Disopyramide 150mg Capsules
WARNING: This drug is only to be used to treat certain types of abnormal heartbeats. Other abnormal heartbeats have happened with this drug, which in rare cases can be deadly. Talk to the doctor if you have any questions about this drug. @ COMMON USES: It is used to treat certain types of abnormal heartbeats.It may be given to you for other reasons. Talk with the doctor.
Drug Class
Antiarrhythmic
Pharmacologic Class
Class IA Antiarrhythmic
Pregnancy Category
C
FDA Approved
Jan 1977
DEA Schedule
Not Controlled
Overview
What is this medicine?
Disopyramide is a medication used to treat certain types of irregular heartbeats (arrhythmias). It works by helping to stabilize the electrical activity in your heart, which can prevent or stop abnormal rhythms. It's often used for serious, life-threatening heart rhythm problems.
How to Use This Medicine
Taking Your Medication Correctly
To get the most benefit from your medication, it's essential to take it exactly as directed by your doctor. Carefully read all the information provided with your prescription, and follow the instructions closely. Continue taking your medication as prescribed by your doctor or healthcare provider, even if you start to feel better.
If you have difficulty swallowing pills, your doctor or pharmacist can help you prepare a liquid suspension. If a liquid suspension is prepared, make sure to shake it well before each use. To ensure accurate dosing, measure the liquid carefully using the measuring device provided with your medication. If no device is included, ask your pharmacist for a suitable measuring tool.
Storing and Disposing of Your Medication
To maintain the effectiveness and safety of your medication, store it at room temperature in a dry place, away from the bathroom. If a liquid suspension is prepared, store it in the refrigerator, but do not freeze. Discard any unused portion of the liquid suspension after 30 days.
Keep all medications in a secure location, out of the reach of children and pets, to prevent accidental ingestion or exposure.
What to Do If You Miss a Dose
If you miss a dose, take it as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at the same time or take extra doses to make up for the missed one.
To get the most benefit from your medication, it's essential to take it exactly as directed by your doctor. Carefully read all the information provided with your prescription, and follow the instructions closely. Continue taking your medication as prescribed by your doctor or healthcare provider, even if you start to feel better.
If you have difficulty swallowing pills, your doctor or pharmacist can help you prepare a liquid suspension. If a liquid suspension is prepared, make sure to shake it well before each use. To ensure accurate dosing, measure the liquid carefully using the measuring device provided with your medication. If no device is included, ask your pharmacist for a suitable measuring tool.
Storing and Disposing of Your Medication
To maintain the effectiveness and safety of your medication, store it at room temperature in a dry place, away from the bathroom. If a liquid suspension is prepared, store it in the refrigerator, but do not freeze. Discard any unused portion of the liquid suspension after 30 days.
Keep all medications in a secure location, out of the reach of children and pets, to prevent accidental ingestion or exposure.
What to Do If You Miss a Dose
If you miss a dose, take it as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at the same time or take extra doses to make up for the missed one.
Lifestyle & Tips
- Take exactly as prescribed, do not skip doses or take extra.
- Do not crush, chew, or break extended-release capsules.
- Report any new or worsening symptoms to your doctor immediately.
- Avoid alcohol, as it can worsen side effects or affect heart rhythm.
- Maintain good hydration to help prevent anticholinergic side effects like dry mouth and constipation.
- Be aware of potential dizziness or blurred vision, especially when starting the medication, and avoid driving or operating machinery until you know how it affects you.
Available Forms & Alternatives
Available Strengths:
Dosing & Administration
Adult Dosing
Standard Dose:
150 mg every 6 hours (immediate release) or 300 mg every 12 hours (extended release)
Dose Range:
100 - 400 mg
Condition-Specific Dosing:
initialLoadingDose:
300 mg (immediate release) for rapid control of ventricular arrhythmias, followed by maintenance.
cardiomyopathyOrCardiacDecompensation:
Initial dose 100 mg every 6 hours (immediate release) or 200 mg every 12 hours (extended release).
Pediatric Dosing
Neonatal:
Not established
Infant:
Not established
Child:
Not established
Adolescent:
Not established
Dose Adjustments
Renal Impairment:
Mild:
CrCl 40-60 mL/min: 100 mg every 8 hours (immediate release) or 200 mg every 12 hours (extended release).
Moderate:
CrCl 20-40 mL/min: 100 mg every 10 hours (immediate release) or 150 mg every 12 hours (extended release).
Severe:
CrCl <20 mL/min: 100 mg every 14 hours (immediate release) or 100 mg every 12 hours (extended release).
Dialysis:
Administer dose after dialysis. Supplemental dose may be needed.
Hepatic Impairment:
Mild:
No specific adjustment, monitor closely.
Moderate:
Reduce dose by approximately 25-50% (e.g., 100 mg every 6 hours for immediate release).
Severe:
Reduce dose by approximately 50% or more (e.g., 100 mg every 8-12 hours for immediate release).
Pharmacology
Mechanism of Action
Disopyramide is a Class IA antiarrhythmic agent. It decreases the rate of depolarization (phase 0) and prolongs the action potential duration and effective refractory period in atrial and ventricular myocardial fibers and accessory bypass tracts. This is primarily achieved by blocking fast sodium channels, thereby reducing the maximum rate of depolarization (Vmax) and increasing the threshold for excitability. It also possesses anticholinergic properties.
Pharmacokinetics
Absorption:
Bioavailability:
80-90%
Tmax:
0.5-3 hours (immediate release)
FoodEffect:
Food may delay absorption but does not significantly affect the extent of absorption.
Distribution:
Vd:
0.8-1.2 L/kg
ProteinBinding:
50-65% (concentration-dependent, decreases with higher concentrations)
CnssPenetration:
Limited
Elimination:
HalfLife:
4-10 hours (immediate release), 10-18 hours (extended release)
Clearance:
Not available
ExcretionRoute:
Renal (50-60% unchanged), Hepatic (10-20% as MND)
Unchanged:
50-60%
Pharmacodynamics
OnsetOfAction:
Within 30 minutes to 2 hours
PeakEffect:
1-3 hours
DurationOfAction:
6-12 hours (immediate release), 12-24 hours (extended release)
Safety & Warnings
BLACK BOX WARNING
Disopyramide has a narrow therapeutic index and can cause significant adverse effects, including proarrhythmia (aggravation or induction of new arrhythmias, including ventricular tachycardia and fibrillation, and Torsades de Pointes), and negative inotropic effects (worsening of heart failure). It should be reserved for patients with life-threatening ventricular arrhythmias because of its proarrhythmic potential. Patients should be hospitalized for initiation of therapy.
Side Effects
Serious Side Effects: Seek Medical Help Right Away
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you experience any of the following symptoms, contact your doctor or seek medical attention immediately:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Signs of low blood sugar, including:
+ Dizziness
+ Headache
+ Feeling sleepy
+ Feeling weak
+ Shaking
+ Fast heartbeat
+ Confusion
+ Hunger
+ Sweating
New or worsening abnormal heartbeat
Chest pain or pressure
Changes in eyesight
Trouble passing urine, frequent urination, or urgent need to urinate
Muscle weakness
A type of abnormal heartbeat (prolonged QT interval) has been associated with this medication, which can increase the risk of another type of abnormal heartbeat (torsades de pointes). If you experience a fast or abnormal heartbeat, or if you pass out, seek medical help immediately.
Heart failure has been reported with this medication, and it can worsen existing heart failure. If you have a history of heart disease, inform your doctor. Seek medical attention immediately if you experience:
+ Shortness of breath
+ Sudden weight gain
+ Abnormal heartbeat
+ New or worsening swelling in the arms or legs
Other Possible Side Effects
Like all medications, this drug can cause side effects. While many people may not experience any side effects or only minor ones, it's essential to discuss any concerns with your doctor. If you experience any of the following side effects, or if they persist or bother you, contact your doctor:
Headache
Constipation
Dry mouth, nose, or throat
Dry eyes
Dizziness
Fatigue
Weakness
Bloating
Gas
Upset stomach
Stomach pain
This is not an exhaustive list of possible side effects. If you have questions or concerns about side effects, consult your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you experience any of the following symptoms, contact your doctor or seek medical attention immediately:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Signs of low blood sugar, including:
+ Dizziness
+ Headache
+ Feeling sleepy
+ Feeling weak
+ Shaking
+ Fast heartbeat
+ Confusion
+ Hunger
+ Sweating
New or worsening abnormal heartbeat
Chest pain or pressure
Changes in eyesight
Trouble passing urine, frequent urination, or urgent need to urinate
Muscle weakness
A type of abnormal heartbeat (prolonged QT interval) has been associated with this medication, which can increase the risk of another type of abnormal heartbeat (torsades de pointes). If you experience a fast or abnormal heartbeat, or if you pass out, seek medical help immediately.
Heart failure has been reported with this medication, and it can worsen existing heart failure. If you have a history of heart disease, inform your doctor. Seek medical attention immediately if you experience:
+ Shortness of breath
+ Sudden weight gain
+ Abnormal heartbeat
+ New or worsening swelling in the arms or legs
Other Possible Side Effects
Like all medications, this drug can cause side effects. While many people may not experience any side effects or only minor ones, it's essential to discuss any concerns with your doctor. If you experience any of the following side effects, or if they persist or bother you, contact your doctor:
Headache
Constipation
Dry mouth, nose, or throat
Dry eyes
Dizziness
Fatigue
Weakness
Bloating
Gas
Upset stomach
Stomach pain
This is not an exhaustive list of possible side effects. If you have questions or concerns about side effects, consult your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Seek Immediate Medical Attention If You Experience:
- New or worsening palpitations or irregular heartbeats
- Dizziness, lightheadedness, or fainting spells
- Shortness of breath, swelling in ankles/feet, or sudden weight gain (signs of heart failure)
- Blurred vision or difficulty seeing
- Difficulty urinating or inability to urinate
- Severe dry mouth or constipation
- Chest pain
Before Using This Medicine
Before Taking This Medication: Important Information to Share with Your Doctor
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the allergic reaction you experienced, including any symptoms that occurred.
Certain health conditions, including:
+ Heart problems, such as heart block without a functioning pacemaker, heart failure, a prolonged QT interval on an electrocardiogram (ECG), or low blood pressure.
+ Glaucoma or myasthenia gravis.
+ Difficulty urinating.
+ Kidney disease.
+ Abnormal potassium levels, either high or low.
+ Recent use of verapamil (within the past 24 hours).
This medication can interact with numerous other drugs, which may increase the risk of severe, life-threatening, or fatal side effects. Therefore, it is crucial to discuss the following with your doctor and pharmacist:
All prescription and over-the-counter (OTC) medications you are taking.
Any natural products or vitamins you are using.
* Your complete medical history, including all health problems.
Before starting, stopping, or changing the dose of any medication, including this one, you must consult with your doctor to ensure your safety. It is your responsibility to verify that it is safe to take this medication with all your other medications and health conditions.
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the allergic reaction you experienced, including any symptoms that occurred.
Certain health conditions, including:
+ Heart problems, such as heart block without a functioning pacemaker, heart failure, a prolonged QT interval on an electrocardiogram (ECG), or low blood pressure.
+ Glaucoma or myasthenia gravis.
+ Difficulty urinating.
+ Kidney disease.
+ Abnormal potassium levels, either high or low.
+ Recent use of verapamil (within the past 24 hours).
This medication can interact with numerous other drugs, which may increase the risk of severe, life-threatening, or fatal side effects. Therefore, it is crucial to discuss the following with your doctor and pharmacist:
All prescription and over-the-counter (OTC) medications you are taking.
Any natural products or vitamins you are using.
* Your complete medical history, including all health problems.
Before starting, stopping, or changing the dose of any medication, including this one, you must consult with your doctor to ensure your safety. It is your responsibility to verify that it is safe to take this medication with all your other medications and health conditions.
Precautions & Cautions
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication. In some cases, your doctor may recommend that you start taking this drug in a hospital setting where your condition can be closely monitored.
If you have diabetes, it is crucial to closely monitor your blood sugar levels while taking this medication. Additionally, you should discuss your alcohol consumption with your doctor before drinking.
As you age, your sensitivity to certain medications may increase. If you are 65 years or older, use this drug with caution, as you may be more prone to experiencing side effects.
If you are pregnant, planning to become pregnant, or are breastfeeding, it is vital to consult with your doctor to discuss the potential benefits and risks of this medication to both you and your baby.
If you have diabetes, it is crucial to closely monitor your blood sugar levels while taking this medication. Additionally, you should discuss your alcohol consumption with your doctor before drinking.
As you age, your sensitivity to certain medications may increase. If you are 65 years or older, use this drug with caution, as you may be more prone to experiencing side effects.
If you are pregnant, planning to become pregnant, or are breastfeeding, it is vital to consult with your doctor to discuss the potential benefits and risks of this medication to both you and your baby.
Overdose Information
Overdose Symptoms:
- Severe hypotension (very low blood pressure)
- Widening of the QRS complex on ECG
- Prolonged QT interval
- AV block (heart block)
- Asystole (cardiac arrest)
- Respiratory depression
- Loss of consciousness
- Anticholinergic effects (severe dry mouth, dilated pupils, urinary retention)
What to Do:
Seek immediate medical attention. Call 911 or your local emergency number. For poison control, call 1-800-222-1222.
Drug Interactions
Contraindicated Interactions
- Pre-existing second- or third-degree AV block (unless pacemaker is present)
- Cardiogenic shock
- Known hypersensitivity to disopyramide
- Congenital long QT syndrome (relative contraindication due to proarrhythmic risk)
- Severe heart failure (unless arrhythmia is life-threatening and other options failed)
Major Interactions
- Other Class IA antiarrhythmics (e.g., quinidine, procainamide) - increased proarrhythmic risk
- Class IC antiarrhythmics (e.g., flecainide, propafenone) - increased proarrhythmic risk
- Amiodarone - increased disopyramide levels, increased QT prolongation
- Beta-blockers (especially IV) - increased negative inotropic effects, bradycardia
- Calcium channel blockers (non-dihydropyridine, e.g., verapamil, diltiazem) - increased negative inotropic effects, bradycardia, AV block
- Drugs that prolong QT interval (e.g., antipsychotics, macrolide antibiotics, fluoroquinolones, tricyclic antidepressants) - increased risk of Torsades de Pointes
- CYP3A4 inhibitors (e.g., ketoconazole, ritonavir, clarithromycin) - increased disopyramide levels
- CYP3A4 inducers (e.g., rifampin, phenytoin, carbamazepine) - decreased disopyramide levels
Moderate Interactions
- Anticholinergic drugs (e.g., atropine, tricyclic antidepressants, antihistamines) - additive anticholinergic effects (e.g., urinary retention, blurred vision)
- Diuretics (especially loop or thiazide) - may cause electrolyte disturbances (hypokalemia, hypomagnesemia) increasing proarrhythmic risk
- Digoxin - may increase digoxin levels (minor effect), monitor digoxin levels
Minor Interactions
- Antacids - may affect absorption (separate administration)
Monitoring
Baseline Monitoring
Electrocardiogram (ECG)
Rationale: Assess baseline rhythm, PR, QRS, and QTc intervals; identify pre-existing conduction abnormalities or prolonged QT.
Timing: Prior to initiation
Serum Electrolytes (Potassium, Magnesium)
Rationale: Correct hypokalemia or hypomagnesemia prior to therapy to reduce proarrhythmic risk.
Timing: Prior to initiation
Renal Function (CrCl)
Rationale: Disopyramide is primarily renally excreted; dose adjustment is necessary in renal impairment.
Timing: Prior to initiation
Hepatic Function (LFTs)
Rationale: Disopyramide is metabolized by the liver; dose adjustment may be necessary in hepatic impairment.
Timing: Prior to initiation
Blood Pressure and Heart Rate
Rationale: Establish baseline and monitor for hypotensive or bradycardic effects.
Timing: Prior to initiation
Echocardiogram/Cardiac Function Assessment
Rationale: Assess left ventricular function due to negative inotropic effects.
Timing: Prior to initiation, especially in patients with heart disease
Routine Monitoring
Electrocardiogram (ECG) - QTc interval
Frequency: Daily during initiation/dose titration, then periodically (e.g., weekly, monthly) or with dose changes.
Target: <450 ms (men), <470 ms (women); avoid >500 ms or >25% increase from baseline.
Action Threshold: If QTc prolongs significantly (>500 ms or >25% increase), consider dose reduction or discontinuation. If QRS widens by >25%, consider dose reduction.
Serum Disopyramide Levels (if available/indicated)
Frequency: After 2-3 days of stable dosing, then periodically or if toxicity/lack of efficacy suspected.
Target: Therapeutic range: 2-5 mcg/mL (for ventricular arrhythmias).
Action Threshold: Levels >7 mcg/mL associated with increased toxicity; adjust dose to maintain therapeutic range.
Serum Electrolytes (Potassium, Magnesium)
Frequency: Periodically, especially if on diuretics or with GI losses.
Target: Normal range (K+ 3.5-5.0 mEq/L, Mg 1.7-2.2 mg/dL).
Action Threshold: Correct hypokalemia/hypomagnesemia promptly.
Renal Function (CrCl)
Frequency: Periodically, especially in elderly or those with changing renal function.
Target: Not applicable.
Action Threshold: Adjust dose if renal function declines.
Blood Pressure and Heart Rate
Frequency: Regularly, especially during initiation.
Target: Maintain within patient's normal range.
Action Threshold: Significant hypotension or bradycardia may require dose adjustment.
Symptom Monitoring
- New or worsening arrhythmias (palpitations, dizziness, syncope)
- Symptoms of heart failure (shortness of breath, edema, weight gain)
- Anticholinergic effects (dry mouth, blurred vision, urinary retention, constipation)
- Signs of overdose (hypotension, widening QRS, prolonged QT, AV block, asystole, respiratory depression)
Special Patient Groups
Pregnancy
Category C. Use only if the potential benefit justifies the potential risk to the fetus. Disopyramide has been shown to have embryocidal effects in animal studies at doses higher than human therapeutic doses. It can also cause uterine contractions.
Trimester-Specific Risks:
First Trimester:
Potential for embryocidal effects observed in animals; human data limited.
Second Trimester:
Risk of uterine contractions; monitor for fetal arrhythmias.
Third Trimester:
Risk of uterine contractions; monitor for fetal arrhythmias.
Lactation
Disopyramide is excreted into breast milk. Due to potential for serious adverse effects in the infant (e.g., arrhythmias, anticholinergic effects), a decision should be made whether to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother.
Infant Risk:
L3 (Moderate risk) - Potential for infant arrhythmias, anticholinergic effects (e.g., dry mouth, constipation, urinary retention), and growth suppression. Monitor infant for adverse effects.
Pediatric Use
Safety and effectiveness in pediatric patients have not been established. Use is generally not recommended due to lack of data and potential for serious adverse effects.
Geriatric Use
Elderly patients may be more sensitive to the effects of disopyramide, particularly its anticholinergic and negative inotropic effects. They are also more likely to have impaired renal function, requiring dose adjustments. Start with lower doses and titrate carefully, monitoring for adverse effects and drug levels.
Clinical Information
Clinical Pearls
- Disopyramide has significant negative inotropic effects and should be used with extreme caution, or avoided, in patients with pre-existing heart failure or significant left ventricular dysfunction.
- Its potent anticholinergic effects can be problematic, especially in elderly men with prostatic hypertrophy (risk of urinary retention) or patients with glaucoma (risk of acute angle-closure glaucoma).
- Hypokalemia and hypomagnesemia must be corrected prior to and during disopyramide therapy to minimize proarrhythmic risk.
- Due to its narrow therapeutic index and potential for serious adverse effects, initiation of disopyramide therapy typically requires hospitalization with continuous ECG monitoring.
- Disopyramide is often considered for patients with hypertrophic cardiomyopathy (HCM) to reduce left ventricular outflow tract obstruction due to its negative inotropic effects, though this is an off-label use in some regions.
Alternative Therapies
- Flecainide (Class IC antiarrhythmic)
- Propafenone (Class IC antiarrhythmic)
- Amiodarone (Class III antiarrhythmic)
- Sotalol (Class III antiarrhythmic, also beta-blocker)
- Dofetilide (Class III antiarrhythmic)
- Catheter ablation (non-pharmacological)
Cost & Coverage
Average Cost:
Varies widely, typically $30-$150 per 30 capsules (150mg)
Generic Available:
Yes
Insurance Coverage:
Tier 1 or Tier 2 (generic)
General Drug Facts
If your symptoms or health issues persist or worsen, it's essential to contact your doctor for further guidance. To ensure your safety, never share your medication with others or take someone else's medication. Some medications may come with an additional patient information leaflet, so be sure to check with your pharmacist for more information. If you have any questions or concerns about your medication, don't hesitate to reach out to your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek medical attention. When seeking help, be prepared to provide details about the medication taken, the amount, and the time it happened.