How does this medication work? What will it do for me?

Disopyramide belongs to the class of medications called antiarrhythmics. It is used to treat abnormal heart rhythms. It works in various areas of the heart to help normalize abnormal heart rhythms.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. As well, some forms of this medication may not be used for all of the conditions discussed here. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

What form(s) does this medication come in?

Rythmodan is no longer being manufactured for sale in Canada and is no longer available under any brand names. This article is being kept available for reference purposes only. If you are using this medication, speak with your doctor or pharmacist for information about your treatment options. Rythmodan may be available through the Special Access Drug Program. Contact your doctor or pharmacist for more information.

How should I use this medication?

The dose of disopyramide is individualized for each person, depending on the person's weight and response to the medication. The usual dose of disopyramide capsules is 100 mg to 200 mg every 6 hours. In certain circumstances, the doctor may start with a higher dose for the first dose only. People with reduced kidney or liver function may need lower daily doses.

Many things can affect the dose of a medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important to take this medication exactly as prescribed by your doctor. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature and keep it out of the reach of children.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Disopyramide should not be taken by anyone who:

  • is allergic to disopyramide or to any of the ingredients of the medication
  • is taking other medications to treat abnormal heart rhythms or medications that may cause abnormal heart rhythms (e.g., amiodarone, quinidine, sotalol, verapamil, diltiazem, pimozide)
  • is under 18 years old
  • has cardiomyopathy (a disease of the heart muscle)
  • has certain severe heart rhythm disorders (i.e., bundle-branch block associated with first-degree AV block, double block, or second- and third-degree AV block with no pacemaker)
  • has extensive heart disease
  • has glaucoma
  • has kidney failure
  • has long QT
  • has severe or uncontrolled congestive heart failure
  • has severe sinus node (the heart's natural pacemaker) dysfunction
  • has severely reduced kidney or liver function
  • has shock
  • has urinary retention

What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent. The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

  • blurred vision
  • changes in taste
  • constipation
  • diarrhea
  • drowsiness
  • dry eyes
  • dry mouth, nose, or throat
  • gas
  • increased sweating
  • indigestion
  • loss of appetite
  • nausea

Although most of these side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

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

  • bluish lips
  • chest pain
  • dizziness
  • feeling faint or fainting
  • heartbeat that is much faster or slower than usual
  • increased sensitivity of the skin to the sun
  • lightheadedness
  • pounding heartbeat
  • rapid weight gain
  • rash or itching
  • shortness of breath
  • swelling of feet or lower legs
  • urination difficulties

Stop taking the medication and seek immediate medical attention if any of the following occur:

  • signs of a severe allergic reactions (e.g., hives, difficulty breathing, swelling of the mouth or throat)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for this medication?

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Abnormal heart rhythms: Certain medications used to treat abnormal heart rhythms, including disopyramide, can also cause new abnormal heart rhythms, some of which can be life-threatening. Treatment with disopyramide should be started in the hospital, where appropriate monitoring and treatment can be provided.

Glaucoma: Disopyramide may cause an increase in the pressure inside the eye and should not be used by people with glaucoma. If you have a family history of glaucoma, your doctor will monitor you closely while taking this medication.

Heart failure: Disopryamide can cause or worsen heart failure and should not be used by people with severe or untreated heart failure. If you have heart failure and are taking this medication, your doctor will monitor you closely during treatment. If you notice shortness of breath; weight gain; or swelling in the hands, feet, or lower legs while taking disopyramide, contact your doctor immediately.

Kidney or liver disease: People with reduced kidney or liver function may need a lower dose of disopyramide. Your doctor will monitor your closely while you are taking this medication. People with severely reduced kidney or liver function should not take this medication.

Low blood pressure: This medication may cause low blood pressure. If you experience dizziness, lightheadedness, or fainting while taking this medication, contact your doctor immediately.

Low blood sugar: Disopyramide can cause low blood sugar, especially for people with certain medical conditions (e.g., heart failure, treated diabetes, chronic malnutrition, liver disease, kidney disease) or who are taking certain medications (e.g., atenolol, propranolol, metoprolol). If you are at risk of experiencing low blood sugar while taking this medication, your doctor will monitor your blood sugar closely during treatment.

Myasthenia gravis: Disopyramide may make this condition worse. Talk to your doctor about whether any special monitoring is needed.

Reduced concentration: This medication may reduce the ability to concentrate and react. Do not drive or operate machinery until you know how this medication affects you.

Urine retention problems: Disopyramide may cause urine retention. If you experience any difficulties with urination while taking this medication, contact your doctor.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: This medication passes into breast milk. If this medication is essential, you should not breast-feed while taking it.

Children: The safety and effectiveness of using this medication have not been established for children.

What other drugs could interact with this medication?

There may be an interaction between disopyramide and any of the following:

  • alcohol
  • amphotericin B
  • anticholinergic medications (e.g., atropine)
  • "azole" antifungal medications (e.g., fluconazole, ketoconazole, itraconazole, voriconazole)
  • beta-blockers (e.g., atenolol, metoprolol, propranolol)
  • clarithromycin
  • corticosteroids (e.g., dexamethasone, prednisone, prednisolone)
  • cosyntropin
  • cyclosporine
  • diuretics (e.g., hydrochlorothiazide, indapamide, furosemide)
  • domperidone
  • erythromycin
  • fluoxetine
  • haloperidol
  • imatinib
  • isoniazid
  • medications for erectile dysfunction (e.g., sildenafil, tadalafil, vardenafil)
  • methadone
  • nefazodone
  • nicardipine
  • other medications used to treat abnormal heart rhythms (e.g., amiodarone, diltiazem, verapamil, quinidine, sotalol, quinidine)
  • phenobarbital
  • phenothiazine medications (e.g., chlorpromazine, prochloperazine)
  • phenytoin
  • pimozide
  • protease inhibitors (e.g., ritonavir, indinavir, saquinavir)
  • quinolone antibiotics (e.g., gatifloxacin, levofloxacin, moxifloxacin, norfloxacin)
  • rifampin
  • stimulant laxatives (e.g., sennosides A and B, bisacodyl)
  • telithromycin
  • theophylline
  • tricyclic antidepressants (e.g., amitriptyline, clomipramine, desipramine, doxepin, imipramine, maprotiline, nortriptyline)
  • warfarin

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

  • stop taking one of the medications,
  • change one of the medications to another,
  • change how you are taking one or both of the medications, or
  • leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.

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