Special Warning : אזהרת שימוש

4.4       Special warnings and precautions for use

Intravenous use of flecainide should normally be carried out under ECG and blood pressure monitoring. It is advisable to ensure that equipment is available to provide any support needed during administration.
In particular in cases of severe heart, liver or kidney dysfunction where antiarrhythmic therapy with flecainide is necessary, or where patients are treated with concomitant flecainide and amiodarone or flecainide and cimetidine, any adjustment of the therapy, dose changes and long-term therapy shall be done by repeated ECG checks with simultaneous checks of the flecainide plasma level (see section 4.2).
Direct hospital or specialist supervision is also required for:

-   Patients with AV nodal reciprocating tachycardia; arrhythmias associated with Wolff- Parkinson-White syndrome and similar conditions with accessory pathways -   Paroxysmal atrial fibrillation in patients with disabling symptoms 
Electrolyte imbalances should be corrected before using flecainide. Hypokalaemia or hyperkalaemia can influence the effects of class I antiarrhythmics. Hypokalaemia may occur in patients taking concomitant diuretics, corticosteroids or laxatives.

Severe bradycardia or pronounced hypotension should be corrected with medications before using flecainide.

In case of pronounced cardiac output disturbance (heart failure NYHA class III-IV and/or LVEF less than 35%), treatment of life-threatening ventricular cardiac arrhythmias with flecainide should only occur once the heart failure is compensated through the use of additional medications to increase cardiac output.

Since flecainide elimination from the plasma may be significantly delayed in patients with significant hepatic and renal impairment (creatinine clearance less than 35 mL/min/1.73 m2), flecainide should not be used in these patients unless the potential benefits clearly outweigh the risks. Plasma level monitoring is strongly recommended for these patients.


Flecainide is known to increase the endocardial pacing threshold, i.e. it decreases endocardial pacing sensitivity. This effect is reversible and is more marked in acute pacing applications than in chronic ones.
Flecainide has a selective effect that increases the refractory period of anterograde and especially of retrograde conduction. In most patients, this presents on ECG as a widening of the QRS complex by 12–20% and prolongation of the QTc interval. Consequently, the effect on the JT interval is only slight. Nevertheless, there have been reports of prolongation of the JT interval of up to 4%. This action is less marked than that observed with the class Ia antiarrhythmic drugs.
Flecainide should thus be used with caution in all patients with permanent or temporary pacemakers, and should not be administered to patients with existing poorly managed thresholds or non-programmable pacemakers unless suitable pacing rescue is available to handle emergencies.

Generally, a doubling of either pulse width or voltage is sufficient to restore pacemaker function, but it may be difficult to obtain ventricular thresholds less than 1 volt at initial implantation in the presence of flecainide.

The minor negative inotropic effect of flecainide may assume importance in patients predisposed to cardiac failure. Difficulty has been experienced in defibrillating some patients, especially in those with pre-existing heart disease with cardiac enlargement, a history of myocardial infarction, arteriosclerotic cardiovascular disease and heart failure.
Flecainide, like other antiarrhythmics, may cause proarrhythmic effects, i.e. it may increase the severity or frequency of an existing arrhythmia (see section 4.8).
Flecainide should be avoided in patients with structural heart disease or abnormal left ventricular function (see section 4.8).
Flecainide should be used with caution in patients with acute onset of atrial fibrillation following cardiac surgery.
In a large-scale, placebo-controlled clinical trial, in post-myocardial infarction patients with asymptomatic arrhythmias, oral flecainide was associated with 2.2-fold higher incidence of mortality or non-fatal cardiac arrest as compared with a placebo. In that same study, an even higher mortality rate was observed in patients treated with flecainide who had more than one myocardial infarction.

Brugada syndrome may be unmasked by flecainide therapy. In the case of ECG changes that develop during treatment with flecainide that may indicate Brugada syndrome, consideration should be given to discontinuing the treatment.

The rate of flecainide elimination from plasma may be reduced in the elderly. This should be taken into consideration when making dose adjustments.

Dairy products (milk, infant formula and possibly yoghurt) may reduce the absorption of flecainide in children and infants. Flecainide is not approved for use in children under 12 years of age; however, flecainide toxicity has been reported during treatment in children who reduced their intake of milk, and in infants who were switched from milk formula to dextrose-based products.

Since flecainide is a narrow therapeutic index drug, it requires caution and close monitoring when switching a patient to a different formulation.

Note:
During use, it is essential to consider that no evidence has yet been discovered for any class I antiarrhythmic that treating arrhythmias extends life.

Tambocor contains 37.6 mg sodium per ampoule, equivalent to 1.9% of the WHO recommended maximum daily sodium intake of 2 g in food.



Effects on Driving

4.7 Effects on ability to drive and use machines

The presence of visual disturbances (e.g. double vision) or effects on the central-nervous system (tiredness, dizziness) can impair responses to the extent that it reduces the ability to drive, operate machinery or work without a secure support. These effects are multiplied when the drug is combined with alcohol.