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.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. 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.

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.

100 mg
Each green-and-yellow, hard gelatin capsule, marked "RY RL", contains disopyramide 100 mg. Nonmedicinal ingredients: cornstarch, magnesium stearate, pregelatinized starch, and talc; capsule body and head: FD&C Blue No. 2, gelatin, titanium dioxide, and yellow iron oxide.

Do not take this medication if you:

• are allergic to disopyramide or any ingredients of the medication
• are in shock
• are taking other medications to treat abnormal heart rhythms or medications that may cause abnormal heart rhythms (e.g., amiodarone, quinidine, sotalol, verapamil, diltiazem, pimozide)
• have cardiomyopathy (a disease of the heart muscle)
• have 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)
• have extensive heart disease or heart failure
• have glaucoma
• have kidney failure
• have long QT interval
• have severe or uncontrolled congestive heart failure
• have severe sinus node (the heart's natural pacemaker) dysfunction
• have urinary retention

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
• vomiting

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

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

• bluish lips
• chest pain
• dizziness or lightheadedness
• difficulty urinating
• feeling faint or fainting
• heartbeat that is much faster or slower than usual
• increased sensitivity of the skin to the sun
• pounding heartbeat
• rash or itching
• signs of heart failure (e.g., shortness of breath, fatigue, swelling in legs, ankles, feet, rapid weight gain
• symptoms of low blood sugar (e.g., cold sweat, cool pale skin, headache, fast heart beat, weakness)

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.

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.

Certain medications (e.g., sotalol, quinidine, thioridazine, chlorpromazine, pimozide, moxifloxacin, mefloquine, pentamidine, arsenic trioxide, tacrolimus) can increase the risk of a type of abnormal heart rhythm called QT prolongation, and should not be used in combination with disopyramide. If you are taking other medications, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

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: Disopyramide can cause or worsen heart failure because it can reduce the strength of the heart muscle's contraction. It 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 function: Decreased kidney function can cause disopyramide to build up in the body, causing side effects. If you have reduced kidney function or kidney disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Liver function: Liver disease or reduced liver function may cause this medication to build up in the body, causing side effects. If you have liver problems, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. Your doctor may want to test your liver function regularly with blood tests while you are taking 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: Myasthenia gravis is a condition that causes specific muscle weakness. Disopyramide may make the symptoms of myasthenia gravis worse. If you have myasthenia gravis, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and 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.

Urinary retention: Disopyramide may cause urinary retention. This is more likely to affect men with an enlarged prostate gland, however it can also affect women. 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 you are a breast-feeding mother and are taking disopyramide, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

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

Seniors: Seniors may experience memory problems and confusion when using this medication.

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

• acetylsalicylic acid (ASA)
• aclidinium
• alfuzosin
• amantadine
• androgens (e.g., testosterone)
• antiarrhythmic medications (e.g., amiodarone, flecainide, lidocaine, procainamide, propafenone, quinidine, sotalol)
• antihistamines (e.g., azelastine, bilastine, cetirizine, doxylamine, diphenhydramine, hydroxyzine, loratadine, rupatadine)
• antipsychotics (e.g., chlorpromazine, clozapine, haloperidol, olanzapine, quetiapine, risperidone)
• apomorphine
• aprepitant
• atomoxetine
• atropine
• "azole" antifungal medications (e.g., fluconazole, ketoconazole, itraconazole, voriconazole)
• benztropine
• beta 2 agonists (e.g., formoterol, indacaterol, salmeterol, terbutaline)
• beta-blockers (e.g., atenolol, metoprolol, propranolol)
• bismuth subsalicylate
• bosentan
• bromocriptine
• buprenorphine
• buserelin
• butorphanol
• calcium channel blockers (e.g., amlodipine, diltiazem, nifedipine, verapamil)
• cannabis
• capecitabine
• carbamazepine
• chloral hydrate
• clidinium
• cobicistat
• conivaptan
• corticosteroids (e.g., dexamethasone, hydrocortisone, prednisone)
• cyclobenzaprine
• cyclosporine
• darifenacin
• deferasirox
• diabetes medications (e.g., acarbose, canagliflozin, glyburide, insulin, linagliptin, lixisenatide, metformin,  rosiglitazone)
• dimenhydrinate
• diuretics (e.g., hydrochlorothiazide, indapamide, furosemide)
• domperidone
• donepezil
• dronedarone
• eliglustat
• enzalutamide
• fesoterodine
• galantamine
• glucagon
• glycopyrrolate
• grapefruit juice
• goserelin
• HIV non-nucleoside reverse transcriptase inhibitors (NNRTIs; e.g., efavirenz, etravirine, nevirapine, rilpivirine)
• HIV protease inhibitors (e.g., atazanavir, indinavir, ritonavir, saquinavir)
• hydroxychloroquine
• ipratropium
• ketotifen
• letermovir
• lithium
• linezolid
• loperamide
• macrolide antibiotics (e.g., azithromycin, clarithromycin, erythromycin)
• meclizine
• mefloquine
• methadone
• methotrimeprazine
• metoclopramide
• metronidazole
• mifepristone
• mirabegron
• mirtazapine
• mitotane
• modafinil
• monoamine oxidase inhibitors (MAOIs; e.g., moclobemide, phenelzine, rasagiline, selegiline, tranylcypromine)
• narcotic pain relievers (e.g., codeine, fentanyl, morphine, oxycodone, tapentadol, tramadol)
• nitroglycerin
• orphenadrine
• oxybutynin
• pegvisomant
• pentamidine
• phenobarbital
• phenytoin
• phosphodiesterase-5 inhibitors (e.g., sildenafil, tadalafil, vardenafil)
• primidone
• potassium chloride
• primaquine
• protein kinase inhibitors (e.g., bosutinib, crizotinib, dasatinib, imatinib, nilotinib, pazopanib)
• romidepsin
• quinolone antibiotics (e.g., levofloxacin, moxifloxacin, norfloxacin)
• rifabutin
• rifampin
• rivastigmine
• St. John's wort
• scopolamine
• selective serotonin reuptake inhibitors (SSRIs; e.g., citalopram, fluoxetine, paroxetine, sertraline)
• serotonin antagonists (anti-emetic medications; e.g., granisetron, ondansetron)
• solifenacin
• somatostatin-like medications (e.g., lanreotide, octreotide, pasireotide)
• sphingosine 1-phosphate receptor (S1P) receptor inhibitors (e.g., fingolimod, ponesimod, siponimod)
• sulfonamide antibiotics ("sulfas"; e.g., sulfisoxazole, sulfamethoxazole)
• tacrolimus
• tamoxifen
• tetrabenazine
• tiotropium
• tolterodine
• topiramate
• trazodone
• tricyclic antidepressants (e.g., amitriptyline, clomipramine, desipramine, imipramine, nortriptyline)
• trospium
• umeclidinium
• 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.