Dofetilide (Tikosyn) is used to correct irregular heartbeats (arrhythmias). It relaxes an overactive heart and helps improve the heart’s pumping action.

How and when should dofetilide be used?

The first dose of dofetilide is given in the hospital. This is so your condition and response the medication dose can be closely monitored and your doctor can determine the right dose for you.

Dofetilide comes in capsule form. Your prescription label tells you how much medication to take and how often to take it. It is important to take dofetilide exactly as prescribed, at the same time every day, even if you feel well. Ask your doctor or pharmacist to explain anything you don’t understand. You can take dofetilide with or without food. Do not skip a dose or take less or more of the medication than your doctor prescribes.

If you have any questions about your prescription or how to get refills, ask your pharmacist for help.

Where can I get my dofetilide prescription filled?

Not all pharmacies can fill your dofetilide prescription. Check with your regular pharmacy to see if they can order the medication. If you have trouble finding the medication, talk to your doctor.

What special instructions should I follow while using this drug?

Before dofetilide is prescribed, tell your doctor:

  • If you have ever had an allergic reaction to dofetilide and describe what happened when you took this medication.
  • The names of all prescription and nonprescription (over-the-counter) medications, vitamins, and herbal supplements you take.
  • Do not start taking any new medications or supplements without asking your doctor.
  • If you have heart problems, especially a heart condition called “long QT syndrome,” or if you have kidney or liver problems, or low potassium or magnesium levels.
  • If you are pregnant, plan to get pregnant or are breastfeeding.

Other important instructions when taking dofetilide:

  • Although dofetilide is used to correct an irregular heartbeat, taking this medication can also increase your risk for developing an irregular heartbeat. Because of this, it is important that you keep all of your doctor and laboratory appointments to check your response to the medication. You will likely need an occasional electrocardiogram (EKG) to check your heart rate and rhythm. You may also need blood tests to see if you need any changes to your medication.
  • Ask your pharmacist any questions you have about your medication. Read the information that comes with your prescription or this patient education handout every time you get your prescription refilled, especially if you have had recent changes in your medications or health.
  • DO NOT take dofetilide (and tell your doctor) if you take: verapamil (Calan, Isoptin, others), ketoconazole (Nizoral),  itraconazole (Sporanox), trimethoprim (Proloprim, Primsol, and others), trimethoprim with sulfamethoxazole (Bactrim,  Septra, ​Cotrimoxazole), hydrochlorothiazide, (Geodon), amitriptyline (Elavil) or other tricyclic antidepressants,  promethazine (Phenergan), prochlorperazine (Compazine), disopyramide (Norpace), or sotalol.
  • The following drugs can INTERACT with dofetilide. Check with your physician before you take any of the following  medications: amiodarone (Cordarone); digoxin (Lanoxin); metformin (Glucophage, Glucovance); megestrol (Megace);  diltiazem (Cardizem, others); quinine; fluconazole (Diflucan); erythromycin; clarithromycin (Biaxin); moxifloxacin (Avelox);  fluoxetine (Prozac), sertraline (Zoloft), paroxetine (Paxil) and other selective serotonin reuptake inhibitors; furosemide  (Lasix), amiloride (Midamor) and other diuretics; and protease inhibitors.
  • Before you have any surgical or dental procedure or emergency treatment, tell the doctor or dentist that you take dofetilide.

You may need to wear identification that says you are taking dofetilide

  • Never stop taking this medicine without first asking your doctor.
  • Follow your doctor’s advice on diet, including guidelines for alcoholic beverages.
  • Be sure you always have enough of this medication with you. Check your supply before vacations, holidays and other occasions you may not have access to an authorized pharmacy.

What should I do if I forget to take a dose?

Take the missed dose as soon as you remember. However, if you remember a missed dose near the time you should take the next dose, take only the regularly scheduled dose. Do not take a double dose. If you are unsure of what to do, contact your doctor or pharmacist.

What are the common side effects? What can I do about them?

Call your doctor right away or seek emergency treatment if you have:

  • Fast or irregular heartbeat
  • Pounding, slow heartbeat
  • Chest pain
  • Dizziness or lightheadedness/faint
  • Difficulty breathing
  • Severe diarrhea
  • Vomiting with loss of appetite
  • Unusual sweating
  • Increased thirst

Talk with your doctor if you have these less serious side effects:

  • Headache
  • Dizziness
  • Any other side effects that cause concern

How should I store dofetilide?

  • Store dofetilide in a tightly closed container at room temperature in a dry place. Keep this medicine away from direct light and heat.
  • Do not store dofetilide in the bathroom or other damp areas. Moisture can break down the medication.
  • Keep this and all other medications out of the reach of children.
  • Never share your medication with anyone.
  • Never take outdated medications. Some medication prescription labels list an expiration date. If such a date is not on your medication label, or if you are unsure how old a medication is, call your pharmacy. 

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