AV nodal reciprocating tachycardia, arrhythmias associated w/ Wolff-Parkinson-White syndrome & similar conditions w/ accessory pathway. Paroxysmal atrial fibrillation in patients w/ disabling symptoms. Symptomatic sustained ventricular tachycardia. Premature ventricular contractions &/or nonsustained ventricular tachycardia which are causing disabling symptoms, where these are resistant to other therapy or when other treatment has not been tolerated. Maintenance of normal rhythm following conversion by other means.
Dosage/Direction for Use
Supraventricular arrhythmias 50 mg bd, if required may be increased to max: 300 mg daily. Ventricular arrhythmias Initially 1 tab bd, max: 400 mg daily.
Administration
May be taken with or without food.
Contraindications
Cardiac failure, patients w/ history of MI who has either asymptomatic ventricular ectopics or asymptomatic nonsustained ventricular tachycardia. Long-standing atrial fibrillation w/ no attempt to convert to sinus rhythm, haemodynamically significant valvular heart disease. Sinus nodal dysfunction, atrial conduction defects, 2nd degree or greater AV block, bundle branch block or distal block unless pacing rescue available.
Special Precautions
Prior electrolyte disturbances, significant hepatic impairment, patients w/ permanent pacemakers or temporary pacing electrodes; predisposition to cardiac failure. Patients w/ acute onset of atrial fibrillation following cardiac surgery.
Adverse Reactions
Most commonly, giddiness, dizziness, lightheadedness, visual disturbances, occasional nausea & vomiting. Proarrhythmia may occur in patients w/ structural heart disease &/or significant left ventricular impairment.
May cause rise in plasma digoxin. Possible additive -ve inotropic effects of β-blockers & other cardiac depressants. Enhanced elimination by enzyme inducers. Reduced dose by 50% w/ amiodarone.
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