Propafenone 300mg Tablets
WARNING: This drug is only to be used to treat certain types of abnormal heartbeats. Other abnormal heartbeats have happened with this drug. This 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.
Drug Class
Antiarrhythmic
Pharmacologic Class
Class Ic Antiarrhythmic
Pregnancy Category
Category C
FDA Approved
Dec 1989
DEA Schedule
Not Controlled
Overview
What is this medicine?
Propafenone is a medication used to help your heart beat regularly if you have certain types of irregular heart rhythms (arrhythmias), such as atrial fibrillation or supraventricular tachycardia. It works by affecting the electrical signals in your heart to help restore a normal rhythm.
How to Use This Medicine
Taking Your Medication
To use this medication correctly, follow your doctor's instructions and read all the information provided. Take your medication as directed, with or without food. It's essential to continue taking this medication as prescribed by your doctor or healthcare provider, even if you're feeling well.
Storing and Disposing of Your Medication
To maintain the quality and effectiveness of your medication, store it at room temperature, protected from light, and in a dry place. Avoid storing it in a bathroom. Keep the lid tightly closed when not in use.
Missing a Dose
If you miss a dose, skip it 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 use this medication correctly, follow your doctor's instructions and read all the information provided. Take your medication as directed, with or without food. It's essential to continue taking this medication as prescribed by your doctor or healthcare provider, even if you're feeling well.
Storing and Disposing of Your Medication
To maintain the quality and effectiveness of your medication, store it at room temperature, protected from light, and in a dry place. Avoid storing it in a bathroom. Keep the lid tightly closed when not in use.
Missing a Dose
If you miss a dose, skip it 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, usually with food to reduce stomach upset.
- Do not crush, chew, or break extended-release tablets.
- Avoid grapefruit juice as it can increase the amount of propafenone in your body.
- Limit or avoid alcohol, as it can worsen heart rhythm problems.
- Report any new or worsening symptoms of irregular heartbeat, dizziness, shortness of breath, or swelling to your doctor immediately.
- Do not stop taking this medication suddenly without consulting your doctor.
Available Forms & Alternatives
Dosing & Administration
Adult Dosing
Standard Dose:
Initial 150 mg every 8 hours; may increase to 225 mg every 8 hours after 3-4 days, then to 300 mg every 8 hours if needed and tolerated. Max 900 mg/day.
Dose Range:
150 - 300 mg
Condition-Specific Dosing:
paroxysmalSupraventricularTachycardia:
Initial 150 mg every 8 hours, titrate as needed.
paroxysmalAtrialFibrillationFlutter:
Initial 150 mg every 8 hours, titrate as needed.
Pediatric Dosing
Neonatal:
Not established
Infant:
Not established
Child:
Not established (limited data, generally not recommended)
Adolescent:
Not established (limited data, generally not recommended)
Dose Adjustments
Renal Impairment:
Mild:
No specific adjustment usually needed, monitor for adverse effects.
Moderate:
No specific adjustment usually needed, monitor for adverse effects.
Severe:
Use with caution; monitor for increased drug levels and adverse effects due to potential accumulation of metabolites.
Dialysis:
Not significantly dialyzable. Use with caution, monitor closely.
Hepatic Impairment:
Mild:
Reduce dose by 20-30% or administer less frequently.
Moderate:
Significant dose reduction (e.g., 50%) or contraindication depending on severity. Monitor closely.
Severe:
Contraindicated or use with extreme caution and significant dose reduction (e.g., 70-80% reduction) due to extensive hepatic metabolism.
Pharmacology
Mechanism of Action
Propafenone is a Class Ic antiarrhythmic agent. It acts by blocking the fast inward sodium current (INa) in myocardial cells, leading to a marked decrease in the maximum rate of depolarization (Vmax) of the action potential. This effect is most pronounced in Purkinje fibers and ventricular muscle, slowing conduction velocity in the atria, AV node, and ventricles. It also has weak beta-blocking and calcium channel blocking activity.
Pharmacokinetics
Absorption:
Bioavailability:
5-50% (highly variable due to extensive first-pass metabolism, especially in extensive metabolizers)
Tmax:
2-3 hours (immediate release)
FoodEffect:
Food may increase bioavailability slightly and reduce Cmax variability.
Distribution:
Vd:
1.9-3.0 L/kg
ProteinBinding:
Approximately 95% (primarily to alpha1-acid glycoprotein and albumin)
CnssPenetration:
Yes (can cause CNS side effects)
Elimination:
HalfLife:
2-10 hours (extensive metabolizers); 10-32 hours (poor metabolizers)
Clearance:
Highly variable, dependent on CYP2D6 phenotype.
ExcretionRoute:
Renal (approx. 38%), Fecal (approx. 53%)
Unchanged:
Less than 1% (renal)
Pharmacodynamics
OnsetOfAction:
Within 1 hour (oral)
PeakEffect:
2-3 hours
DurationOfAction:
8-12 hours (variable based on metabolizer status)
Safety & Warnings
BLACK BOX WARNING
Propafenone is contraindicated in patients with structural heart disease (e.g., myocardial infarction, heart failure) due to an increased risk of proarrhythmia (new or worsened arrhythmias). The CAST (Cardiac Arrhythmia Suppression Trial) study showed an increased mortality in patients with asymptomatic or mildly symptomatic ventricular arrhythmias after myocardial infarction treated with Class Ic antiarrhythmics (flecainide or encainide). While propafenone was not studied in CAST, it has similar electrophysiologic effects and should be avoided in this population.
Side Effects
Urgent Side Effects: Seek Medical Help Right Away
While rare, some people may experience severe and potentially life-threatening side effects when taking this medication. If you notice 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
Chest pain or pressure
Fast or slow heartbeat
Severe dizziness or fainting
New or worsening abnormal heartbeat
Blurred vision
Important Warnings
Heart failure has been associated with this medication, and it can worsen existing heart disease. If you have a history of heart disease, inform your doctor. Seek medical attention right away if you experience:
+ Shortness of breath
+ Sudden weight gain
+ Irregular heartbeat
+ New or worsening swelling in the arms or legs
Low white blood cell counts have been reported with this medication, increasing the risk of infection. If you have a history of low white blood cell count, inform your doctor. Seek medical attention right away if you experience signs of infection, such as:
+ Fever
+ Chills
+ Sore throat
Other Possible Side Effects
Most people do not experience significant side effects, but some may occur. If you experience any of the following side effects, contact your doctor or seek medical attention if they bother you or do not go away:
Dizziness, tiredness, or weakness
Upset stomach or vomiting
Constipation
Change in taste
Headache
Anxiety
* Signs of a common cold
Reporting Side Effects
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.
While rare, some people may experience severe and potentially life-threatening side effects when taking this medication. If you notice 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
Chest pain or pressure
Fast or slow heartbeat
Severe dizziness or fainting
New or worsening abnormal heartbeat
Blurred vision
Important Warnings
Heart failure has been associated with this medication, and it can worsen existing heart disease. If you have a history of heart disease, inform your doctor. Seek medical attention right away if you experience:
+ Shortness of breath
+ Sudden weight gain
+ Irregular heartbeat
+ New or worsening swelling in the arms or legs
Low white blood cell counts have been reported with this medication, increasing the risk of infection. If you have a history of low white blood cell count, inform your doctor. Seek medical attention right away if you experience signs of infection, such as:
+ Fever
+ Chills
+ Sore throat
Other Possible Side Effects
Most people do not experience significant side effects, but some may occur. If you experience any of the following side effects, contact your doctor or seek medical attention if they bother you or do not go away:
Dizziness, tiredness, or weakness
Upset stomach or vomiting
Constipation
Change in taste
Headache
Anxiety
* Signs of a common cold
Reporting Side Effects
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 palpitations or irregular heartbeats
- Severe dizziness or lightheadedness
- Fainting (syncope)
- Shortness of breath or difficulty breathing
- Swelling in your ankles, feet, or legs
- Chest pain
- Unusual fatigue or weakness
- Yellowing of skin or eyes (jaundice)
- 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. Be sure to describe the allergic reaction and its symptoms.
Certain health conditions, such as:
+ Breathing or lung problems
+ Brugada syndrome
+ Electrolyte imbalances in your blood
+ Low blood pressure
+ Recent heart attack
+ Sick sinus syndrome or heart block without a functioning pacemaker
+ Shock caused by heart problems
+ Slow heartbeat
+ Heart failure
If you have been taking medications to treat abnormal heart rhythms
If you are taking any prescription or over-the-counter medications, natural products, or vitamins that should not be taken with this medication. This includes certain medications used to treat HIV, infections, depression, and other conditions. Your doctor or pharmacist can advise you on potential interactions.
Please note that this is not an exhaustive list of all medications or health conditions that may interact with this drug. To ensure your safety, it is crucial to:
Inform your doctor and pharmacist about all your medications (prescription and over-the-counter), natural products, and vitamins
Discuss your health problems with your doctor
Verify that it is safe to take this medication with all your other medications and health conditions
Never start, stop, or change the dose of any medication without consulting 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. Be sure to describe the allergic reaction and its symptoms.
Certain health conditions, such as:
+ Breathing or lung problems
+ Brugada syndrome
+ Electrolyte imbalances in your blood
+ Low blood pressure
+ Recent heart attack
+ Sick sinus syndrome or heart block without a functioning pacemaker
+ Shock caused by heart problems
+ Slow heartbeat
+ Heart failure
If you have been taking medications to treat abnormal heart rhythms
If you are taking any prescription or over-the-counter medications, natural products, or vitamins that should not be taken with this medication. This includes certain medications used to treat HIV, infections, depression, and other conditions. Your doctor or pharmacist can advise you on potential interactions.
Please note that this is not an exhaustive list of all medications or health conditions that may interact with this drug. To ensure your safety, it is crucial to:
Inform your doctor and pharmacist about all your medications (prescription and over-the-counter), natural products, and vitamins
Discuss your health problems with your doctor
Verify that it is safe to take this medication with all your other medications and health conditions
Never start, stop, or change the dose of any medication without consulting your doctor.
Precautions & Cautions
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication. Regular blood tests will be necessary, as directed by your doctor, to monitor your condition. Be sure to discuss any concerns or questions you have with your doctor.
This medication may interfere with certain laboratory tests, so it is crucial to notify all your healthcare providers and laboratory personnel that you are taking this drug. If you have previously had an abnormal Antinuclear Antibody Test (ANA test) result, consult with your doctor to discuss any potential implications.
If you have myasthenia gravis, it is vital to discuss your condition with your doctor, as this medication may worsen your symptoms. Monitor your condition closely and contact your doctor if your symptoms deteriorate.
If you have a defibrillator or pacemaker, consult with your doctor before starting this medication. An electrocardiogram (ECG) will be required before initiating treatment and at regular intervals during therapy. Discuss any concerns or questions you have with your doctor.
To avoid potential interactions, do not consume grapefruit or grapefruit juice while taking this medication. If you experience excessive fluid loss, unusual sweating, vomiting, diarrhea, decreased appetite, or unusual thirst, notify your doctor promptly.
This medication may decrease sperm counts, which could affect fertility. If you have questions or concerns about this potential side effect, discuss them with your doctor.
If you are pregnant, planning to become pregnant, or breastfeeding, it is essential to consult with your doctor to weigh the benefits and risks of this medication to both you and your baby.
This medication may interfere with certain laboratory tests, so it is crucial to notify all your healthcare providers and laboratory personnel that you are taking this drug. If you have previously had an abnormal Antinuclear Antibody Test (ANA test) result, consult with your doctor to discuss any potential implications.
If you have myasthenia gravis, it is vital to discuss your condition with your doctor, as this medication may worsen your symptoms. Monitor your condition closely and contact your doctor if your symptoms deteriorate.
If you have a defibrillator or pacemaker, consult with your doctor before starting this medication. An electrocardiogram (ECG) will be required before initiating treatment and at regular intervals during therapy. Discuss any concerns or questions you have with your doctor.
To avoid potential interactions, do not consume grapefruit or grapefruit juice while taking this medication. If you experience excessive fluid loss, unusual sweating, vomiting, diarrhea, decreased appetite, or unusual thirst, notify your doctor promptly.
This medication may decrease sperm counts, which could affect fertility. If you have questions or concerns about this potential side effect, discuss them with your doctor.
If you are pregnant, planning to become pregnant, or breastfeeding, it is essential to consult with your doctor to weigh the benefits and risks of this medication to both you and your baby.
Overdose Information
Overdose Symptoms:
- Severe hypotension (low blood pressure)
- Bradycardia (slow heart rate)
- Intraventricular conduction disturbances (e.g., QRS widening)
- Ventricular tachycardia or fibrillation
- Asystole
- Convulsions
- Somnolence
- Coma
What to Do:
Seek immediate medical attention or call Poison Control (1-800-222-1222). Treatment is supportive, including IV fluids, vasopressors for hypotension, atropine for bradycardia, and potentially sodium bicarbonate for QRS widening. External pacing or defibrillation may be necessary. Hemodialysis is not effective.
Drug Interactions
Contraindicated Interactions
- Ritonavir (significant increase in propafenone levels)
- Quinidine (in poor metabolizers, can significantly increase propafenone levels)
- Patients with structural heart disease (e.g., post-myocardial infarction, heart failure) due to increased risk of proarrhythmia.
Major Interactions
- Digoxin (propafenone increases digoxin levels, monitor digoxin levels)
- Warfarin (propafenone may potentiate anticoagulant effect, monitor INR)
- Beta-blockers (e.g., metoprolol, propranolol - increased levels of both drugs, additive bradycardia/hypotension)
- Other antiarrhythmics (e.g., amiodarone, disopyramide, flecainide, quinidine - increased risk of proarrhythmia, QT prolongation)
- Local anesthetics (e.g., lidocaine - additive CNS and cardiac effects)
- CYP2D6 inhibitors (e.g., fluoxetine, paroxetine, cimetidine - significant increase in propafenone levels, dose reduction needed)
- CYP3A4 inhibitors (e.g., ketoconazole, erythromycin - increased propafenone levels)
Moderate Interactions
- CYP1A2 inhibitors (e.g., ciprofloxacin - moderate increase in propafenone levels)
- Grapefruit juice (inhibits CYP3A4, potential for increased propafenone levels)
- Rifampin (CYP inducers, may decrease propafenone levels)
Minor Interactions
- Not available
Monitoring
Baseline Monitoring
Electrocardiogram (ECG)
Rationale: To assess baseline PR, QRS, and QT intervals and identify pre-existing conduction abnormalities.
Timing: Prior to initiation of therapy.
Serum Electrolytes (Potassium, Magnesium)
Rationale: Electrolyte imbalances can predispose to arrhythmias and alter propafenone's effects.
Timing: Prior to initiation of therapy and corrected if abnormal.
Renal Function (BUN, Creatinine)
Rationale: To assess kidney function, especially in severe impairment where metabolite accumulation may occur.
Timing: Prior to initiation of therapy.
Hepatic Function (ALT, AST, Bilirubin)
Rationale: Propafenone is extensively metabolized by the liver; hepatic impairment requires dose adjustment.
Timing: Prior to initiation of therapy.
Routine Monitoring
Electrocardiogram (ECG)
Frequency: Regularly during dose titration and periodically during maintenance (e.g., every 3-6 months or as clinically indicated).
Target: QRS duration should not increase by more than 25% from baseline; PR and QT intervals should be monitored for significant prolongation.
Action Threshold: If QRS widens by >25% or new conduction abnormalities occur, consider dose reduction or discontinuation. Significant QT prolongation (e.g., QTc >500 ms) warrants immediate evaluation.
Heart Rate and Blood Pressure
Frequency: Regularly, especially during initiation and dose changes.
Target: Maintain within normal limits; avoid significant bradycardia or hypotension.
Action Threshold: Significant bradycardia (<50 bpm) or hypotension warrants evaluation.
Serum Electrolytes (Potassium, Magnesium)
Frequency: Periodically, especially if on diuretics or with GI losses.
Target: Maintain within normal limits (K 3.5-5.0 mEq/L, Mg 1.7-2.2 mg/dL).
Action Threshold: Correct any imbalances promptly.
Symptoms of Arrhythmia or Heart Failure
Frequency: Ongoing patient assessment.
Target: Absence of symptoms.
Action Threshold: New or worsening palpitations, dizziness, syncope, shortness of breath, edema, or chest pain require immediate medical attention.
Symptom Monitoring
- Palpitations
- Dizziness
- Lightheadedness
- Syncope (fainting)
- Shortness of breath
- Chest pain
- Fatigue
- Edema (swelling of ankles/feet)
- Nausea
- Unusual taste (metallic taste)
Special Patient Groups
Pregnancy
Use during pregnancy only if the potential benefit justifies the potential risk to the fetus. Animal studies show adverse effects at high doses, but human data are limited.
Trimester-Specific Risks:
First Trimester:
Potential for teratogenicity, though human data are inconclusive.
Second Trimester:
Risk of fetal bradycardia or other cardiac effects.
Third Trimester:
Risk of fetal bradycardia or other cardiac effects, potential for neonatal effects if used close to delivery.
Lactation
Propafenone is excreted into breast milk. While the amount is small, monitor breastfed infants for signs of adverse effects (e.g., bradycardia, feeding difficulties). Use with caution, or consider an alternative if possible.
Infant Risk:
Low to moderate risk (L3).
Pediatric Use
Safety and efficacy have not been established in pediatric patients. Use is generally not recommended due to limited data and potential for serious adverse effects.
Geriatric Use
Elderly patients may be more sensitive to the effects of propafenone due to age-related decreases in hepatic and renal function, and potential for polypharmacy. Initiate at lower doses and titrate slowly, monitoring closely for adverse effects and drug interactions.
Clinical Information
Clinical Pearls
- Propafenone is contraindicated in patients with structural heart disease due to increased proarrhythmic risk. Always assess for underlying heart disease before initiation.
- Genetic polymorphism of CYP2D6 significantly impacts propafenone metabolism. Poor metabolizers will have higher and more prolonged drug levels, requiring lower doses.
- Monitor ECG (PR, QRS, QT intervals) closely during initiation and dose titration. A QRS widening of >25% from baseline suggests excessive sodium channel blockade and warrants dose reduction.
- Electrolyte imbalances (especially hypokalemia and hypomagnesemia) must be corrected before and during propafenone therapy to minimize proarrhythmic risk.
- Patients may experience a metallic taste, which is a common but usually benign side effect.
- Propafenone has weak beta-blocking activity, which can contribute to bradycardia or bronchospasm in susceptible individuals.
Alternative Therapies
- Flecainide (another Class Ic antiarrhythmic)
- Amiodarone (Class III antiarrhythmic)
- Dofetilide (Class III antiarrhythmic)
- Sotalol (Class III antiarrhythmic with beta-blocking properties)
- Dronedarone (Class III antiarrhythmic)
- Beta-blockers (e.g., metoprolol, atenolol)
- Calcium channel blockers (e.g., diltiazem, verapamil)
- Catheter ablation (non-pharmacologic)
Cost & Coverage
Average Cost:
$30 - $150 per 30 tablets (300mg)
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 this 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 overdose, including the medication taken, the amount, and the time it occurred.