Propafenone 150mg 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 (Sodium Channel Blocker)
Pregnancy Category
C
FDA Approved
Oct 1989
DEA Schedule
Not Controlled
Overview
What is this medicine?
Propafenone is a medication used to treat certain types of irregular heartbeats (arrhythmias). It works by affecting the electrical signals in your heart to help it beat more regularly. It's often used for conditions like atrial fibrillation or other fast heart rhythms.
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
Store your medication at room temperature, away from light and moisture. Keep it in a dry place, avoiding storage in a bathroom. Make sure to keep the lid tightly closed.
Missing a Dose
If you miss a dose, skip it and take your next dose at the usual time. 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
Store your medication at room temperature, away from light and moisture. Keep it in a dry place, avoiding storage in a bathroom. Make sure to keep the lid tightly closed.
Missing a Dose
If you miss a dose, skip it and take your next dose at the usual time. 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 stop abruptly without consulting your doctor.
- Avoid grapefruit and grapefruit juice, as they can increase drug levels.
- Report any new or worsening heart symptoms (e.g., palpitations, dizziness, fainting, shortness of breath, chest pain) immediately.
- Maintain regular follow-up appointments and blood tests as advised by your doctor.
- Inform all healthcare providers that you are taking propafenone, especially before any surgery or dental procedures.
- Avoid excessive alcohol consumption.
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 if needed. Max: 300 mg every 8 hours.
Dose Range:
150 - 300 mg
Condition-Specific Dosing:
Paroxysmal Supraventricular Tachycardia (PSVT):
Initial 150 mg every 8 hours, may increase to 225 mg every 8 hours, then 300 mg every 8 hours.
Paroxysmal Atrial Fibrillation/Flutter (PAF):
Initial 150 mg every 8 hours, may increase to 225 mg every 8 hours, then 300 mg every 8 hours.
Life-threatening Ventricular Arrhythmias:
Initial 150 mg every 8 hours, may increase to 225 mg every 8 hours, then 300 mg every 8 hours.
Pediatric Dosing
Neonatal:
Not established
Infant:
Not established
Child:
Not established (Use generally not recommended due to proarrhythmic risk and lack of data)
Adolescent:
Not established (Use generally not recommended due to proarrhythmic risk and lack of data)
Dose Adjustments
Renal Impairment:
Mild:
No specific adjustment, monitor closely.
Moderate:
No specific adjustment, monitor closely.
Severe:
Use with caution, consider dose reduction and extended dosing intervals. Monitor ECG and drug levels if possible.
Dialysis:
Not significantly removed by hemodialysis. Use with caution, monitor closely.
Hepatic Impairment:
Mild:
Reduce dose by 20-30%, monitor closely.
Moderate:
Reduce dose by 50% or more, monitor closely. Consider extended dosing intervals.
Severe:
Contraindicated due to extensive hepatic metabolism and risk of accumulation.
Pharmacology
Mechanism of Action
Propafenone is a Class Ic antiarrhythmic agent. It exerts its antiarrhythmic effect by blocking the fast inward sodium current (INa) in myocardial cells, leading to a dose-dependent reduction in the rate of rise of the action potential (Vmax) and a prolongation of the effective refractory period in the atria, AV node, and ventricles. It also has weak beta-blocking and calcium channel blocking activity.
Pharmacokinetics
Absorption:
Bioavailability:
10-50% (highly variable due to extensive first-pass metabolism)
Tmax:
2-3 hours
FoodEffect:
Food increases bioavailability and peak plasma concentrations.
Distribution:
Vd:
250 L (extensive tissue distribution)
ProteinBinding:
Approximately 95% (primarily to alpha1-acid glycoprotein and albumin)
CnssPenetration:
Limited
Elimination:
HalfLife:
Biphasic: 2-10 hours (extensive metabolizers); 10-32 hours (poor metabolizers)
Clearance:
Highly variable due to genetic polymorphism (CYP2D6)
ExcretionRoute:
Renal (38%) and Fecal (53%)
Unchanged:
Approximately 1% (renal)
Pharmacodynamics
OnsetOfAction:
Within 1 hour (oral)
PeakEffect:
2-3 hours
DurationOfAction:
8-12 hours
Safety & Warnings
BLACK BOX WARNING
Propafenone is contraindicated in patients with structural heart disease (e.g., myocardial infarction, heart failure, or left ventricular dysfunction) due to increased mortality observed in the Cardiac Arrhythmia Suppression Trial (CAST) with other Class Ic antiarrhythmic drugs. Propafenone should be reserved for patients with life-threatening ventricular arrhythmias or for patients with supraventricular arrhythmias who do not have structural heart disease and for whom other treatments are ineffective or not tolerated.
Side Effects
Serious Side Effects: Seek Medical Attention Immediately
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor or seek medical help right away:
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 reported with this medication, and it can worsen existing heart failure. 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
Low white blood cell counts have been reported, increasing the risk of infection. If you have a history of low white blood cell count, inform your doctor. Seek medical attention immediately 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 or any other unusual symptoms, contact your doctor or seek medical help:
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, 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 notice any of the following symptoms, contact your doctor or seek medical help right away:
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 reported with this medication, and it can worsen existing heart failure. 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
Low white blood cell counts have been reported, increasing the risk of infection. If you have a history of low white blood cell count, inform your doctor. Seek medical attention immediately 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 or any other unusual symptoms, contact your doctor or seek medical help:
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, 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, skipped beats)
- Severe dizziness or lightheadedness, fainting
- Shortness of breath, swelling in ankles/feet, unusual weight gain (signs of heart failure)
- Chest pain
- Blurred vision or other vision changes
- Unusual bleeding or bruising
- Yellowing of skin or eyes (jaundice), dark urine, persistent nausea/vomiting (signs of liver problems)
- Severe metallic taste or taste disturbance
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 medications (prescription or over-the-counter), 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. There are many medications that interact with this drug, so it is crucial to consult with your doctor or pharmacist to determine if any of your current medications are incompatible with this medication.
Please note that this is not an exhaustive list of all potential interactions or health problems that may affect the use of this medication. To ensure your safety, it is vital to:
Inform your doctor and pharmacist about all your medications (prescription or over-the-counter), natural products, and vitamins
Discuss all your health problems with your doctor and pharmacist
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 medications (prescription or over-the-counter), 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. There are many medications that interact with this drug, so it is crucial to consult with your doctor or pharmacist to determine if any of your current medications are incompatible with this medication.
Please note that this is not an exhaustive list of all potential interactions or health problems that may affect the use of this medication. To ensure your safety, it is vital to:
Inform your doctor and pharmacist about all your medications (prescription or over-the-counter), natural products, and vitamins
Discuss all your health problems with your doctor and pharmacist
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 lab personnel that you are taking this drug. If you have previously had an abnormal result on an Antinuclear Antibody Test (ANA test), 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 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 the details with your doctor.
To avoid potential interactions, refrain from consuming grapefruit and 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.
Men taking this medication should be aware that it may lower sperm counts, potentially affecting fertility. If you have concerns about fathering a child, discuss this 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 lab personnel that you are taking this drug. If you have previously had an abnormal result on an Antinuclear Antibody Test (ANA test), 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 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 the details with your doctor.
To avoid potential interactions, refrain from consuming grapefruit and 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.
Men taking this medication should be aware that it may lower sperm counts, potentially affecting fertility. If you have concerns about fathering a child, discuss this 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, heart block)
- Ventricular tachycardia/fibrillation
- Asystole
- Convulsions
- Respiratory depression
What to Do:
Seek immediate medical attention or call 911. For poison control, call 1-800-222-1222. Treatment is supportive and may include IV fluids, vasopressors, atropine, temporary pacing, and in severe cases, extracorporeal membrane oxygenation (ECMO) or lipid emulsion therapy.
Drug Interactions
Contraindicated Interactions
- Ritonavir (strong CYP3A4 inhibitor)
- Quinidine (strong CYP2D6 inhibitor in poor metabolizers)
Major Interactions
- Amiodarone (increased propafenone levels, increased risk of proarrhythmia)
- Beta-blockers (e.g., metoprolol, propranolol - increased beta-blocker levels, additive bradycardia/hypotension)
- Calcium channel blockers (e.g., verapamil, diltiazem - additive negative inotropic/chronotropic effects)
- Digoxin (increased digoxin levels, monitor digoxin levels)
- Warfarin (increased INR, monitor INR closely)
- Local anesthetics (e.g., lidocaine - additive CNS effects, increased risk of seizures)
- CYP2D6 inhibitors (e.g., fluoxetine, paroxetine, sertraline - significantly increase propafenone levels)
- CYP3A4 inhibitors (e.g., ketoconazole, clarithromycin, grapefruit juice - increase propafenone levels)
Moderate Interactions
- Cimetidine (increased propafenone levels)
- Rifampin (decreased propafenone levels)
- Phenobarbital, Phenytoin (decreased propafenone levels)
- Theophylline (increased theophylline levels)
- Oral hypoglycemics (potential for altered glucose control)
Minor Interactions
- Not available
Monitoring
Baseline Monitoring
Electrocardiogram (ECG)
Rationale: To assess baseline PR, QRS, and QT intervals, and identify pre-existing conduction abnormalities or structural heart disease.
Timing: Prior to initiation of therapy
Electrolytes (Potassium, Magnesium)
Rationale: Electrolyte imbalances can exacerbate proarrhythmic effects. Hypokalemia and hypomagnesemia should be corrected prior to and during therapy.
Timing: Prior to initiation of therapy
Renal function (BUN, Creatinine)
Rationale: To assess kidney function, as propafenone and its metabolites are partially renally excreted.
Timing: Prior to initiation of therapy
Hepatic function (ALT, AST, Bilirubin)
Rationale: To assess liver function, as propafenone is extensively metabolized by the liver.
Timing: Prior to initiation of therapy
Blood Pressure and Heart Rate
Rationale: To establish baseline cardiovascular status.
Timing: Prior to initiation of therapy
Routine Monitoring
Electrocardiogram (ECG)
Frequency: Regularly, especially during dose titration and with any change in clinical status. At least monthly for the first 3 months, then every 3-6 months.
Target: QRS duration increase <25% from baseline; PR and QT intervals within normal limits or acceptable clinical range.
Action Threshold: QRS duration increase >25% from baseline, new or worsening heart block, significant QT prolongation, or new arrhythmias. Consider dose reduction or discontinuation.
Electrolytes (Potassium, Magnesium)
Frequency: Periodically, especially if diuretics or other electrolyte-altering drugs are used, or if symptoms of imbalance occur.
Target: Potassium: 3.5-5.0 mEq/L; Magnesium: 1.7-2.2 mg/dL
Action Threshold: Values outside normal range; correct imbalances promptly.
Blood Pressure and Heart Rate
Frequency: Regularly, especially during dose titration.
Target: Within patient's normal range, without symptomatic hypotension or bradycardia.
Action Threshold: Symptomatic hypotension, significant bradycardia (<50 bpm), or signs of heart failure.
Hepatic function (ALT, AST)
Frequency: Periodically, especially in patients with pre-existing hepatic impairment or signs of liver dysfunction.
Target: Within normal limits.
Action Threshold: Significant elevation of liver enzymes (e.g., >3x ULN).
Symptom Monitoring
- New or worsening arrhythmias (palpitations, dizziness, syncope)
- Signs of heart failure (shortness of breath, edema, weight gain)
- Dizziness, lightheadedness, blurred vision
- Nausea, vomiting, constipation
- Unusual taste sensation (metallic taste)
- Chest pain, shortness of breath
- Signs of liver dysfunction (jaundice, dark urine, persistent nausea/vomiting)
Special Patient Groups
Pregnancy
Propafenone is classified as Pregnancy Category C. It should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Animal studies have shown adverse effects on the fetus at high doses.
Trimester-Specific Risks:
First Trimester:
Potential for teratogenicity, though human data are limited and conflicting. Use only if clearly needed.
Second Trimester:
Potential for fetal bradycardia or other arrhythmias. Monitor fetal heart rate and growth.
Third Trimester:
Potential for fetal bradycardia or other arrhythmias, and effects on neonatal heart function. Monitor neonate for cardiac effects.
Lactation
Propafenone is excreted into breast milk. The amount is small, but potential for adverse effects on the infant exists. The American Academy of Pediatrics considers it a drug for which the effect on nursing infants is unknown but may be of concern. Use with caution, or consider an alternative.
Infant Risk:
L3 (Moderate concern) - Potential for bradycardia, arrhythmias, or other cardiac effects in the infant. Monitor infant for signs of adverse effects.
Pediatric Use
Safety and effectiveness in pediatric patients have not been established. Use is generally not recommended due to the risk of proarrhythmia and lack of sufficient data. If used in life-threatening situations, extreme caution and close monitoring are required.
Geriatric Use
Use with caution in elderly patients, as they may be more susceptible to adverse effects, particularly proarrhythmia and central nervous system effects. Start with lower doses and titrate slowly. Monitor renal and hepatic function closely.
Clinical Information
Clinical Pearls
- Propafenone has a significant first-pass effect and exhibits dose-dependent pharmacokinetics, meaning small dose increases can lead to disproportionately large increases in plasma concentrations.
- Genetic polymorphism of CYP2D6 significantly impacts propafenone metabolism; poor metabolizers will have higher and more prolonged drug levels.
- The most critical monitoring parameter is the QRS duration on ECG. A QRS widening of >25% from baseline indicates excessive sodium channel blockade and warrants dose reduction or discontinuation due to increased proarrhythmic risk.
- Always rule out structural heart disease before initiating propafenone due to the Black Box Warning.
- Propafenone can cause a metallic taste, which can be bothersome for some patients.
- It has weak beta-blocking activity, which can contribute to bradycardia or exacerbate heart failure in susceptible patients.
Alternative Therapies
- Flecainide (another Class Ic antiarrhythmic)
- Amiodarone (Class III antiarrhythmic)
- Dofetilide (Class III antiarrhythmic)
- Sotalol (Class III antiarrhythmic with beta-blocking activity)
- Beta-blockers (e.g., metoprolol, atenolol)
- Calcium channel blockers (e.g., diltiazem, verapamil)
- Catheter ablation (non-pharmacological)
Cost & Coverage
Average Cost:
Varies widely ($30-$150) per 30 tablets
Generic Available:
Yes
Insurance Coverage:
Tier 1 or 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 emergency medical attention. When seeking help, be prepared to provide details about the medication taken, the amount, and the time it happened.