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Usage

Clinical Use

Ventricular and supraventricular arrhythmias

Drug interactions

Potentially hazardous interactions with other drugsAnti-arrhythmics: increased myocardial depression with other anti-arrhythmics; amiodarone and dronedarone increase risk of ventricular arrhythmias - avoid.Antibacterials: concentration possibly increased by azithromycin, clarithromycin and erythromycin (risk of toxicity); increased risk of ventricular arrhythmias with moxifloxacin - avoid; possibly increased risk of ventricular arrhythmias with telithromycin and delamanid; concentration reduced by rifamycins.Antidepressants: increased risk of ventricular arrhythmias with tricyclics; increased risk of ventricular arrhythmias with citalopram and escitalopram - avoid.Antifungals: increased risk of ventricular arrhythmias with ketoconazole - avoid; avoid with itraconazole.Antihistamines: increased risk of ventricular arrhythmias with mizolastine.Antihypertensives: increased myocardial depression and asystole with beta-blockers or verapamil; increased risk of ventricular arrhythmias with sotalol Antimuscarinics: increased risk of antimuscarinic side effects; increased risk of ventricular arrhythmias with tolterodine.Antivirals: concentration possibly increased by ritonavir, increased risk of toxicity; increased risk - avoid.

Metabolism

Disopyramide is partially metabolised in the liver by the cytochrome P450 isoenzyme CYP3A4. The major metabolite is mono-N-dealkylated disopyramide which retains some antiarrhythmic and antimuscarinic activity. The major route of excretion is through the kidney, about 50-60% as the unchanged drug, 20% as the N-dealkylated metabolite, and 10% as other metabolites. 64% of the N-dealkylated metabolite is excreted via the faeces.