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Norpace CR Side Effects

Generic name: disopyramide

Medically reviewed by Last updated on Dec 15, 2021.

Note: This document contains side effect information about disopyramide. Some of the dosage forms listed on this page may not apply to the brand name Norpace CR.

For the Consumer

Applies to disopyramide: oral capsule, oral capsule extended release


Oral route (Capsule; Capsule, Extended Release)

An increase in mortality has been reported in patients receiving encainide or flecainide after myocardial infarction for asymptomatic non life threatening ventricular arrhythmias. Considering the known proarrhythmic properties of disopyramide and the lack of evidence of improved survival for any antiarrhythmic drug in patients without life-threatening arrhythmias, the use of disopyramide as well as other antiarrhythmic agents should be reserved for patients with life-threatening ventricular arrhythmias.

Side effects requiring immediate medical attention

Along with its needed effects, disopyramide (the active ingredient contained in Norpace CR) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor as soon as possible if any of the following side effects occur while taking disopyramide:

More common

  • Dizziness, feeling of faintness
  • fainting
  • heartbeat sensations
  • shortness of breath
  • unusual tiredness

Less common

  • Chest pain
  • fast or slow heartbeat, rapid weight gain, swelling of feet or lower legs
  • lightheadedness
  • rash and/or itching


Signs and symptoms of hypoglycemia (low blood sugar)

Side effects not requiring immediate medical attention

Some side effects of disopyramide may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

  • Blurred vision
  • constipation
  • dry eyes, mouth, nose, or throat
  • problems with urination

Less common

  • Bloating or stomach pain
  • diarrhea
  • headache
  • impotence
  • loss of appetite
  • muscle weakness
  • nausea
  • nervousness
  • trouble in sleeping

For Healthcare Professionals

Applies to disopyramide: compounding powder, oral capsule, oral capsule extended release


Gastrointestinal side effects including anticholinergic side effects have been the most common cause of gastrointestinal complaints. Dry mouth (40%), constipation (11%) and nausea, pain/bloating/gas (3% to 9%) have been reported. Anorexia, diarrhea, and vomiting have occurred. Two cases of paralytic ileus have been reported. A case of oral mucosal ulceration has been associated with the (unapproved) sublingual use of disopyramide (the active ingredient contained in Norpace CR) [Ref]


Cardiovascular side effects have included arrhythmias, conduction disturbances, hypotension, and heart failure. Like other class I antiarrhythmic agents, disopyramide (the active ingredient contained in Norpace CR) can be proarrhythmic and decrease cardiac contractility. The risk of proarrhythmias may be increased in patients with left ventricular dysfunction. Various ventricular tachyarrhythmias accompanied by disopyramide-induced QT interval prolongation, including ventricular tachycardia or fibrillation and torsades de pointes, have been associated with usual therapeutic doses. Evidence of QRS segment or QT widening are indications to either reduce the dose or stop the drug. Conduction disturbances, including AV block, have occurred, and are more likely in patients with preexisting conduction disorders.[Ref]

Contributing factors towards the development of torsades de pointes included female gender, hypokalemia, underlying arrhythmias, mitral valve abnormalities, or congestive heart failure.

Hypotension, pulmonary edema, and frank cardiogenic shock have been associated with both the oral and intravenous administration of disopyramide. Most affected patients had underlying congestive heart failure.[Ref]

Nervous system

A patient developed a severe sensory-motor polyneuropathy after receiving disopyramide (the active ingredient contained in Norpace CR) 500 mg daily for 4 years. Symptoms did not respond to corticosteroids, but did resolve a few months after withdrawal of disopyramide.[Ref]

Nervous system side effects including anticholinergic symptoms have been reported. Other nervous system side effects have been rare, and included nervousness, insomnia, depression, and peripheral paresthesia or neuropathy.[Ref]


Genitourinary side effects were related to anticholinergic properties of the drug. Urinary hesitancy (10% to 40%) has occurred. Urinary retention, frequency, and urgency has been reported in up to 9% of patients. Recommended management consisted of lowering the dose, discontinuing the drug, or if necessary, using a cholinergic drug to counteract this effect. Sexual impotence has been reported.[Ref]


Hepatic side effects including reversible, dose-independent intrahepatic cholestasis, hepatocellular damage, and nonspecific hepatic inflammatory changes have been reported in rare cases where venous congestion secondary to heart failure was reasonably excluded. Manifestations of liver dysfunction usually appeared during the first week of treatment (malaise, dark urine) and resolved promptly upon discontinuation of the drug. In one review, 20 cases were reported during a 14-year period.[Ref]


Endocrine side effect have included hypoglycemia due to stimulation of insulin secretion and rare cases of hypokalemia and dyslipidemia. Hypoglycemia can occur in nondiabetic patients at therapeutic plasma disopyramide (the active ingredient contained in Norpace CR) levels.[Ref]

Elevated insulin levels have been measured during disopyramide-associated hypoglycemic episodes. Data have revealed that disopyramide blocks pancreatic ATP-sensitive potassium channels, enhancing insulin release. Other factors such as increased peripheral utilization of glucose or decreased glycogenolysis have not been fully evaluated.[Ref]


Immunologic side effects, such as the production of antinuclear antibodies and other immunologically-mediated changes associated with other class 1 antiarrhythmic agents, do not appear to occur during disopyramide (the active ingredient contained in Norpace CR) therapy.[Ref]


Dermatologic reactions have been reported rarely, usually presenting as a rash or pruritus.[Ref]


Ocular side effects of blurred vision (3% to 9%) have been associated with the anticholinergic effects of disopyramide (the active ingredient contained in Norpace CR) [Ref]


General body symptoms of fatigue, muscle weakness, malaise, and aches/pains have been reported in 3% to 9% of patients administered disopyramide (the active ingredient contained in Norpace CR) Rarely, fever has occurred.[Ref]


Psychiatric side effects including reversible psychiatric symptoms of psychosis have been reported rarely.[Ref]


Hematologic adverse effects of thrombocytopenia, and reversible agranulocytosis have occurred rarely.[Ref]


Gynecomastia has been reported.[Ref]


Respiratory difficulty has been reported rarely.[Ref]


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Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.