Washout Period for Tikosyn (Dofetilide)
If you need to discontinue Tikosyn before starting another potentially interacting drug, a washout period of at least 2 days is required 1.
Key Washout Scenarios
Stopping Tikosyn Before Starting Other Medications
When Tikosyn must be discontinued to allow dosing of other potentially interacting drugs, you must wait a minimum of 2 days (48 hours) before initiating the new medication 1. This washout period allows adequate clearance of dofetilide from the system to prevent dangerous drug interactions, particularly with medications that affect renal cation transport or QT interval.
Switching FROM Other Antiarrhythmics TO Tikosyn
The reverse scenario requires different considerations:
Class I or other Class III antiarrhythmics: Withdraw for a minimum of 3 plasma half-lives before starting Tikosyn 1
Amiodarone: This requires special attention due to its extremely long half-life. The FDA label mandates that Tikosyn should not be initiated until amiodarone plasma levels are below 0.3 mcg/mL OR amiodarone has been withdrawn for at least 3 months 1. However, emerging research suggests this may be overly conservative in select patients with ICDs, where a 7-day washout has been studied 2.
Clinical Context and Rationale
The 2-day washout when stopping Tikosyn is based on dofetilide's pharmacokinetics. Dofetilide is primarily eliminated by renal cation secretion, and the washout period ensures adequate drug clearance before introducing medications that could interact through this pathway or affect QT interval prolongation.
Important Caveats
- Renal function matters: Patients with impaired renal function may require longer washout periods since dofetilide elimination is prolonged
- QT monitoring: The concern with inadequate washout is cumulative QT prolongation and risk of Torsades de Pointes
- The 3-month amiodarone rule: While the FDA mandates 3 months or documented low levels, one retrospective study in ICD patients showed safety with rapid switching after just 7 days 2, though this remains off-label and requires careful patient selection