Rythmol 150mg Tablets

Propafenone is a Class Ic antiarrhythmic agent. It acts primarily by blocking the fast inward sodium current (INa) in myocardial cells, leading to a dose-dependent reduction in the maximum rate of depolarization (Vmax) of the action potential. This effect slows conduction in the atria, AV node, and ventricles. It also possesses weak beta-adrenergic blocking activity and a mild calcium channel blocking effect.

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 passing out
Abnormal heartbeat that is new or worse
Blurred eyesight

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 help right away if you experience:

Shortness of breath
Sudden weight gain
Abnormal heartbeat
New or worsening swelling in the arms or legs

Additionally, this medication can cause low white blood cell counts, which may increase the risk of infection. If you have a history of low white blood cell counts, inform your doctor. Seek medical help 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:

Feeling dizzy, tired, or weak
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.

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 your 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 first consulting your doctor.

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

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, refrain from consuming grapefruit and grapefruit juice while taking this medication. Additionally, if you experience excessive fluid loss, unusual sweating, vomiting, diarrhea, decreased appetite, or excessive thirst, notify your doctor, as these symptoms may indicate a need to adjust your treatment.

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 discuss the benefits and risks of this medication with your doctor to ensure the best possible outcome for you and your baby.

• Ritonavir (significant increase in propafenone levels)
• Quinidine (significant increase in propafenone levels, especially in extensive metabolizers)
• Amiodarone (increased risk of proarrhythmia and toxicity)

• Digoxin (increases digoxin levels, monitor digoxin levels)
• Warfarin (potentiates anticoagulant effect, monitor INR)
• Beta-blockers (e.g., metoprolol, propranolol - increased levels of beta-blockers, additive bradycardia/hypotension)
• Local anesthetics (e.g., lidocaine - additive CNS and cardiac effects)
• Other antiarrhythmics (e.g., flecainide, disopyramide - increased risk of proarrhythmia)
• CYP2D6 inhibitors (e.g., fluoxetine, paroxetine, sertraline - increase propafenone levels)
• CYP3A4 inhibitors (e.g., ketoconazole, clarithromycin, grapefruit juice - increase propafenone levels)
• CYP1A2 inhibitors (e.g., cimetidine, fluvoxamine - increase propafenone levels)

• Rifampin (induces CYP enzymes, decreases propafenone levels)
• Phenobarbital, Phenytoin (induce CYP enzymes, decrease propafenone levels)
• Theophylline (propafenone may increase theophylline levels)
• Cyclosporine (propafenone may increase cyclosporine levels)

• Not available

• New or worsening arrhythmias (palpitations, dizziness, syncope)
• Chest pain
• Shortness of breath
• Signs of heart failure (edema, weight gain)
• Dizziness, lightheadedness
• Blurred vision or other visual disturbances
• Nausea, vomiting, constipation
• Unusual bleeding or bruising (if on warfarin)
• Signs of liver dysfunction (jaundice, dark urine, persistent fatigue)

Propafenone is classified as Pregnancy Category C. Animal studies have shown adverse effects on the fetus, but there are no adequate and well-controlled studies in pregnant women. Use only if the potential benefit justifies the potential risk to the fetus.

Propafenone is excreted into breast milk. The amount is small, but the potential for serious adverse reactions in the nursing infant exists. A decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother. Lactation risk is L3 (moderately safe).

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

Use with caution in elderly patients, as they may be more susceptible to the adverse effects of propafenone, particularly central nervous system effects and conduction disturbances. Start with lower doses and titrate slowly, monitoring closely for adverse effects and therapeutic response. Consider age-related decline in renal and hepatic function.

• Propafenone is a Class Ic antiarrhythmic with a significant Black Box Warning against use in patients with structural heart disease due to increased mortality risk.
• Genetic polymorphism of CYP2D6 significantly impacts propafenone metabolism and half-life. Poor metabolizers will have higher and more prolonged plasma levels, requiring lower doses.
• Always correct electrolyte imbalances (especially hypokalemia and hypomagnesemia) before and during propafenone therapy to minimize proarrhythmic risk.
• Monitor ECG (PR, QRS, QT intervals) closely, especially during initiation and dose titration. A QRS widening of >25% from baseline may indicate toxicity and warrant dose reduction.
• Propafenone has weak beta-blocking activity, which can contribute to bradycardia and bronchospasm in susceptible individuals.
• Food increases propafenone bioavailability; consistent administration with food is recommended to maintain stable drug levels.
• Be aware of numerous drug interactions, particularly with other antiarrhythmics, CYP inhibitors/inducers, digoxin, and warfarin.

• Flecainide (another Class Ic antiarrhythmic, similar contraindications)
• Amiodarone (Class III antiarrhythmic, broad spectrum, different side effect profile)
• Sotalol (Class III and beta-blocker)
• Dofetilide (Class III antiarrhythmic)
• Dronedarone (Class III antiarrhythmic, less effective than amiodarone, specific contraindications)
• Beta-blockers (e.g., metoprolol, atenolol - for rate control or certain arrhythmias)
• Calcium channel blockers (e.g., diltiazem, verapamil - for rate control)
• Catheter ablation (non-pharmacological intervention for arrhythmias)

If your symptoms or health issues persist or worsen, it is 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 it's a good idea 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 emergency medical attention. When seeking help, be prepared to provide details about the medication, including the amount taken and the time it happened, to facilitate prompt and effective treatment.