Names & Terms You Will Hear
Plain-language meanings for the terms your care team may use.
| Term | Meaning |
|---|---|
| Dofetilide | The generic name. This is the drug itself. |
| Tikosyn | The brand name from Pfizer. It is the same drug as dofetilide. Your plan or pharmacy may use either name. |
| Class III antiarrhythmic | The drug group. These drugs slow the heart's electrical reset. That helps return an irregular rhythm to normal. |
| IKr potassium channel blocker | How the drug acts. Dofetilide blocks one channel only. Too much block stretches the QT interval, so close checks are needed. |
| QT interval / QTc | A number on your EKG. It shows how long the heart takes to reset. Dofetilide makes it a little longer on purpose. Too long (over 500 ms) can set off a bad rhythm. |
| Tikosyn REMS | A safety program the FDA requires. Only trained doctors and pharmacies can fill dofetilide. It is a federal safety rule, not red tape. |
| Torsades de pointes | A bad rhythm dofetilide can set off if the dose is wrong. It is the main reason for close QTc checks and the 3-day hospital start. |
What Is Dofetilide (Tikosyn)?
- Dofetilide is a prescription heart-rhythm drug. It helps keep a normal rhythm in people with atrial fibrillation (AFib) or atrial flutter.
- It blocks one kind of potassium channel in heart cells, called the IKr channel. This makes each cell wait a bit longer before it can fire again. That stops the off-beat signals.
- The FDA approves it for two uses. It can convert long-standing AFib back to a normal rhythm. It can also keep that rhythm steady in people with very bothersome AFib.
- It must be started in the hospital on a heart monitor for at least three days. The FDA requires this — it is not just a hospital rule. Any early rhythm problem is caught in this window.
- It is one of the few rhythm drugs that is safe when the heart's main pump is weak. The DIAMOND-CHF trial found it did not raise the risk of death.
Why It Matters
- Dofetilide is one of the strongest rhythm drugs we have. When AFib still bothers you even with rate control, it can make you feel much better.
- Flecainide and propafenone are not safe when the heart is weak or has blocked arteries. Dofetilide is. That makes it a key choice when other drugs are off the table.
- It does carry real risks. The main one is a bad rhythm called torsades de pointes, which can be deadly. The 3-day hospital start is built to catch it, when help is right there.
- The dose is set by how well your kidneys work. If your kidneys slow down, the drug can build up. That is why we keep checking them — it is a must, not an option.
- A few common drugs must never be taken with dofetilide. These are cimetidine, ketoconazole, trimethoprim, verapamil, and hydrochlorothiazide. Any one of them can set off a bad rhythm. Always check with us before you start a new drug.
Treatment Options
Shown in English for your safety — this section is not automatically translated. Confirm with your doctor or call the office.
- You start it in the hospital on a heart monitor for at least 72 hours.
- Your first dose is set by your creatinine clearance (CrCl), a kidney number. The dose is 500 mcg twice a day for CrCl > 60. It is 250 mcg for CrCl 40-60. It is 125 mcg for CrCl 20-39. The drug is not used at all for CrCl < 20.
- We check an EKG 2-3 hours after each of your first five doses. If the QTc goes up more than 15% from the start, or above 500 ms, we lower the dose or stop the drug.
- Once your dose is steady and your QTc is fine, you go home. You keep taking the drug as long as it works.
- You will need EKGs and blood tests for life. The blood tests check your kidneys and your potassium and magnesium levels.
- You may need to come back to the hospital for monitoring if you start a new drug or your kidneys change. Only then is it safe to go back on dofetilide.
- If dofetilide stops working or is no longer safe, other options can help. These include catheter ablation, amiodarone, or rate control.
Risks, Benefits, and Alternatives
Shown in English for your safety — this section is not automatically translated. Confirm with your doctor or call the office.
Every choice has trade-offs. Use this table to start the shared decision conversation with your care team.
| Option | Risks | Benefits | Alternatives |
|---|---|---|---|
| Starting dofetilide in the hospital for AFib that bothers you | You stay in the hospital 3 days. The torsades risk during the start is about 1-3%. You must avoid certain drugs for life and keep up with lab tests. | Strong rhythm control. It is safe when the heart is weak (DIAMOND-CHF). It can give you your life back when other drugs have failed. About 60-70% of well-chosen patients still do well at 1 year. | Amiodarone works longer but can harm the thyroid, lungs, and liver. Ablation lasts longer but is a procedure. Rate control alone is fine if AFib does not bother you. |
| Catheter ablation (pulmonary vein isolation) | This is a procedure. Risks are small but real: bleeding, stroke, and harm to the food pipe. AFib often comes back, so you may need it done again. | It can stop AFib with no drug. When it works, the benefit lasts. The 2023 AHA guideline picks it first for paroxysmal AFib that bothers you. | Dofetilide needs no procedure, but you take a daily drug and get checks. Amiodarone is less invasive but can harm organs over time. |
| Amiodarone | Over time it can harm the lungs, liver, thyroid, eyes, and skin. You need blood tests twice a year and a chest X-ray every 1-2 years. | It is the strongest rhythm drug. You can start it as an outpatient. It helps when ablation is not an option or you prefer a drug. | Dofetilide is less toxic but needs a hospital start. Sotalol is less strong but safer. Ablation is a procedure but spares your organs. |
| Rate control alone (beta-blocker plus a blood thinner) | AFib stays. Some people still feel tired, get short of breath with activity, or feel a racing heart. | It is simple, and most people do fine on it. The AFFIRM trial and others found the same survival as rhythm control in older patients with no symptoms. | Dofetilide or ablation can control the rhythm if symptoms stay despite good rate control. Watchful waiting is fine only when symptoms are slight. |
Common Misconceptions
| Myth | Reality |
|---|---|
| Dofetilide is just another pill — I should be able to start it at home. | The FDA requires a 3-day start in the hospital on a heart monitor. This is not optional. Bad rhythms show up most in the first hours and days. Fast help right then can save your life. |
| If I miss a dose, I should double up on the next one. | Never take a double dose. Skip the dose you missed. Take your next dose at the normal time. Doubling up can set off torsades de pointes. |
| Dofetilide is the strongest rhythm drug, so I should be on it. | Dofetilide fills a special role. It is a top pick for AFib when the heart is weak or the arteries are blocked and flecainide is not safe. For most healthy hearts, ablation or amiodarone may be better. The right drug depends on the patient. |
| Once I am steady on dofetilide, the labs and EKGs are just a formality. | Your kidneys can change with age, with how much you drink, or when you are sick. When they slow down, the drug builds up. Without checks, the QTc can stretch with no warning and set off a bad rhythm. The labs and EKGs matter, for life. |
| I can take any antibiotic if I get an infection. | Trimethoprim-sulfa antibiotics must never be taken with dofetilide. Some others, like certain quinolones and macrolides, stretch the QT interval. Always call us before you start any new drug, even one you buy over the counter. |
| Once my rhythm is back to normal, I can stop dofetilide. | Dofetilide does not cure AFib. It controls it. If you stop, AFib usually comes back within weeks. If you want to come off the drug, ablation may be a better long-term plan. |
| Tikosyn is too dangerous — no one should take it. | When it is prescribed and watched the right way, dofetilide is safe and works well. The 3-day hospital start is there to make it safe. Many patients take it for decades with no problems. |
Possible Complications
Knowing what can go wrong helps you spot problems early. Most complications are uncommon, especially with treatment.
| Where / What | What Can Happen |
|---|---|
| Torsades de pointes (TdP) | A fast, deadly rhythm. It is the main reason for the 3-day hospital start. The risk is highest at the start. It also rises if your kidneys slow down, your potassium or magnesium is low, or a clashing drug is added. |
| Too much QT stretch | Dofetilide stretches the QT interval on purpose — that is how it works. But if the QTc goes past 500 ms (or 550 ms with a heart-block problem), we must lower the dose or stop the drug. An EKG catches this. |
| Drug clashes | Five drugs must never be taken with it: cimetidine, ketoconazole, trimethoprim (including Bactrim), verapamil, and hydrochlorothiazide. Many other drugs stretch the QT, so you must avoid them or be watched. This is why we review every new drug. |
| Kidney slowdown | The kidneys clear dofetilide from your body. If they slow down, blood levels rise and so does the risk. Routine creatinine and potassium checks catch this early. We may lower the dose or stop the drug. |
| Headache, chest pain, nausea, dizziness | These side effects are common and usually mild. Tell us about any that stay or get worse. At times they point to a deeper problem. |
| It can stop working over time | AFib can come back even on dofetilide. If it does, we have options. We can raise the dose (rarely, and only in the hospital), switch you to amiodarone, or send you for ablation. |
Points to Know
Shown in English for your safety — this section is not automatically translated. Confirm with your doctor or call the office.
If you remember nothing else, remember these key points.
- Take dofetilide at the same two times each day, exactly 12 hours apart.
- Never take a double dose to make up for one you missed. Just skip it.
- Stay away from grapefruit juice. Try not to make big changes in how much you drink or how much salt you eat. These can change your blood levels.
- Tell every doctor, dentist, and pharmacist that you take dofetilide BEFORE you take any new drug.
- Show pharmacists the drug list in this guide when you fill a new prescription.
- Get your kidney number (creatinine) and your potassium checked at least every 3 months.
- Call us right away if you start to throw up, have diarrhea, or get dehydrated. These can drop your potassium and set off a bad rhythm.
- Bring this guide and a list of all your medicines to every visit.
When to Call Us — and When to Call 911
Shown in English for your safety — this section is not automatically translated. Confirm with your doctor or call the office.
If you are not sure, call. We would rather hear from you twice than miss a real problem.
- A racing, pounding, or fluttering heartbeat — call us today.
- Fainting or nearly fainting — call 911.
- Chest pain or pressure — call 911.
- Bad dizziness or weakness — call us today.
- Throwing up or diarrhea for more than 24 hours — call us today. This can drop your potassium.
- Any new drug from another doctor — call us BEFORE you fill it.
- A big weight change, new swelling, or worse shortness of breath — call us this week.
- More than one dose missed in a row — call us before you start again.
Office: (727) 943-5200
Trusted Resources
Independent, evidence-based pages we recommend for deeper reading.
- Cleveland Clinic — Dofetilide (Tikosyn) — An easy-to-read look at how to use dofetilide and stay safe.
- MedlinePlus — Dofetilide — A plain-language drug page from the NIH. Covers doses, missed doses, and drug clashes.
- Pfizer Tikosyn Patient Medication Guide — The maker's patient guide. It covers full use and the REMS safety program.
- American Heart Association — Treatments for AFib — An AHA look at ways to control the AFib rhythm, including dofetilide.
Sources Used to Build This Guide
- Pfizer Tikosyn Prescribing Information / FDA Label [guideline] — Source-of-truth dosing table by CrCl, contraindicated drug list, 3-day inpatient initiation requirement, and the Tikosyn REMS prescriber/pharmacy requirements.
- Torp-Pedersen et al — DIAMOND-CHF: Dofetilide in Patients with Severe Heart Failure (NEJM 1999) [clinical_trial] — Established mortality-neutral safety of dofetilide in patients with severe LV dysfunction (a niche where amiodarone or sotalol are problematic). Anchors the heart-failure use case.
- Singh et al — SAFIRE-D: Symptomatic Atrial Fibrillation Investigation and Randomized Evaluation of Dofetilide (Circulation 2000) [clinical_trial] — Demonstrated dofetilide's efficacy for both conversion of atrial fibrillation/flutter and maintenance of sinus rhythm vs placebo. Foundation for the FDA indication.
- January et al — 2019 AHA/ACC/HRS Focused Update on Atrial Fibrillation Guideline (Circulation 2019) [guideline] — Places dofetilide in the rhythm-control algorithm — appropriate for patients with heart failure or coronary disease where flecainide/propafenone are contraindicated.
- Cleveland Clinic — Dofetilide (Tikosyn) [clinical] — Patient-friendly overview of dofetilide use, side effects, and inpatient initiation rationale.
- MedlinePlus — Dofetilide [clinical] — NIH-curated drug monograph for patients — dosing, missed-dose handling, side effects, and drug interactions in plain language.
- Mounsey & DiMarco — Dofetilide (Circulation 2000) [clinical_trial] — Mechanism review — selective IKr blockade, dose-dependent QT prolongation, and renal clearance basis for CrCl-adjusted dosing.
- Reiffel et al — Practical Considerations in Dofetilide Initiation (Pharmacotherapy 2019) [clinical_trial] — Real-world initiation experience: 3-day telemetry monitoring, QTc thresholds for dose reduction or discontinuation, and most common reasons for non-completion.
