Disopyramide (3737-09-5) is a clinically useful sodium channel blocker used as an antiarrhythmic for treatment of ventricular tachycardia¹ and hypertrophic cardiomyopathy².  It decreases the rate of diastolic depolarization, decreases the upstroke velocity and increases the action potential duration of normal cardiac cells. It decreases the disparity between infarcted and normal myocardium refractory periods.  Disopyramide has no effect on α or β-adrenergic receptors but does display significant anticholinergic effects.³

References/Citations

1) Hell et al. (1978), Disopyramide: a review of its pharmacological properties and therapeutic use in treating cardiac arrhythmias; Drugs 115 331
2) Verlinden et al. (2015), Disopyramide for Hypertrophic Cardiomyopathy: A Pragmatic Reappraisal of an Old Drug; Pharmacotherapy, 35 1164
3) Nakajima et al. (1989), Anti-Cholinergic Effects of Quinidine, Disopyramide, and Procainamide in Isolated Atrial Myocytes: Mediation by Different Molecular Mechanisms; Circ. Res., 64 297