From the FDA Drug Label
The apparent plasma half-life averages about 20 hours and is quite variable (range, 12 to 27 hours) after multiple oral doses in patients with premature ventricular contractions (PVCs) With multiple dosing, plasma levels increase because of its long half-life with steady-state levels approached in 3 to 5 days; once at steady-state, no additional (or unexpected) accumulation of drug in plasma occurs during chronic therapy In patients, free (unconjugated) plasma levels of the two major metabolites are very low (less than 0. 05 mcg/mL) When urinary pH is very alkaline (8 or higher), as may occur in rare conditions (e.g., renal tubular acidosis, strict vegetarian diet), flecainide elimination from plasma is much slower The elimination of flecainide from the body depends on renal function (i.e., 10 to 50% appears in urine as unchanged drug) With increasing renal impairment, the extent of unchanged drug excretion in urine is reduced and the plasma half-life of flecainide is prolonged Under one year of age, currently available data are limited but suggest that the half-life at birth may be as long as 29 hours, decreasing to 11 to 12 hours by three months of age and 6 hours by one year of age In children aged 1 year to 12 years the half-life is approximately 8 hours In adolescents (age 12 to 15) the plasma elimination half-life is approximately 11 to 12 hours From age 20 to 80, plasma levels are only slightly higher with advancing age; flecainide elimination from plasma is somewhat slower in elderly subjects than in younger subjects
Key Points:
- The plasma half-life of flecainide averages about 20 hours with a range of 12 to 27 hours.
- The time it takes for flecainide to be eliminated from the body depends on renal function and can be affected by urinary pH.
- Age can also impact the elimination half-life of flecainide, with half-lives ranging from 6 hours at one year of age to 29 hours at birth.
- It is estimated that it may take around 5 half-lives (approximately 100 hours or 4-5 days) for flecainide to be completely eliminated from the system, assuming normal renal function and urinary pH. 1
From the Research
Flecainide typically takes about 2-3 days to be completely eliminated from the body after stopping the medication. The drug has a half-life of approximately 12-27 hours in most patients with normal kidney and liver function, meaning it takes this amount of time for half of the drug to be cleared from your system 2. Complete elimination generally requires 4-5 half-lives, which translates to roughly 48-72 hours for most people. However, this timeframe can be longer in patients with liver or kidney impairment, as these organs are responsible for metabolizing and excreting the drug. Elderly patients may also experience slower clearance. Some key points to consider when stopping flecainide include:
- The pharmacokinetics of flecainide, with lower interindividual variability of absorption kinetics, no genetically determined formation of an active metabolite, and a more rapid distribution to myocardial tissue, are more favorable for episodic treatment as compared to propafenone 2.
- Flecainide is effective in converting recent onset atrial fibrillation, with conversion rates of 59% and 68% of patients at 3 h after a single oral dose of 300 mg 2.
- The safety of flecainide has been established, with no serious ventricular arrhythmia, other serious proarrhythmic effects, or serious non-cardiac adverse events observed 2. It's essential to note that even though the drug may be physically eliminated from your body within a few days, some of its cardiac effects might persist slightly longer as the heart tissue readjusts. If you're stopping flecainide before surgery or to switch to another antiarrhythmic medication, your doctor will typically provide specific guidance about the appropriate waiting period based on your individual health circumstances.