Rythmol 300mg Tablets

Propafenone is a Class Ic antiarrhythmic agent. It exerts its primary electrophysiologic effect by blocking the fast inward sodium current (INa) in myocardial cells, leading to a marked reduction in the maximum rate of depolarization (Vmax) of the action potential. This results in a dose-dependent decrease in the excitability of myocardial cells, slowing conduction velocity in the atria, AV node, and ventricles. It also has weak beta-adrenergic blocking activity and calcium channel blocking activity, though these are less significant to its antiarrhythmic 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 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
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 reported with this medication, and it can worsen existing heart disease. If you have a history of heart disease, inform your doctor. Seek medical attention immediately if you experience:
+ Shortness of breath
+ Sudden weight gain
+ Abnormal heartbeat
+ Swelling in the arms or legs that is new or worsening
Low white blood cell counts have been reported, which can increase 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, 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, 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 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. This includes certain medications used to treat HIV, infections, depression, and other conditions. There are many medications that should not be taken 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 between this medication and other drugs or health conditions. To ensure your safety, it is vital to:

Inform your doctor and pharmacist about all your medications (prescription and OTC), natural products, vitamins, and health conditions
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 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.

As this medication may interfere with certain laboratory tests, 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), 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 immediately if your symptoms deteriorate.

Additionally, 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. Your doctor will discuss the details with you.

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 excessive 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.

It is also essential to inform your doctor if you are pregnant, planning to become pregnant, or are breast-feeding. Your doctor will help you weigh the benefits and risks of taking this medication during this time, considering both your health and the health of your baby.

• Ritonavir
• Saquinavir
• Lopinavir/Ritonavir
• Other Class Ic antiarrhythmics (e.g., flecainide) in combination
• Patients with structural heart disease (e.g., myocardial infarction, heart failure) due to increased mortality risk

• Digoxin (increases digoxin levels)
• Warfarin (potentiates anticoagulant effect)
• Beta-blockers (e.g., metoprolol, propranolol - increased levels of both drugs)
• Calcium channel blockers (e.g., verapamil, diltiazem - increased levels of both drugs, additive negative inotropic/chronotropic effects)
• Local anesthetics (e.g., lidocaine - increased CNS toxicity)
• CYP2D6 inhibitors (e.g., fluoxetine, paroxetine, quinidine - significantly increase propafenone levels)
• CYP3A4 inhibitors (e.g., ketoconazole, erythromycin - increase propafenone levels)
• Amiodarone (increased propafenone levels, increased risk of proarrhythmia)
• Cimetidine (increases propafenone levels)

• Rifampin (decreases propafenone levels)
• Phenobarbital (decreases propafenone levels)
• Grapefruit juice (may increase propafenone levels)
• Theophylline (propafenone may increase theophylline levels)
• Cyclosporine (propafenone may increase cyclosporine levels)

• Not specifically categorized, but caution with any drug affecting cardiac conduction or metabolism.

• New or worsening palpitations
• Dizziness
• Lightheadedness
• Syncope (fainting)
• Chest pain
• Shortness of breath
• Swelling of ankles/feet (signs of heart failure)
• Blurred vision
• Nausea
• Unusual taste (metallic taste)

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

Propafenone is excreted into breast milk. The American Academy of Pediatrics considers it a drug for which the effect on the nursing infant is unknown but may be of concern. Use with caution; monitor infant for adverse effects (e.g., bradycardia, feeding difficulties). Consider alternative agents or temporary discontinuation of breastfeeding.

Safety and effectiveness have not been established in pediatric patients. Use is generally not recommended for routine antiarrhythmic therapy in children due to limited data and potential for serious adverse effects. If used, it is typically off-label and under specialist supervision.

Elderly patients may be more sensitive to the effects of propafenone due to age-related decreases in renal and hepatic function, and potential for polypharmacy. Initiate therapy at lower doses and titrate slowly with careful monitoring of ECG and clinical response. Increased risk of adverse effects.

• Propafenone has a Black Box Warning regarding increased mortality in patients with structural heart disease (e.g., post-MI, heart failure). It should be avoided in these patients.
• Propafenone metabolism is highly dependent on CYP2D6 activity. Patients who are poor metabolizers of CYP2D6 will have significantly higher and more prolonged plasma concentrations of propafenone, requiring lower doses and careful monitoring.
• ECG monitoring is crucial during initiation and dose titration to assess for QRS widening (should not exceed 25% of baseline or 0.18 seconds), PR prolongation, and QT prolongation, which indicate excessive sodium channel blockade.
• Propafenone has weak beta-blocking activity, which can contribute to bradycardia or bronchospasm in susceptible individuals.
• Metallic taste is a common and often bothersome side effect.
• Correct hypokalemia and hypomagnesemia prior to and during propafenone therapy, as electrolyte imbalances can increase the risk of proarrhythmia.

• Other Class Ic antiarrhythmics (e.g., flecainide - with similar contraindications)
• Class III antiarrhythmics (e.g., amiodarone, sotalol, dofetilide, dronedarone)
• Class II antiarrhythmics (beta-blockers, e.g., metoprolol, atenolol)
• Class IV antiarrhythmics (calcium channel blockers, e.g., diltiazem, verapamil)
• Catheter ablation (for certain arrhythmias like atrial fibrillation or supraventricular tachycardia)

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 medical attention. When seeking help, be prepared to provide details about the medication taken, the amount, and the time it occurred.