Dofetilide: uses, dosing, side effects & brands
Dofetilide is an antiarrhythmic sold in the U.S. under one brand, for atrial fibrillation and atrial flutter. Below: what the FDA label says, every product that contains it, what the pills look like, and its recall record.
Key facts
- Drug class
- Antiarrhythmic
- Treats
- Atrial Fibrillation and Atrial Flutter
- Available as
- Capsule
- Sold as
- Tikosyn
- Prescription?
- Prescription only
- Generic available?
- Not in our catalog
- What the pharmacy pays
- about $6 for a 30-count supply — not your price
- Boxed warning
- Boxed warning
How dofetilide is dosed
From the FDA label for Tikosyn (application NDA020931). Other dofetilide products — different forms, different strengths — are dosed differently. Follow the label for the one you were prescribed.
Therapy with TIKOSYN must be initiated (and, if necessary, re-initiated) in a setting that provides continuous electrocardiographic (ECG) monitoring and in the presence of personnel trained in the management of serious ventricular arrhythmias. Patients should continue to be monitored in this way for a minimum of three days. Additionally, patients should not be discharged within 12 hours of electrical or pharmacological conversion to normal sinus rhythm. • The dose of TIKOSYN must be individualized according to calculated creatinine clearance and QTc. (QT interval should be used if the heart rate is <60 beats per minute. There are no data on use of TIKOSYN when the heart rate is <50 beats per minute.) The usual recommended dose of TIKOSYN is 500 mcg BID, as modified by the dosing algorithm described below. For consideration of a lower dose, see Special Considerations below. • Serum potassium should be maintained within the normal range before TIKOSYN treatment is initiated and should be maintained within the normal range while the patient remains on TIKOSYN therapy. (See WARNINGS, Hypokalemia and Potassium-Depleting Diuretics ). In clinical trials, potassium levels were generally maintained above 3.6–4.0 mEq/L. • Patients with atrial fibrillation should be anticoagulated according to usual medical practice prior to electrical or pharmacological cardioversion. Anticoagulant…
Dofetilide side effects
The TIKOSYN clinical program involved approximately 8,600 patients in 130 clinical studies of normal volunteers and patients with supraventricular and ventricular arrhythmias. TIKOSYN was administered to 5,194 patients, including two large, placebo-controlled mortality trials (DIAMOND CHF and DIAMOND MI) in which 1,511 patients received TIKOSYN for up to three years. In the following section, adverse reaction data for cardiac arrhythmias and non-cardiac adverse reactions are presented separately for patients included in the supraventricular arrhythmia development program and for patients included in the DIAMOND CHF and MI mortality trials (see CLINICAL STUDIES, Safety in Patients with Structural Heart Disease, DIAMOND Studies , for a description of these trials). In studies of patients with supraventricular arrhythmias, a total of 1,346 and 677 patients were exposed to TIKOSYN and placebo for 551 and 207 patient years, respectively. A total of 8.7% of patients in the dofetilide groups were discontinued from clinical trials due to adverse events compared to 8.0% in the placebo groups. The most frequent reason for discontinuation (>1%) was ventricular tachycardia (2.0% on dofetilide vs. 1.3% on placebo). The most frequent adverse events were headache, chest pain, and dizziness. Serious Arrhythmias and Conduction Disturbances: Torsade de Pointes is the only arrhythmia that showed…
Who shouldn’t take dofetilide
TIKOSYN is contraindicated in patients with congenital or acquired long QT syndromes. TIKOSYN should not be used in patients with a baseline QT interval or QTc >440 msec (500 msec in patients with ventricular conduction abnormalities). TIKOSYN is also contraindicated in patients with severe renal impairment (calculated creatinine clearance <20 mL/min). The concomitant use of verapamil or the cation transport system inhibitors cimetidine, trimethoprim (alone or in combination with sulfamethoxazole), or ketoconazole with TIKOSYN is contraindicated (see WARNINGS and PRECAUTIONS, Drug-Drug Interactions ), as each of these drugs cause a substantial increase in dofetilide plasma concentrations. In addition, other known inhibitors of the renal cation transport system such as prochlorperazine, dolutegravir and megestrol should not be used in patients on TIKOSYN. The concomitant use of hydrochlorothiazide (alone or in combinations such as with triamterene) with TIKOSYN is contraindicated (see PRECAUTIONS, Drug-Drug Interactions ) because this has been shown to significantly increase dofetilide plasma concentrations and QT interval prolongation. TIKOSYN is also contraindicated in patients with a known hypersensitivity to the drug.
Every dofetilide product we track (1)
Same active ingredient — different manufacturer, form, price and FDA recall record. That last one is what our independent score measures.
Only one: Tikosyn.
What dofetilide pills look like
Imprint codes, colour and shape from the FDA’s labelling data. Match the imprint on your pill — or search any imprint.
| Imprint | Strength | Colour | Shape | Maker |
|---|---|---|---|---|
| G125;024 | 0.125 mg | orange, white | capsule | — |
| G250;025 | 0.25 mg | pink | capsule | — |
| G500;026 | 0.5 mg | white, pink | capsule | — |
| ML;125 | 0.125 mg | white, brown | capsule | — |
| ML;250 | 0.25 mg | orange | capsule | — |
| ML;500 | 0.5 mg | white, orange | capsule | — |
| MD;2 | 0.25 mg | pink | capsule | — |
| TKN;125;PFIZER | 0.125 mg | orange, white | capsule | — |
| TKN;250;PFIZER | 0.25 mg | pink | capsule | — |
| TKN;500;PFIZER | 0.5 mg | pink, white | capsule | — |
| HC1 | 0.125 mg | orange, white | capsule | — |
| HC2 | 0.25 mg | pink | capsule | — |
How long dofetilide keeps
No dofetilide label we read sets a separate limit for after opening, but they do specify how it must be stored — and the stability behind any date assumes those conditions.
What people report to the FDA about dofetilide
The FDA Adverse Event Reporting System (FAERS) collects reports from patients and clinicians. It holds 2,898 reports naming dofetilide, and the FDA flagged 65% of those reports as serious. The effects reported most often — leaving out reports about overdose, misuse or the condition being treated, which dominate the raw list for common medicines:
- atrial fibrillation254 reports
- electrocardiogram qt prolonged186 reports
- dyspnoea163 reports
- dizziness132 reports
- fatigue126 reports
- headache100 reports
- diarrhoea95 reports
- torsade de pointes93 reports
Read these as a signal, not a rate. A report does not mean dofetilide caused the effect — anyone can file one, and many describe people taking several medicines for several conditions. Crucially there is no denominator: FAERS does not record how many people took the drug, so these counts cannot be turned into “X% of patients” — a bigger number often just means a more widely used or more talked-about drug. Duplicates exist, and publicity drives reporting. For what is actually established, read the FDA label.
Source: openFDA drug/event (FAERS), retrieved September 25, 2026.
Related calculators
Frequently asked questions
What is dofetilide?
Tikosyn (Dofetilide) is an antiarrhythmic used to treat Atrial Fibrillation, Atrial Flutter.
What kind of drug is dofetilide?
The FDA classifies dofetilide as an antiarrhythmic. Antiarrhythmics steady an irregular heartbeat by controlling the flow of sodium, potassium, or calcium ions through heart-cell channels (or blunting adrenaline's effect), which slows or normalizes the heart's electrical signals so it beats in a more regular rhythm. If you are checking whether it is safe to combine with something else, the class is what matters — two drugs from the same class usually should not be stacked.
Can you take dofetilide with other medicines?
It depends on the medicine. We check it against the FDA labels rather than guessing: our interaction checker searches each drug's own label for the other and quotes what it says, naming the section it came from. Run dofetilide against whatever else you take — and remember that a label not naming a drug is not the same as that combination being safe.
What forms does dofetilide come in?
Across the brands we track, dofetilide is currently marketed as capsule, per the FDA's National Drug Code Directory. Each form is dosed differently — follow the label for the exact product you were prescribed.
Is there a generic dofetilide?
We do not currently list a generic-labelled dofetilide product. That does not always mean none exists — it means none appears under a generic name in the FDA data we track. Ask your pharmacist.
Cite this page
- APA
- pharmaranks. (2026, July 24). Dofetilide: uses, dosing, side effects & brands. https://pharmaranks.com/drugs/dofetilide
- MLA
- “Dofetilide: uses, dosing, side effects & brands.” pharmaranks, 24 July 2026, https://pharmaranks.com/drugs/dofetilide.
We summarise public FDA and NIH sources — for a clinical claim, cite the primary source we link to as well.
Sources: FDA openFDA drug label, National Drug Code Directory, and Enforcement (recall) database. This page reproduces public FDA data and is not medical advice. Dosing is set by your prescriber.
Read the full FDA label for dofetilide on DailyMed (NIH) ↗ — including its boxed warning in full.