Class Ia antiarrhythmic with antimuscarinic activity
ATC code: C01BA03 (Disopyramide)
Brand names
Norpace, Rythmodan
Blocks fast sodium channels at phase 0 and IKr potassium channels at phase 3, prolonging repolarisation and QT. Strong antimuscarinic activity adds adverse effects (dry mouth, urinary retention). Metabolised by CYP3A4 and to a lesser extent renally.
Third line
Disopyramide is a third-line antiarrhythmic for ventricular tachycardia and atrial fibrillation when amiodarone, dronedarone and catheter ablation fail. AEMPS and restrict use because of QT prolongation, neuropathy risk and pronounced antimuscarinic effects (especially in the elderly).
3 pairs found. Sorted from critical to minor.
Mechanism
Amiodarone is the strongest clinical QT prolonger and CYP3A4 inhibitor. With disopyramide additive QT effect (each prolongs 30-50 ms).
Symptoms
QTc above 550 ms, syncope, torsades de pointes.
Management
Combination contraindicated. Choose one antiarrhythmic.
Sources
Mechanism
Clarithromycin is a strong CYP3A4 inhibitor; disopyramide rises 3-fold. Additive QT prolongation.
Symptoms
QT prolongation, syncope, torsades de pointes.
Management
Combination contraindicated. Switch clarithromycin to azithromycin.
Mechanism
Erythromycin inhibits CYP3A4 (disopyramide metabolism) and itself prolongs QT. Dual torsades risk.
Symptoms
QTc above 500 ms, syncope, torsades de pointes within 3-7 days.
Management
Combination contraindicated. Alternative – azithromycin (no CYP3A4 inhibition or QT effect).
Opens the checker prefilled with this drug. Pick the second one from your regimen.
Limited data. Use only when no alternative exists.
Passes into breast milk. Breastfeeding not recommended.
Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.
Disopyramide is evaluated for the following indications with varying evidence strength: Ventricular arrhythmia (evidence tier C). See the full indication matrix with dosing and citations above on this page.
Common side effects of Disopyramide (≥ 1 in 100): Dry mouth, Urinary retention, Constipation, Blurred vision, QT prolongation. See the Safety section for uncommon and serious reactions.
FDA category C. Limited data. Use only when no alternative exists.
Passes into breast milk. Breastfeeding not recommended.
Disopyramide is contraindicated in: Second/third-degree AV block without pacemaker; Cardiogenic shock; Closed-angle glaucoma; Urinary retention (BPH); Combination with QT-prolonging drugs. Full list in the Safety section.