Name: Disopyramide (Norpace)
Class: Antidysrhythmic Agent (Class IA)
Mechanism: Binds to open and inactivated Na+ channels and prevents Na+ influx ® slowing of the rapid upstroke during phase 0. Also decreases the slope of phase 4 spontaneous depolarization. Prolongs repolarization. Inhibits arrhythmias due to normal automaticity. Intermed. speed of dissociation from Na+ channels. Peripheral vasoconstriction. The stereoisomers have opposite effects on repolarization.
Absorption:
Dist.:
Metabolism.: Hepatic.
Excretion, t½: Urine.
Toxicity/S.E.s: Proarrhythmic effects, negative inotropy, infranodal conduction block, DILQT. Anticholinergic effects—dry mouth, urinary retention, blurred vision, constipation. N/v/d, abd. pain. Less GI intolerance than quinidine.
Utility: Alt. to procainamide or quinidine for treatment of ventricular arrhythmia.
Special Features: