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Norpace CR Side Effects

Generic Name: disopyramide

Note: This page contains side effects data for the generic drug disopyramide. It is possible that some of the dosage forms included below may not apply to the brand name Norpace CR.

For the Consumer

Applies to disopyramide: oral capsule, oral capsule extended release, oral tablet extended release

As well as its needed effects, disopyramide (the active ingredient contained in Norpace CR) may cause unwanted side effects that require medical attention.

Severity: Moderate

If any of the following side effects occur while taking disopyramide, check with your doctor or nurse as soon as possible:

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
  • Enlargement of breasts in men
  • fever
  • mental depression
  • nosebleeds or bleeding gums
  • sore throat and fever
  • yellow eyes or skin
Signs and symptoms of hypoglycemia (low blood sugar)
  • Anxious feeling
  • chills
  • cold sweats
  • confusion
  • cool, pale skin
  • drowsiness
  • fast heartbeat
  • headache
  • hunger (excessive)
  • nausea
  • nervousness
  • shakiness
  • unsteady walk
  • unusual tiredness or weakness

Minor Side Effects

Some disopyramide side effects may not need any medical attention. As your body gets used to the medicine these side effects may disappear. Your health care professional may be able to help you prevent or reduce these side effects, but do check with them if any of the following side effects continue, or if you are concerned 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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It is possible that some side effects of Norpace CR may not have been reported. These can be reported to the FDA here. Always consult a healthcare professional for medical advice.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.