From the Guidelines
Disopyramide should not be used as a first-line treatment for atrial fibrillation due to its potential to cause torsade de pointes, heart failure, and other adverse effects, and should only be considered in patients with vagally induced AF or when other treatments have failed 1.
Introduction to Disopyramide
Disopyramide is a Class IA antiarrhythmic medication used to treat irregular heart rhythms, particularly ventricular arrhythmias. It works by slowing electrical conduction in the heart, stabilizing the cardiac membrane, and prolonging the refractory period.
Dosage and Administration
The typical adult dosage of disopyramide ranges from 400-750 mg per day, as indicated in the guidelines for the management of patients with atrial fibrillation 1. Treatment usually begins with lower doses that may be adjusted based on patient response and plasma levels.
Side Effects and Precautions
Disopyramide has significant anticholinergic side effects, including dry mouth, urinary retention, constipation, and blurred vision. It can also cause hypotension and may worsen heart failure due to its negative inotropic effect. The medication should be used cautiously in patients with glaucoma, prostate enlargement, myasthenia gravis, or impaired liver or kidney function. Blood levels should be monitored, especially in patients with renal impairment, as the drug is primarily excreted by the kidneys.
Clinical Use
Disopyramide is now less frequently used due to its side effect profile and the availability of newer antiarrhythmic medications with better safety profiles. According to the guidelines for the management of atrial fibrillation, disopyramide is not favored unless amiodarone fails or is contraindicated 1. However, the anticholinergic activity of long-acting disopyramide makes it a relatively attractive choice for patients with vagally induced AF 1.
Key Considerations
- Disopyramide should be used with caution in patients with heart failure, as it can worsen the condition 1.
- The medication should be avoided in patients with a history of torsade de pointes or other proarrhythmic conditions 1.
- Disopyramide can interact with other medications, including beta-blockers and other antiarrhythmic agents, and should be used with caution in patients taking these medications 1.
- The patient should be alerted to the potential significance of symptoms such as syncope, angina pectoris, or dyspnea, and warned about the use of noncardiac drugs that can prolong the QT interval 1.
From the FDA Drug Label
Disopyramide phosphate capsules are indicated for the treatment of documented ventricular arrhythmias, such as sustained ventricular tachycardia, that, in the judgment of the physician, are life-threatening. Treatment of patients with asymptomatic ventricular premature contractions should be avoided. The use of disopyramide as well as other antiarrhythmic agents should be reserved for patients with life-threatening ventricular arrhythmias
The main indications for Disopyramide are:
- Life-threatening ventricular arrhythmias, such as sustained ventricular tachycardia Disopyramide should not be used to treat:
- Asymptomatic ventricular premature contractions
- Lesser arrhythmias unless they are life-threatening 2 2
From the Research
Overview of Disopyramide
- Disopyramide is a class IA antiarrhythmic drug, similar to quinidine and procainamide 3
- It is used to treat cardiac arrhythmias, particularly ventricular and atrial arrhythmias 4
- Disopyramide has a negative inotropic effect on cardiac muscle, which can be significant in patients with pre-existing left ventricular dysfunction 3
Pharmacological Properties
- Disopyramide inhibits the fast inward sodium current and decreases the maximum rate of rise and amplitude of the cardiac action potential 3
- It can cause a prolonged Q-T interval and, to a lesser extent, QRS duration at therapeutic concentrations 3
- Disopyramide is largely excreted unchanged and dosage should be reduced in patients with impaired renal function 4
Therapeutic Use
- Disopyramide has been shown to be effective in treating premature atrial and ventricular contractions, and is often better tolerated than quinidine 4
- It may be used prophylactically after myocardial infarction to reduce the incidence of reinfarction and mortality rate 4
- However, further well-designed trials are needed to determine its routine use in infarct patients 4
Side Effects
- Disopyramide can cause anticholinergic side effects, such as dry mouth and difficulty in urination 4
- It can also exert a negative inotropic action on cardiac muscle, leading to development of acute heart failure 4
- Disopyramide may precipitate ventricular tachycardia or ventricular fibrillation, and should be used cautiously in patients with the sick sinus syndrome 5
- Torsade de pointes ventricular tachycardia is a complication of disopyramide, similar to quinidine 6