Disopyramide is a class IA antiarrhythmic drug which acts via blockade of sodium channels depressing phase 0 of the action potential. Disopyramide possesses significant negative inotropic, anticholinergic effects and enhances AV nodal conduction.
Disopyramide is used to maintain sinus rhythm in patients with atrial fibrillation. Due to potential adverse effects and the availability of other drugs, disopyramide is rarely used for this purpose. Vagally mediated atrial fibrillation responds well to disopyramide.
Disopyramide is the historical treatment for hypertrophic obstructive cardiomyopathy due to the significant negative inotropic effects. It is currently recommended only for persistent symptoms if non-dihydropyridine calcium channel blockers and beta-blockers fail. Patients on disopyramide should also take one of the above concomitantly since disopyramide enhances AV nodal conduction causing rapid conduction should atrial fibrillation or atrial flutter develop.
Disopyramide can be used for the treatment of ventricular arrhythmias, although is rarely utilized for this indication.
Anticholinergic side effects including xerostomia (dry mouth), urinary retention, visual disturbances and decreased perspiration.
Disopyramide can prolong the QT interval resulting in polymorphic ventricular tachycardia.
Fatigue, hypotension, dizziness, weakness
Atrial fibrillation triggered by situations of vagal stimulation has been well described (nausea, vomiting, abdominal pain, severe coughing, young healthy athletes with high vagal tone etc...). In this scenario, the historical antiarrhythmic drug which has been successful is disopyramide. The significant anticholinergic activity making it more effective in this situation.
By Steven Lome