Overdose : מינון יתר

4.9 Overdose

Overdose with flecainide is a potentially life-threatening medical emergency.
Increased drug susceptibility and plasma levels exceeding therapeutic levels may also result from drug interactions (see section 4.5).

The symptoms of flecainide overdose progress according to the intake dose, the time that detoxification measures are initiated, and the functional status of the myocardium.
Overdose can induce cardiac and extracardiac adverse effects; these are listed in section 4.8. Cases of severe intoxication, accidental or suicidal, may induce asystole, respiratory arrest and an acute increase in the endocardial stimulation threshold.

No specific antidote is known.


There is no known way to rapidly remove flecainide from the system; however, forced alkaline diuresis may theoretically be useful (for details of the pH-value-specific elimination of flecainide, see section 5.2).

The treatment should include the following:

General measures:
-   Stop or reduce the dose of flecainide,
-   Intensive medical measures to address the symptoms.
Measures to address SA block and AV block (second- or third- degree): -   Parasympatholytic therapy using atropine or ipratropium bromide. Sympathicotonic therapy using orciprenaline; possibly pacemaker therapy.

Measures to address intraventricular blocks (bundle branch block):
-   Stop or reduce the dose of flecainide; possibly pacemaker therapy. If electrical stimulation with a pacemaker is unsuccessful, it is possible to use high doses of orciprenaline to try and improve myocardial function.

Measures to address acute cardiac decompensation, possibly with low blood pressure: 
-     Stop flecainide, rapid IV loading with cardiac glycosides; if there is existing pulmonary oedema, intravenous administration of furosemide, preload reduction through administration of high-dose nitrates, if required, catecholamines (e.g. adrenaline and/or dopamine/dobutamine and/or isoproterenol). Circulation support using an intra-aortic balloon pump can be attempted.

Specific measures in severe intoxication:
-     For severe hypotension and bradycardia (usually in unconscious patients): Atropine 0.5–1 mg IV, adrenaline 0.5–1 mg IV, possibly adrenaline continuous drip infusion. The drip rate is based on the clinical effect; possibly parasympatholytic therapy with atropine/ipratropium bromide; possibly antibradycardia pacemaker stimulation.
-     For cerebral seizures: e.g. diazepam IV, secure the airways, intubation if necessary and controlled ventilation under relaxation (e.g. pancuronium 2–6 mg).
For circulatory arrest due to asystole or ventricular fibrillation: Basic measures for cardiopulmonary resuscitation (ABC rule):
-     Airway: clear the airway or intubate.
-     Breathing: provide rescue breathing, where possible with high-flow oxygen therapy.
-     Circulation: i.e. external cardiac massage (if necessary for several hours!).

Adrenaline 0.5–1 mg IV or diluted with 10 mL isotonic sodium chloride solution via intratracheal tube if there is no central venous access near the heart. Depending on the clinical effect, the administration of adrenaline can be repeated several times.

-     For ventricular fibrillation: Defibrillation. For refractory VF, 5–15 mval potassium chloride IV then repeat defibrillation.
-     If it is not possible to induce conversion of malignant ventricular tachycardia using standard measures (see above), it is justifiable to attempt antitachycardia pacemaker stimulation (e.g. overdrive suppression).

-     Balance the metabolic acidosis with sodium carbonate 8.4%, initially at 1 mL/kg BW IV; repeat after 15 minutes.

Intravenous administration of lipid emulsions or extracorporeal membrane oxygenation (ECMO) can be considered depending on the specific case
-     Attempt to improve heart and kidney function through infusions with catecholamines added (e.g. adrenaline and/or dopamine/dobutamine).
-     - Generally speaking for class I antiarrhythmics, conduction disorders caused by toxicity can be antagonistically affected through intravenous administration of concentrated sodium ion solution (approximately 100 mval sodium chloride solution IV). A serum sodium level of 145–150 mval/L should not be exceeded.

-     - The administration of 25–100 mg dexamethasone or betamethasone IV and/or 40% mannitol or sorbitol solution, 1 mL/kg BW IV can be attempted for the purpose of cerebral oedema prophylaxis or therapy.