Norpace (Disopyramide) - Oral: Uses, Side Effects, Dosages (2023)

What Is Norpace?

Norpace (disopyramide) is an orally administered prescription medication used to treat life-threatening abnormal heart rhythm problems in adults 18 and older.

Norpace contains the active drug, disopyramide, which belongs to the antiarrhythmic 1A drugs class.

The antiarrhythmic 1A drugs class refers to a grouping of drugs defined as sodium channel blockers that block fast sodium channels, therefore slowing conduction in fast-channel tissues.

Most antiarrhythmic drugs are grouped into four main classes, and it's important to know that these class I drugs are subdivided based on the specific kinetics (the rate of reaction) of their sodium channel effects.

Norpace works by blocking the electrical signals in the heart that causes abnormal heartbeats, making your heart more resistant to abnormal activity.

Containing the primary ingredient disopyramide, Norpace is a prescription drug available in the form of immediate-release (IR) tablets called Norpace, and extended-release (ER) capsules, under the brand name Norpace CR. Disopyramide is also available as a generic product administered via IR tablets.

This article will highlight both the orally administered IR tablets of Norpace and the ER capsule of Norpace CR.

For context, ER capsules slowly release the drug to work for a longer duration while IR capsules instantaneously disintegrate to make the drug immediately available for absorption.

Drug Facts

Generic Name:Disopyramide

Brand Name(s):Norpace, Norpace CR

Drug Availability: Prescription

Therapeutic Classification: Antiarrhythmic 1A

Available Generically:Yes

Controlled Substance:N/A

Administration Route:Oral

Active Ingredient:Disopyramide phosphate

Dosage Form(s):IR tablets, ER capsules

What Is Norpace Used For?

The FDA has approved Norpace for the treatment of documented and life-threatening ventricular arrhythmias, such as sustained ventricular tachycardia (ventricular rhythm faster than 100 beats per minute lasting at least 30 seconds).

Ventricular arrhythmias areabnormal heartbeats that originate in your lower heart chambers, called ventricles. Abnormal heartbeats often manifest themselves in the form of a heartbeat that beats too quickly (tachycardia) or a heart that beats too slowly (bradycardia).

There are limitations associated with the use of Norpace, including:

  • Use of Norpace is not recommended in lesser arrhythmias.
  • Avoid use in people with asymptomatic ventricular premature contractions.
  • Initiation of treatment with Norpace to treat life-threatening arrhythmias should be carried out in a hospital setting.
  • Don't use Norpace initially if rapid plasma levels of the drug are required.
  • Antiarrhythmic drugs do not enhance the survival rate in ventricular arrhythmias.

How to Take Norpace

Read the information leaflet before taking medicine.

Ask your healthcare provider if you have questions or don't understand any of the following:

  • Norpace is available as IR tablets and ER capsules.
  • Take the IR tablets every six to eight hours or as prescribed.
  • Take ER capsules every 12 hours or as prescribed.
  • Swallow the ER capsule whole. Don't break, open, or crush the capsules.
  • Take the medicine as prescribed.
  • Norpace controls but does not cure ventricular arrhythmias.
  • Don't stop taking it without talking to your healthcare provider, even if your condition improves.


Store at 77 degrees F. Keep your medications tightly closed and out of the reach of children and pets, ideally locked in a cabinet or closet. Do not store your medication in the bathroom.

Avoid pouring unused and expired drugs down the drain or in the toilet. Ask your pharmacist or healthcare provider about the best ways to dispose of this medicine.

Visit the FDA's website to know where and how to discard all unused and expired drugs. You can also find disposal boxes in your area. Ask your pharmacist or healthcare provider if you have any questions about the best ways to dispose of your medications.

If you travel with Norpace, get familiar with your final destination's regulations. In general, be sure to make a copy of your Norpace prescription.

Keep your medication in its original container from your pharmacy with your name on the label. Ask your healthcare provider if you have any questions about traveling with your medicine.

Off-Label Uses

Disopyramide has been used in the treatment of hypertrophic cardiomyopathy (HCM). HCM is a relatively common condition in which the heart muscle becomes thick and unable to pump blood normally.

How Long Does Norpace Take to Work?

Norpace is rapidly and almost completely absorbed after oral intake and reaches its peak plasma levels (when the drug is most concentrated in the bloodstream) in about two hours. However, depending on whether you take IR tablets or ER capsules, the time of impact and absorption will vary.

What Are the Side Effects of Norpace?

This is not a complete list of side effects, and others may occur. A healthcare provider can advise you on side effects. If you experience other effects, contact your pharmacist or a healthcare provider. You may report side effects to the FDA at or 800-FDA-1088.

Common Side Effects

Common side effects of Norpace include:

  • Blurred vision
  • Constipation
  • Difficult urination
  • Dizziness or lightheadedness
  • Dry mouth
  • Fatigue
  • Frequent urination
  • Headache
  • Nausea
  • Rash
  • Stomach pain or bloating
  • Weakness

Call your healthcare provider if your symptoms worsen.

Severe Side Effects

The FDA has issued a boxed warning for Norpace. Boxed warnings are the agency’s strongest warnings for serious and potentially life-threatening risks.

The boxed warning:

Taking antiarrhythmic drugs such as Norpace may increase the risk of death. Tell your healthcare provider if you experience any heart disease such as a valve problem or heart failure.

In case of symptoms such as irregular heartbeat or chest pain, call your healthcare provider. Norpace may increase the chance of having arrhythmias. Don't use Norpace in people without life-threatening arrhythmias.

Contact your healthcare provider immediately if you develop any signs of a severe reaction. Call 911 if your symptoms feel life-threatening.

Serious side effects and their symptoms include:

  • Angina (chest pain)
  • Cardiac arrhythmias
  • Shortness of breath
  • Sudden changes in mental status
  • Edema (swelling of the feet, hands, or other parts of the body)
  • Unusual weight gain

Report Side Effects

Norpace may cause other side effects. Call your healthcare provider if you have unusual problems while taking this medication.

If you experience a serious side effect, you or your provider may send a report to the FDA's MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

(800) 332-1088

Dosage: How Much Norpace Should I Take?

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The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For heart rhythm problems:
    • For oral dosage form (capsules):
      • Adults—400 to 800 milligrams (mg) per day given in divided doses. Dose is usually 600 mg per day given in divided doses (150 mg every 6 hours). Your doctor may adjust your dose as needed.
      • Adults weighing less than 50 kilograms (kg)—Dose is usually 400 mg per day given in divided doses (100 mg every 6 hours). Your doctor may adjust your dose as needed.
      • Children—Use and dose must be determined by your doctor.
    • For oral dosage forms (extended-release capsules):
      • Adults—400 to 800 milligrams (mg) per day given in divided doses. Dose is usually 600 milligrams (mg) per day given in divided doses (300 mg every 12 hours). Your doctor may adjust your dose as needed.
      • Adults weighing less than 50 kilograms (kg)—Dose is usually 400 mg per day given in divided doses (200 mg every 12 hours). Your doctor may adjust your dose as needed.
      • Children—Use and dose must be determined by your doctor.


The following modifications (changes) should be kept in mind when using Norpace:

Severe allergic reaction: Avoid using Norpace if you have a known allergy to it or its ingredients. Ask your pharmacist or healthcare provider for a complete list of the ingredients if you're unsure.

Pregnancy: We don't know enough about the safety and effectiveness of Norpace in pregnant people and the unborn fetus. Discuss with your healthcare provider if you plan to become pregnant or are pregnant, and weigh the benefits and risks of taking Norpace during your pregnancy.

Breastfeeding: The metabolites of Norpace are present in human breast milk. Talk with your healthcare provider if you plan to breastfeed, to weigh the benefits and risks of taking Norpace while nursing and the different ways to feed your baby.

Adults over 65: Clinical studies haven't included a large enough number of people in this age group to see whether they respond differently from younger adults. Older adults with several medical conditions or taking several medications should use Norpace cautiously.

The dose selection should be toward the lower dosing end, attributing to decreased renal and hepatic functions. Older adults might also be more sensitive to Norpace side effects.

Children: The safety and effectiveness of Norpace have not been established in children.

Other modifications: The kidney excretes Norpace, and the risk of toxic reactions to this drug may be greater in people with impaired renal function. Carefully select the dose and monitor renal function.

Missed Dose

If you accidentally forgot your Norpace dose, take it as soon as you remember.

If it's already close to your next scheduled dose, skip the missed dose and take the following dose at your next scheduled dosing time. Don't try to double up to make up for the missed dose.

Try to find ways that work for you to help yourself remember to routinely keep your appointments and take your medication. If you miss too many doses, Norpace might be less effective at preventing your condition.

Overdose: What Happens If I Take Too Much Norpace?

If you think that you're experiencing an overdose or life-threatening symptoms, however, seek immediate medical attention.

The symptoms of a suspected overdose of Norpace include:

  • Constipation
  • Difficulty urinating
  • Dry mouth
  • Loss of consciousness
  • Slow or irregular heartbeat

What Happens If I Overdose on Norpace?

If you think you or someone else may have overdosed on Norpace, call a healthcare provider or the Poison Control Center (800-222-1222).

If someone collapses or isn't breathing after taking Norpace, call 911 immediately.


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It is very important that your doctor check your progress at regular visitsto make sure this medicine is working properly. Blood tests may be needed to check for unwanted effects.

Disopyramide may worsen the symptoms of heart failure in some patients. Check with your doctor right away if you are having chest pain or discomfort, dilated neck veins, extreme fatigue, irregular breathing or heartbeat, swelling of the face, fingers, feet, or lower legs, trouble breathing, or weight gain.

Contact your doctor right away if you have any changes to your heart rhythm. You might feel dizzy or faint, or you might have a fast, pounding, or uneven heartbeat. Make sure your doctor knows if you or anyone in your family has ever had a heart rhythm problem such as QT prolongation.

Do not suddenly stop taking this medicine without first checking with your doctor. Your doctor may want you to gradually reduce the amount you are taking before stopping it completely. Some conditions may become worse when the medicine is stopped suddenly, which can be dangerous.

This medicine may cause changes in your blood sugar levels. Also, this medicine may cover up signs of low blood sugar, such as a rapid pulse rate. Check with your doctor if you have these problems or if you notice a change in the results of your blood or urine sugar tests.

Dizziness, lightheadedness, or even fainting may occur when you get up suddenly from a lying or sitting position. Getting up slowly may help lessen this problem. Also, lying down for a while may relieve the dizziness or lightheadedness.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

What Are Reasons I Shouldn’t Take Norpace?

Norpace is not encouraged for those with the following conditions:

  • Cardiogenic shock
  • Preexisting second- or third-degree AV block (in the absence of a pacemaker)
  • Congenital Q-T prolongation
  • Hypersensitivity to Norpace or its primary ingredients
  • Myasthenia gravis (severe muscular weakness)
  • Glaucoma
  • Urinary retention

What Other Medications May Interact With Norpace?

Use caution when taking Norpace with the following medications:

  • Biaxin XL (clarithromycin): Antibacterial medication
  • Ery-Tab (erythromycin): Antibacterial medication
  • Dilantin (phenytoin): Seizure prevention medication
  • Inderal LA (propranolol): Hypertension (high blood pressure) medication
  • Verelan (verapamil): Hypertension and angina (chest pain) medication

Your healthcare provider may need to adjust the dose of these drugs when used with Norpace.

And be sure to talk with your healthcare provider about any other medicines you take or plan to take, including over-the-counter (OTC), nonprescription products, vitamins, herbs, or plant-based medicines.

What Medications Are Similar?

Other drugs that work similarly to Norpace (medications used to treat ventricular arrhythmias) and that are also classified as 1A antiarrhythmic drugs include:

  • Pronestyl (procainamide)
  • Nuedexta (dextromethorphan and quinidine)
  • Pacerone (amiodarone)

Frequently Asked Questions

  • What is Norpace?

    Norpace is an antiarrhythmic drug used to treat life-threatening irregular heartbeats. It contains the active drug, disopyramide, which belongs to the antiarrhythmic 1A drugs class.

    Learn More:Medications Used to Treat Cardiac Arrhythmias

  • How does Norpace work?

    Norpace works by blocking the electrical signals in the heart that causes abnormal heartbeats, therefore, making your heart more resistant to abnormal activity.

  • Can I take Norpace while I am pregnant or breastfeeding?

    There is not enough data available about the use of Norpace in pregnant and breastfeeding people. Ask your healthcare provider if you are pregnant or breastfeeding before using this drug.

    The drug should only be used if the benefit outweighs the risk.

How Can I Stay Healthy While Taking Norpace?

Heart arrhythmias can be a life-threatening condition and can negatively affect your quality of life.

As such, you may have tried different approaches or treatments. However, when prescribed Norpace, refer below for some specific tips on how to support your health while taking the medication:

  • Take your medications as recommended by your healthcare provider.
  • Don't skip the doses.
  • Achieve a healthy lifestyle to prevent the worsening of heart rhythm.
  • Consider working with a registered health practitioner to help you identify and manage your condition.
  • Talk to your healthcare provider before taking Norpace; if you become pregnant or breastfeeding.
  • Don't discontinue taking your medicine without asking your healthcare provider, even if you feel better.
  • Keep a close check on your symptoms. In case of chest pain or irregular heartbeat, immediately contact your healthcare provider.

Medical Disclaimer

Verywell Health's drug information is meant for educational purposes only and is not intended as a replacement for medical advice, diagnosis, or treatment from a healthcare provider. Consult your healthcare provider before taking any new medication(s). IBM Watson Micromedexprovides some of the drug content, as indicated on the page.

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