Rythmol 225mg Tablets

Propafenone is a Class Ic antiarrhythmic agent. It exerts its effects by blocking fast voltage-gated sodium channels in myocardial cells, leading to a reduction in the maximum rate of depolarization (Vmax) of the action potential. This results in a marked decrease in impulse conduction velocity in the atria, AV node, and ventricles. It also has weak beta-blocking and calcium channel blocking properties, but its primary antiarrhythmic effect is due to sodium channel blockade.

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 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 immediately 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 counts, 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 help 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.

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 contraindicated.

Please note that this is not an exhaustive list of all potential interactions or health problems that may affect the safety of this medication. Therefore, 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.

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 before starting treatment. Additionally, if you have myasthenia gravis, discuss your condition with your doctor, as this medication may worsen 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 treatment. An electrocardiogram (ECG) will be required before initiating this medication and periodically during treatment. Discuss the schedule and any concerns with your doctor.

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.

This medication may decrease sperm count, 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, inform your doctor. It is essential to discuss the benefits and risks of this medication to both you and your baby to make an informed decision about treatment.

• Ritonavir
• Saquinavir
• Lopinavir/Ritonavir
• Other strong CYP2D6 inhibitors (in poor metabolizers or if significant accumulation occurs)
• Quinidine (in extensive metabolizers, converts them to poor metabolizer phenotype)

• 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)
• Other antiarrhythmics (e.g., amiodarone, disopyramide, flecainide, quinidine - increased proarrhythmic risk, increased levels)
• Strong CYP2D6 inhibitors (e.g., fluoxetine, paroxetine, sertraline - significantly increases propafenone levels)
• Strong CYP3A4 inhibitors (e.g., ketoconazole, clarithromycin - increases propafenone levels)

• Cimetidine (increases propafenone levels)
• Rifampin (decreases propafenone levels)
• Grapefruit juice (may increase propafenone levels)
• Phenobarbital, Phenytoin (may decrease propafenone levels)
• Theophylline (increases theophylline levels)

• Not specifically categorized as minor for clinically significant interactions, but general caution with drugs affecting cardiac conduction.

• Palpitations (new or worsening)
• Dizziness
• Lightheadedness
• Syncope (fainting)
• Chest pain
• Shortness of breath
• Fatigue
• Nausea
• Unusual taste (metallic taste)

Propafenone is 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 American Academy of Pediatrics classifies it as a drug for which the effect on nursing infants is unknown but may be of concern. Lactation Risk Category L3 (Moderate Risk). Weigh the benefits of breastfeeding against the potential risks to the infant.

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.

Elderly patients may be more sensitive to the effects of propafenone, particularly regarding conduction disturbances and CNS effects. Start with lower doses and titrate slowly. Monitor renal and hepatic function closely.

• Propafenone has a black box warning due to increased mortality in patients with structural heart disease (e.g., post-MI, heart failure). Always rule out structural heart disease before initiation.
• It exhibits dose-dependent and genetically polymorphic metabolism (CYP2D6). Poor metabolizers will have significantly higher drug levels and longer half-lives, requiring lower doses.
• Monitor ECG closely for QRS widening (>25% increase from baseline or >0.18 seconds) as this indicates excessive sodium channel blockade and requires dose reduction or discontinuation.
• Metallic taste is a common and often bothersome side effect.
• Correct hypokalemia and hypomagnesemia before and during therapy to minimize proarrhythmic risk.
• Propafenone has weak beta-blocking activity, which can contribute to bradycardia or bronchospasm in susceptible individuals.
• Significant drug interactions exist, especially with CYP2D6 inhibitors (e.g., quinidine, fluoxetine, paroxetine) and drugs that prolong the QT interval or affect cardiac conduction.

• Flecainide (another Class Ic antiarrhythmic)
• Amiodarone (Class III antiarrhythmic)
• Sotalol (Class III and beta-blocker)
• Dofetilide (Class III antiarrhythmic)
• Catheter ablation (non-pharmacological)
• Electrical cardioversion (non-pharmacological)

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. If you have any questions or concerns about this medication, don't hesitate to discuss them with 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 reporting the incident, be prepared to provide details about the medication taken, the amount, and the time it occurred.