Flecainide
Mechanism :
Flecainide has local anesthetic activity and belongs to the membrane stabilizing (Class 1) group of antiarrhythmic agents; it has electrophysiologic effects characteristic of the IC class of antiarrhythmics. Effects upon atrioventricular (AV) nodal conduction time and intra-atrial conduction times, are less pronounced than those on ventricular conduction velocity. Significant effects on refractory periods were observed only in the ventricle.
. The antiarrhythmic actions are mediated through effects on sodium channels in Purkinje fibres. Flecainide is a sodium channel blocker, binding to voltage gated sodium channels. It stabilizes the neuronal membrane by inhibiting the ionic fluxes required for the initiation and conduction of impulses. Ventricular excitability is depressed and the stimulation threshold of the ventricle is increased during diastole.
Possesses local anaesthetic and moderate negative inotropic effects.
Indication :
- Arrhythmias
- Supraventricular tachycardia- re-entry type
- Ventricular ectopic
- Ventricular tachycardia
- WPW syndrome
- Paroxysmal atrial fibrillation
Contraindications :
Flecainide is contraindicated in patients with pre-existing second- or third-degree AV block, or with right bundle branch block when associated with a left hemiblock (bifascicular block), unless a pacemaker is present to sustain the cardiac rhythm should complete heart block occur, and in the presence of cardiogenic shock or known hypersensitivity to the drug.
Dosing :
Under 6 months.
Dose:
100 mg/m²/day orally in 2-3 divided doses. Start: 50 mg/m²/day in infants <6 months and 100 mg/m²/day in those above 6 months. Increase dose every 4 days. Max: 200 mg/m²/day.
Alternately start 1-3 mg/kg/day PO divided 8 hourly, increase to 3-6 mg/kg/day.
Note: After 5 doses/steady-state, obtain ECG after initiation or change of dose; obtain plasma trough Flecainide levels 1 hour pre-dose. Usual trough plasma levels: 0.2-1 mcg/mL.
Adverse Effect :
New or worsened arrhythmias in patients with PSVT and in patients with PAF, new or exacerbated ventricular arrhythmias in patients with PVCs, non-sustained or sustained VT, photosensitivity, allergic skin reactions, nausea, constipation, vomiting, elevation of serum alkaline phosphatase, serum transaminase levels, headache, transient dizziness, light-headedness, transient visual disturbances.
Interaction :
Beta blockers: The possibility of additive negative inotropic effects of beta blockers and flecainide.
Amiodarone: Plasma flecainide levels may increase two-fold or more in some patients.
Quinidine: Might increase the plasma concentrations of flecainide in patients that are on chronic flecainide therapy.
Renal Dose :
Dose in Renal Impairment GFR (mL/min)
| 20-50 | See ‘Other Information |
| 10-20 | See ‘Other Information |
| <10 | See ‘Other Information |
Dose in Patients undergoing Renal Replacement Therapies
| CAPD | ≈1% dialysed. Dose as in GFR<10 mL/min |
| HD | ≈1% dialysed. Dose as in GFR<10 mL/min |
| HDF/High flux | Unknown dialysability. Dose as in GFR<10 mL/min |
| CAV/VVHD | Minimal removal. Dose as in GFR=10–20 mL/min |
Hepatic Dose :
There is slower elimination in presence of liver disease. Frequent and early plasma drug monitoring is required for patients with severe hepatic disease. Adjust dosage at intervals of more than 4 days. Use in patients with hepatic impairment only if benefits clearly outweigh the risks.