Side Effects of Tikosyn (Dofetilide)
Tikosyn (dofetilide) can cause serious side effects, most notably a potentially fatal type of abnormal heartbeat called Torsade de Pointes, which requires mandatory hospitalization for the first 3 days of treatment to establish the appropriate dose and monitor for complications.
Major Side Effects
Cardiac Side Effects
- Torsade de Pointes: The most serious side effect, occurring in 0.8-1.5% of patients taking oral dofetilide and 3-4% with intravenous administration 1
- QT interval prolongation: Dose-dependent effect that can lead to Torsade de Pointes 2, 3
- Bradycardia: Abnormally slow heart rate 4
- Hypotension: Low blood pressure 4
Common Non-Cardiac Side Effects
- Headache: One of the most frequently reported side effects 2
- Chest pain: Common complaint among users 2
- Dizziness: May affect balance and daily activities 2
Risk Factors for Serious Side Effects
Patients at higher risk for developing Torsade de Pointes include:
- Female gender
- Advanced age
- Hypokalemia (low potassium)
- Hypomagnesemia (low magnesium)
- Bradycardia
- Congestive heart failure
- Renal dysfunction
- Baseline QT prolongation
- Concomitant use of other QT-prolonging medications 5
Drug Interactions
Contraindicated Medications
Dofetilide should NOT be taken with:
- Verapamil
- Cimetidine
- Ketoconazole
- Trimethoprim alone or with sulfamethoxazole
- Prochlorperazine
- Megestrol
- Dolutegravir
- Hydrochlorothiazide (alone or in combination) 2, 5
These medications can increase the risk of QT prolongation and Torsade de Pointes when combined with dofetilide.
Monitoring Requirements
Due to the risk of serious arrhythmias:
- Treatment must be initiated in a hospital setting
- Continuous cardiac monitoring for at least 3 days
- ECG monitoring before and after dosing
- Regular assessment of kidney function
- Monitoring of electrolytes, particularly potassium and magnesium 2
- Discontinuation if QT interval exceeds 500 ms or increases by >60 ms from baseline 5
Dosing Considerations
- Dosing must be individualized based on QTc interval and renal function
- Dose adjustment is required for patients with renal impairment
- Dofetilide is contraindicated in patients with creatinine clearance <20 mL/min 4
Signs of Electrolyte Imbalance
Patients should be alert for signs of electrolyte imbalance, which can increase the risk of arrhythmias:
- Severe diarrhea
- Unusual sweating
- Vomiting
- Loss of appetite
- Increased thirst 2
When to Seek Immediate Medical Attention
Patients should call their doctor and go to the hospital immediately if they:
- Feel faint
- Become dizzy
- Experience a fast heartbeat 2
These symptoms could indicate the development of a serious arrhythmia requiring immediate medical intervention.
Special Populations
Dofetilide should be used with caution in:
- Elderly patients
- Patients with heart failure
- Patients with structural heart disease
- Patients with renal impairment (requires dose adjustment) 4, 5
Understanding these side effects and following proper monitoring protocols is essential for the safe use of Tikosyn (dofetilide) in managing atrial fibrillation and atrial flutter.