Disopyramide 100mg 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
Category C
FDA Approved
Jan 1977
DEA Schedule
Not Controlled
Overview
What is this medicine?
Disopyramide is a medication used to help your heart beat regularly. It works by affecting the electrical signals in your heart to control certain types of irregular heartbeats (arrhythmias). It's important to take it exactly as prescribed.
How to Use This Medicine
Taking Your Medication Correctly
To get the most benefit from your medication, 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 trouble 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. When measuring your liquid dose, use the measuring device that comes with your medication. If one is not provided, ask your pharmacist for a suitable measuring device to ensure accurate dosing.
Storing and Disposing of Your Medication
Store your medication 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 it. Discard any unused portion of the liquid suspension after 30 days. Keep all medications in a safe and secure location, out of the reach of children and pets.
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 a missed dose.
To get the most benefit from your medication, 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 trouble 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. When measuring your liquid dose, use the measuring device that comes with your medication. If one is not provided, ask your pharmacist for a suitable measuring device to ensure accurate dosing.
Storing and Disposing of Your Medication
Store your medication 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 it. Discard any unused portion of the liquid suspension after 30 days. Keep all medications in a safe and secure location, out of the reach of children and pets.
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 a missed dose.
Lifestyle & Tips
- Take medication exactly as prescribed, do not skip doses or double up.
- Avoid sudden changes in position (e.g., standing up quickly) to prevent dizziness.
- Stay hydrated to help manage dry mouth.
- Report any new or worsening symptoms to your doctor immediately.
- Avoid alcohol and grapefruit juice as they may interact with this medication.
Available Forms & Alternatives
Available Strengths:
Dosing & Administration
Adult Dosing
Standard Dose:
100 mg every 6 hours (immediate release) or 300 mg every 12 hours (extended release)
Dose Range:
400 - 800 mg
Condition-Specific Dosing:
initialLoadingDose:
300 mg (immediate release) followed by 100 mg every 6 hours, or 200 mg every 6 hours for patients with cardiomyopathy or cardiac decompensation.
maintenanceDose:
400-800 mg/day in divided doses.
Pediatric Dosing
Neonatal:
Not established
Infant:
Not established
Child:
Not established (use generally not recommended due to proarrhythmic risk and anticholinergic effects)
Adolescent:
Not established
Dose Adjustments
Renal Impairment:
Mild:
CrCl 40-90 mL/min: 100 mg every 8 hours or 150 mg every 12 hours.
Moderate:
CrCl 15-40 mL/min: 100 mg every 10 hours or 100 mg every 12 hours.
Severe:
CrCl <15 mL/min: 100 mg every 20 hours or 100 mg every 24 hours.
Dialysis:
Administer 100 mg every 24 hours; supplemental dose of 100 mg after each dialysis session.
Hepatic Impairment:
Mild:
Reduce dose by 25-50% or extend dosing interval.
Moderate:
Reduce dose by 25-50% or extend dosing interval.
Severe:
Reduce dose by 25-50% or extend dosing interval.
Pharmacology
Mechanism of Action
Disopyramide is a Class IA antiarrhythmic agent that blocks fast inward sodium channels (NaV1.5) in myocardial cells, leading to a decrease in the rate of depolarization, an increase in the action potential duration, and an increase in the effective refractory period. It also possesses significant anticholinergic properties.
Pharmacokinetics
Absorption:
Bioavailability:
80-90%
Tmax:
0.5-3 hours (immediate release)
FoodEffect:
Food can delay absorption but does not significantly affect the extent of absorption.
Distribution:
Vd:
1.5-2.5 L/kg
ProteinBinding:
50-90% (concentration-dependent)
CnssPenetration:
Limited
Elimination:
HalfLife:
4-10 hours (average 6-8 hours)
Clearance:
Not available
ExcretionRoute:
Renal (50-70%), Fecal (10-20%)
Unchanged:
50-70%
Pharmacodynamics
OnsetOfAction:
30 minutes - 2 hours
PeakEffect:
1-3 hours
DurationOfAction:
6-8 hours
Safety & Warnings
BLACK BOX WARNING
Increased mortality in patients with non-life-threatening arrhythmias. Disopyramide has a negative inotropic effect and may cause or worsen congestive heart failure. It should be used with extreme caution in patients with pre-existing heart failure or a history of heart failure.
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, contact your doctor immediately.
Heart failure has been reported with this medication, including worsening heart failure in people with pre-existing heart disease. If you have 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. Many people may not experience any side effects or may only have mild symptoms. If you experience any of the following side effects, or if they bother you or persist, contact your doctor or seek medical attention:
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, contact 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, contact your doctor immediately.
Heart failure has been reported with this medication, including worsening heart failure in people with pre-existing heart disease. If you have 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. Many people may not experience any side effects or may only have mild symptoms. If you experience any of the following side effects, or if they bother you or persist, contact your doctor or seek medical attention:
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, contact 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 irregular heartbeats (palpitations, fluttering)
- Severe dizziness, lightheadedness, or fainting spells
- Shortness of breath, swelling in your ankles or feet, or sudden weight gain (signs of heart failure)
- Severe dry mouth, blurred vision, difficulty urinating, or severe constipation (anticholinergic effects)
- Chest pain
- Unusual bleeding or bruising
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. Describe the allergic reaction you experienced, including the 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. 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. Describe the allergic reaction you experienced, including the 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. 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. Before consuming alcohol, discuss the potential risks with your doctor. If you are 65 years or older, use this medication with caution, as you may be more susceptible to side effects. Additionally, if you are pregnant, planning to become pregnant, or breastfeeding, consult your doctor to discuss the potential benefits and risks to both you and your baby.
Overdose Information
Overdose Symptoms:
- Severe hypotension (low blood pressure)
- Widening of the QRS complex on ECG
- Prolonged QT interval
- AV block, asystole (cardiac arrest)
- Severe anticholinergic effects (e.g., delirium, urinary retention, paralytic ileus, severe dry mouth, dilated pupils)
- Respiratory depression
- Coma
What to Do:
Call 911 or your local emergency number immediately. For poison control, call 1-800-222-1222. Treatment may include gastric lavage, activated charcoal, vasopressors for hypotension, atropine for bradycardia, and correction of electrolyte imbalances. Cardiac pacing may be required. Hemodialysis may be effective in removing disopyramide.
Drug Interactions
Contraindicated Interactions
- Other QT-prolonging drugs (e.g., quinidine, procainamide, amiodarone, sotalol, macrolide antibiotics, fluoroquinolones, tricyclic antidepressants)
- Strong CYP3A4 inhibitors (e.g., ketoconazole, ritonavir, clarithromycin)
Major Interactions
- Beta-blockers (additive negative inotropic effects)
- Calcium channel blockers (additive negative inotropic and chronotropic effects)
- Digoxin (may increase digoxin levels, additive bradycardia)
- Anticholinergic drugs (additive anticholinergic effects)
- Drugs causing hypokalemia or hypomagnesemia (e.g., diuretics, laxatives) - increase risk of Torsades de Pointes
Moderate Interactions
- CYP3A4 inducers (e.g., phenytoin, rifampin, carbamazepine, phenobarbital) - may decrease disopyramide levels
- Warfarin (potential for increased INR, though not consistently reported)
Minor Interactions
- Not many specific minor interactions; general caution with drugs affecting cardiac function.
Monitoring
Baseline Monitoring
Electrocardiogram (ECG)
Rationale: To assess baseline PR, QRS, and QTc intervals and identify pre-existing conduction abnormalities or prolonged QT interval.
Timing: Prior to initiation of therapy
Serum Electrolytes (Potassium, Magnesium)
Rationale: Electrolyte imbalances (hypokalemia, hypomagnesemia) can increase the risk of proarrhythmia.
Timing: Prior to initiation of therapy
Renal Function (BUN, Serum Creatinine)
Rationale: Disopyramide is primarily renally eliminated; dose adjustments are necessary in renal impairment.
Timing: Prior to initiation of therapy
Hepatic Function (LFTs)
Rationale: Disopyramide is metabolized in the liver; dose adjustments may be necessary in hepatic impairment.
Timing: Prior to initiation of therapy
Blood Pressure and Heart Rate
Rationale: To establish baseline cardiovascular status.
Timing: Prior to initiation of therapy
Symptoms of Heart Failure
Rationale: Disopyramide has negative inotropic effects and can worsen heart failure.
Timing: Prior to initiation of therapy
Routine Monitoring
Electrocardiogram (ECG) - PR, QRS, QTc intervals
Frequency: Weekly initially, then monthly or as clinically indicated; more frequently with dose changes or new symptoms.
Target: QRS widening >25% of baseline or QTc prolongation >500 ms (or >25% of baseline) may require dose reduction or discontinuation.
Action Threshold: Significant QRS widening, QTc prolongation, or new arrhythmias.
Serum Electrolytes (Potassium, Magnesium)
Frequency: Periodically, especially if diuretics are co-administered or if symptoms of arrhythmia worsen.
Target: Maintain within normal limits (e.g., K+ >4.0 mEq/L, Mg++ >2.0 mEq/L).
Action Threshold: Abnormal levels; correct before or during therapy.
Renal and Hepatic Function
Frequency: Periodically (e.g., every 3-6 months) or as clinically indicated.
Target: Within normal limits or stable for patient.
Action Threshold: Significant decline in function; adjust dose accordingly.
Disopyramide Serum Levels
Frequency: If clinical response is inadequate, toxicity is suspected, or in patients with renal/hepatic impairment.
Target: Therapeutic range: 2-5 mcg/mL (total disopyramide).
Action Threshold: Levels outside therapeutic range; adjust dose.
Blood Pressure and Heart Rate
Frequency: Regularly.
Target: Within patient's normal range.
Action Threshold: Significant hypotension or bradycardia.
Symptom Monitoring
- Worsening or new arrhythmias (palpitations, dizziness, fainting)
- Signs of heart failure (shortness of breath, swelling of ankles/feet, weight gain)
- Anticholinergic effects (dry mouth, blurred vision, urinary retention, constipation)
- Dizziness, lightheadedness, syncope
- Chest pain
Special Patient Groups
Pregnancy
Disopyramide is classified as Pregnancy Category C. It should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. It crosses the placenta.
Trimester-Specific Risks:
First Trimester:
Potential for fetal harm, but human data are limited. Use only if clearly needed.
Second Trimester:
Potential for fetal harm, but human data are limited. Use only if clearly needed.
Third Trimester:
Potential for fetal harm, including uterine contractions (due to anticholinergic effects) and neonatal effects. Use with caution.
Lactation
Disopyramide is excreted into breast milk. The American Academy of Pediatrics considers it compatible with breastfeeding, but caution is advised. Monitor the infant for anticholinergic effects (e.g., dry mouth, constipation, urinary retention) or signs of arrhythmia.
Infant Risk:
Low to moderate risk. Monitor for anticholinergic effects, feeding difficulties, or cardiac effects.
Pediatric Use
Safety and efficacy have not been established in pediatric patients. Use is generally not recommended due to the risk of proarrhythmia and significant anticholinergic effects.
Geriatric Use
Elderly patients may be more susceptible to the anticholinergic effects (e.g., urinary retention, constipation, confusion) and negative inotropic effects of disopyramide. Renal function often declines with age, necessitating dose adjustments. Start with lower doses and titrate carefully.
Clinical Information
Clinical Pearls
- Disopyramide has potent anticholinergic effects, which can be problematic, especially in elderly patients or those with prostatic hypertrophy or glaucoma.
- It has a significant negative inotropic effect and should be used with extreme caution, or avoided, in patients with heart failure or impaired left ventricular function.
- Close monitoring of ECG (QRS duration, QTc interval) and serum electrolytes (potassium, magnesium) is crucial due to the risk of proarrhythmia, including Torsades de Pointes.
- Dose adjustments are essential in patients with renal or hepatic impairment.
- Therapeutic drug monitoring (TDM) of disopyramide levels can be useful, especially in patients with renal/hepatic dysfunction, drug interactions, or suspected toxicity/non-response.
Alternative Therapies
- Other Class IA antiarrhythmics (e.g., Quinidine, Procainamide - though less commonly used)
- Class IC antiarrhythmics (e.g., Flecainide, Propafenone - for structurally normal hearts)
- Class III antiarrhythmics (e.g., Amiodarone, Sotalol, Dofetilide)
- Beta-blockers (e.g., Metoprolol, Propranolol)
- Calcium channel blockers (e.g., Diltiazem, Verapamil - for rate control)
- Catheter ablation procedures
Cost & Coverage
Average Cost:
Varies widely, typically $30-$200+ per 30 capsules (100mg)
Generic Available:
Yes
Insurance Coverage:
Tier 1 or 2 for generic, Tier 3 or higher for brand
General Drug Facts
If your symptoms or health issues persist or worsen, it is essential to contact your doctor promptly. 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 it is a good idea to consult with your pharmacist. If you have any questions or concerns about this medication, do not hesitate to discuss them with your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek emergency medical attention. When seeking help, be prepared to provide detailed information about the overdose, including the medication taken, the amount, and the time it occurred.