Ventricular and supraventricular arrhythmias
Potentially hazardous interactions with other drugs
Anti-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.
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.
