.

If You Stop Taking It Suddenly

Your irregular heart rate may get worse. This condition can be fatal.

If You Don’t Take It on Schedule

Your irregular heart rate may get worse. This condition can be fatal. Taking more dofetilide than your doctor prescribed can cause higher levels of dofetilide in your blood. This can cause the irregular heart rate Torsades de Pointes. This condition can be fatal.

What to Do If You Miss a Dose

If you forget to take your dose, just take your next dose at its regular scheduled time.

Don’t try to make up for a missed dose by taking two doses at once. Taking more dofetilide than your doctor prescribed can cause higher levels of dofetilide in your blood. This can cause the irregular heart rate Torsades de Pointes. This condition can be fatal.

How to Tell If the Drug Is Working

You may be able to tell if this drug is working if your heart rate returns to normal. Your doctor will monitor your heart rate and heart function.

Dofetilide is a long-term drug treatment.

Important Considerations for Taking Dofetilide
can be taken with or without food Dofetilide can be taken with or without food
Do not crush capsules Do not crush, cut, or chew the capsules. Swallow them whole
storage Store dofetilide at room temperature See Details
refillable Prescription is refillable
luggage Travel See Details
clinical monitoring Clinical Monitoring See Details
diet Your Diet See Details
not usually stocked Not every pharmacy stocks this drug, so call ahead
prior authorization needed Insurance See Details

Store dofetilide at room temperature

Keep it in temperatures from 59–86°F (15–30°C).

Keep the drug away from light and high temperature.

Keep your drugs away from areas where they could get wet, such as bathrooms. Store this drug away from moisture and damp locations.

Store dofetilide in a tightly closed container.

Keep dofetilide and all medicines out of reach of children.

Travel

When traveling with your medication:

  • Always carry your medication with you or in your carry-on bag.
  • Don’t worry about airport X-ray machines. They can’t hurt this medication.
  • You may need to show your pharmacy’s label to clearly identify the medication. Keep the original prescription label with you when traveling.
  • Be sure that you have enough medicine before you leave on your trip. It may be difficult to get this medication when you are traveling since many pharmacies don’t have it in stock.
  • Don’t leave this medicine in the car. Avoid keeping it in hot or freezing temperatures.

Clinical Monitoring

During treatment, your doctor will do the following tests to make sure that you’re getting the right dose of dofetilide and that the medication is working:

  • kidney function. This will be checked at least every 3 months.
  • heart rate and function. Your doctor will do a test called an electrocardiogram at least every 3 months.
  • blood levels of potassium and magnesium

Your Diet

Avoid drinking grapefruit juice while on this medication. Grapefruit juice can increase the amount of dofetilide in your body.

Insurance

Many insurance companies will require a prior authorization before they approve the prescription and pay for dofetilide.

Are There Any Alternatives?

There are other drugs available to treat your condition. Some may be more suitable for you than others. Talk to your doctor about possible alternatives.

What does the pill look like?

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SECTION 5 of 5

How Much Does dofetilide Cost?

Oral capsule
We've partnered with GoodRX so you can compare prices and save money on your next prescription. Check out the lowest cash prices below and enter your zip code to find the best deal near you.

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Lowest price for dofetilide

Membership warehouse $341.77
Publix $343.08
Kroger Pharmacy $343.09
These represent the lowest cash prices for dofetilide and may be lower than your insurance.

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Content developed in collaboration with University of Illinois-Chicago, Drug Information Group

Medically reviewed by Creighton University, Center for Drug Information and Evidence-Based Practice on June 30, 2015

Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up-to-date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or other healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.

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