Warnings

Dofetilide

Medically Reviewed by Dr. Harshi Dhingra, M.D.

Last Reviewed: Mar 20, 2025

Warnings

Dofetilide (Tikosyn) Risks, Warnings, and Complications

Dofetilide can cause or worsen health problems in some people. Talk with your doctor about other treatment options for an irregular heartbeat if you are at a high risk of complications from this medication. Some of the risks of dofetilide use include:

VENTRICULAR CONDUCTION ABNORMALITIES: Treatment with dofetilide can cause serious ventricular arrhythmias, mainly a polymorphic ventricular tachycardia with QT interval prolongation called Torsade de Pointes (TdP). TdP can progress into ventricular fibrillation and cause sudden cardiac death. The risk of TdP is directly related to dofetilide plasma concentrations (blood levels of the drug). Other risk factors include reduced creatinine clearance and interactions between dofetilide and certain other drugs that can increase dofetilide plasma concentration.
Your doctor will adjust your dose of dofetilide based on blood concentration while you are in the hospital at the time of starting treatment, to lower the risk of TdP. They will monitor creatinine clearance and ECG to check for QT interval prolongation.
Clinical trials have shown that:
QT interval increases in direct proportion to the dofetilide dose.
The frequency of Torsade de Pointes is reduced when patients are dosed based on creatinine clearance (renal function).
The majority of TdP episodes occur in the first 3 days of dofetilide therapy.
Two large placebo-controlled studies in patients with congestive heart failure or structural heart disease (DIAMOND CHF/MI) have shown that mortality rates are not higher in dofetilide-treated patients compared to placebo.
DRUG INTERACTIONS: Certain dofetilide drug interactions can increase the risk of potentially life-threatening heart rhythm abnormalities.
As noted, there is a direct relationship between the drug levels of dofetilide in the body and QT interval prolongation and Torsade de Pointes, a serious heart rhythm abnormality. The use of other drugs that interfere with dofetilide metabolism or renal elimination can potentially increase dofetilide levels and, consequently, the risk of Torsade de Pointes. Some of the drugs that can increase systemic dofetilide exposure include the GERD medicine cimetidine, the antibiotic trimethoprim, and the antifungal drug ketoconazole. The use of these medications is contraindicated with dofetilide.
Other drugs that cause QT interval prolongation should not be used with dofetilide. Examples include cisapride for GERD, bepridil for angina, phenothiazines (antipsychotics), tricyclic antidepressants, and certain antibiotics (some fluoroquinolones and oral macrolides). In addition, class I or class III antiarrhythmic agents need to be stopped before starting dofetilide.
HYPOKALEMIA: Hypokalemia (low potassium) or hypomagnesemia (low magnesium) can occur in patients taking diuretics (water pills) that are potassium-depleting. Low potassium can result in an increased risk of Torsade de Pointes and sudden death. Your healthcare provider will check potassium levels before starting and during treatment with dofetilide.

Precautions Before Starting Dofetilide (Tikosyn)

Tell your doctor if you have ever had allergic reactions to dofetilide, any of the active or inactive ingredients in dofetilide capsules, other antiarrhythmic drugs, or any other medications. Your pharmacy can give you a list of ingredients.

Give your doctor and pharmacist a complete list of your medications, including prescription drugs, over-the-counter medicines, dietary supplements, and herbal products. This can help prevent possible interactions between dofetilide and your other medicines.

Give your doctor a complete medical history. Dofetilide may not be safe for people with certain medical conditions, such as long QT syndrome, severe renal impairment (kidney disease), low potassium, structural heart disease, congestive heart failure, liver disease, or illnesses that cause severe diarrhea, vomiting, loss of appetite, sweating, or decreased thirst.

Talk to your healthcare provider about eating grapefruit or drinking grapefruit juice while on Tikosyn (dofetilide).

Tell your doctor if you are pregnant, could be pregnant, are planning a pregnancy, or are breastfeeding.

Precautions During Use of Dofetilide (Tikosyn)

Keep all your medical and laboratory appointments during treatment with dofetilide. Your doctor may want to adjust your dose. They will also order laboratory tests to check kidney function and potassium levels as well as check your heart rhythm regularly to monitor your response to the drug.

Tell all your healthcare professionals you are taking dofetilide, especially before surgical procedures, including dental treatment.

Tell your doctor if you become pregnant while on this medicine.

Dofetilide (Tikosyn) Drug Interactions

Taking dofetilide with certain other drugs can affect how it works. Possible drug interactions between dofetilide and your other medications can increase the risk of serious adverse reactions. Your doctor may change the dose of your medications, switch you to a different medication, and/or monitor you carefully for serious side effects if there are known interactions between dofetilide and your other medicines. Dofetilide can have interactions with the following medications:

GERD medicine - cimetidine (Tagamet)
HIV medicine - dolutegravir (Tivicay)
Antifungal agent - ketoconazole (Nizoral)
Diuretics (water pills) - hydrochlorothiazide (Oretic, Microzide) and hydrochlorothiazide and triamterene (Maxzide, Dyazide)
Progestin hormone - megestrol (Megace)
Nausea and vomiting medicine - prochlorperazine (Compro, Procomp)
Antibiotic - trimethoprim (Primsol) and trimethoprim and sulfamethoxazole (Septra, Bactrim, Sulfatrim)
Calcium channel blocker for high blood pressure and angina - verapamil (Verelan, Calan, Covera)
Serotonin reuptake inhibitors
Protease inhibitors
Cannabis

The above list may not include all the possible interactions of dofetilide. Give your doctor or pharmacist a complete list of your medications, including prescription drugs, over-the-counter medicines, dietary supplements, and herbal remedies. Also, tell your healthcare provider if you smoke, drink alcohol, or use recreational drugs because some of these substances can cause serious health complications when used with prescription and over-the-counter medicines.

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