Key takeaways
Quinidine and disopyramide (Norpace) are both antiarrhythmic medications used to treat abnormal heart rhythms, but they have some key differences. Quinidine is available only in generic form and is used for treating and preventing atrial fibrillation, atrial flutter, and ventricular arrhythmias. Disopyramide, on the other hand, is available as both a brand (Norpace) and generic for its immediate-release form, but only as a brand for its extended-release form (Norpace CR). Disopyramide is primarily used for ventricular arrhythmias and is sometimes used off-label for atrial fibrillation and hypertrophic cardiomyopathy, though it is not a first-choice treatment. Quinidine works by blocking sodium channels to slow down abnormal heart rhythms, while disopyramide also slows down electrical activity in the heart but has a higher risk of causing low blood pressure and heart failure. Both medications require close monitoring by your provider due to their potential for serious side effects, including life-threatening arrhythmias. Common side effects of quinidine include diarrhea and lightheadedness, whereas disopyramide often causes dry mouth, difficulty urinating, and constipation.
