Propafenone SR 325mg Capsules

Propafenone is a Class IC antiarrhythmic agent. It exerts its effects by blocking the fast inward sodium current (INa) in myocardial cells, leading to a concentration-dependent reduction in the maximum rate of depolarization (Vmax) of the action potential. This results in a decrease in impulse conduction velocity in the atria, AV node, and ventricles. It also possesses weak beta-blocking activity and calcium channel blocking activity, but its primary antiarrhythmic effect is due to sodium channel blockade.

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 notice any of the following symptoms, contact your doctor or seek immediate medical attention:

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 immediate medical attention 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 with similar medications, increasing the risk of infection. If you have a history of low white blood cell counts, inform your doctor. Seek medical attention 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 are bothered by any of the following side effects or if they persist, contact your doctor:

Dizziness, tiredness, or weakness
Upset stomach or vomiting
Constipation
Changes in taste
Headache
Anxiety
* Symptoms 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.

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:
+ 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 any medications to treat abnormal heart rhythms
If you are taking any prescription or over-the-counter (OTC) medications, natural products, or vitamins that may interact with this medication. Certain medications, such as those used to treat HIV, infections, or depression, should not be taken with this drug. Your doctor or pharmacist can advise you on potential interactions.

Please note that this is not an exhaustive list of all possible interactions or health problems that may affect the safety of this medication. To ensure your safety, it is crucial to:

Inform your doctor and pharmacist about all your medications (prescription and OTC), natural products, vitamins, and health problems
Verify that it is safe to take this medication with all your other medications and health conditions
* Avoid starting, stopping, or changing the dose of any medication without consulting your doctor first.

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 result on an Antinuclear Antibody Test (ANA test), consult with your doctor to discuss any potential implications.

If you have myasthenia gravis, a condition that causes muscle weakness, it is vital to discuss your treatment with your doctor, as this medication may worsen symptoms. If you experience any worsening of symptoms, contact your doctor immediately.

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 treatment to monitor your heart's activity.

To avoid potential interactions, do not consume grapefruit or grapefruit juice while taking this medication.

Notify your doctor if you experience any signs of dehydration, such as excessive sweating, vomiting, diarrhea, decreased appetite, or unusual thirst, as these may affect your treatment.

This medication may decrease sperm count, 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 discuss the benefits and risks of this medication with your doctor to ensure the best possible outcome for you and your baby.

• Ritonavir (due to significant increase in propafenone levels)
• Quinidine (in poor metabolizers, due to inhibition of CYP2D6)
• Severe hepatic impairment

• Other Class I antiarrhythmics (e.g., flecainide, disopyramide) - increased proarrhythmic risk
• Beta-blockers (e.g., metoprolol, propranolol) - increased levels of both drugs, additive bradycardia/hypotension
• Digoxin - increased digoxin levels
• Warfarin - increased INR/bleeding risk
• CYP2D6 inhibitors (e.g., fluoxetine, paroxetine, sertraline, amiodarone) - significantly increased propafenone levels
• CYP3A4 inhibitors (e.g., ketoconazole, erythromycin, grapefruit juice) - increased propafenone levels
• Local anesthetics (e.g., lidocaine) - additive CNS effects

• Cimetidine - increased propafenone levels
• Rifampin - decreased propafenone levels
• Phenobarbital - decreased propafenone levels
• Theophylline - increased theophylline levels
• Cyclosporine - increased cyclosporine levels

• Not available

• New or worsening arrhythmias (palpitations, dizziness, syncope)
• Shortness of breath, chest pain, swelling (signs of heart failure)
• Dizziness, lightheadedness, blurred vision (CNS effects)
• Nausea, vomiting, constipation (GI effects)
• Unusual bleeding or bruising (if on warfarin)
• Signs of liver dysfunction (yellowing of skin/eyes, dark urine, persistent nausea/vomiting)

Use only if the potential benefit justifies the potential risk to the fetus. Animal studies show adverse effects, but human data are limited. Propafenone crosses the placenta.

Propafenone is excreted into breast milk. The amount is small, but potential for adverse effects on the infant exists. Use with caution; monitor infant for bradycardia or other signs of toxicity. Consider alternative if possible.

Safety and effectiveness have not been established in pediatric patients. Use is generally not recommended.

Use with caution in elderly patients, as they may be more susceptible to adverse effects due to decreased renal and hepatic function. Start with lower doses and titrate slowly. Monitor ECG and drug levels closely.

• Propafenone is a 'pill-in-the-pocket' option for some patients with infrequent, symptomatic AF, but this should only be initiated under direct medical supervision and after careful patient selection (e.g., no structural heart disease, normal QT interval).
• Genetic polymorphism of CYP2D6 significantly impacts propafenone metabolism. Poor metabolizers will have significantly higher and more prolonged plasma concentrations, requiring lower doses.
• Always rule out structural heart disease before initiating propafenone due to the black box warning regarding increased mortality.
• Monitor ECG for QRS widening and PR prolongation; these are indicators of excessive sodium channel blockade and potential proarrhythmia.
• Correct hypokalemia and hypomagnesemia prior to and during propafenone therapy to minimize proarrhythmic risk.

• Flecainide (another Class IC antiarrhythmic)
• Amiodarone (Class III antiarrhythmic)
• Dofetilide (Class III antiarrhythmic)
• Sotalol (Class III antiarrhythmic with beta-blocking properties)
• Catheter ablation (non-pharmacological)

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.