Rythmol SR (Oral)

Propafenone is used to prevent irregular heartbeats, like atrial fibrillation (AF), from coming back in patients who do not have structural heart disease.

Propafenone is part of a group of medicines called antiarrhythmics. It works directly on the heart tissue and slows down the nerve impulses in the heart. This helps keep the heart rhythm normal.

There is a chance that propafenone may cause new heart rhythm problems or make existing ones worse when it is used. Since it has been shown to cause severe problems in some patients, propafenone is only used to treat serious heart rhythm issues. Talk to your doctor about this possible effect.

This medicine is available only with your doctor's prescription.

It is important for your doctor to check your progress during regular visits to ensure the medicine is working properly. This will help make adjustments to your dosage if needed.

This medicine can cause changes in your heart rhythm, including conditions known as PR, QRS, or QT prolongation. It may lead to fainting or serious side effects in some patients. Contact your doctor immediately if your symptoms do not improve or worsen.

Check with your doctor right away if you experience any of the following: chest pain, shortness of breath, swelling in your hands, ankles, or feet, or weight gain. These may be signs of heart failure.

This medicine can temporarily reduce the number of white blood cells in your blood, which increases the risk of infections. If possible, avoid contact with people who are sick. Contact your doctor immediately if you think you might have an infection, or if you develop a fever or chills, cough or hoarseness, lower back or side pain, or painful or difficult urination.

Make sure any doctor or dentist who treats you knows that you are taking this medicine. This medicine may affect the results of certain medical tests.

Propafenone may cause some people to feel dizzy or lightheaded. Be aware of how you respond to this medicine before driving, operating machines, or doing anything else that could be dangerous if you feel dizzy.

If you have been using this medicine regularly for several weeks, do not stop suddenly. Talk to your doctor about the best way to gradually reduce your dosage before stopping completely.

This medicine may lower the amount of sperm produced in men. Discuss any concerns about this with your doctor.

Grapefruits and grapefruit juice can increase the effects of propafenone by raising the level of this medicine in your body. You should not eat grapefruit or drink grapefruit juice while taking this medicine.

Inform your doctor if you are smoking tobacco.

Do not take any other medicines unless you have discussed them with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

In deciding to use a medication, the chances of taking the medication must be weighed against the good it will do. This is a decision you and your clinician will make. For this medicine, the following should be considered:

Allergies

Inform your doctor if you have ever had any unusual or allergic reaction to this medication or any other medications. As well inform your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.

Pediatric

Appropriate studies have not been performed on the relationship of age to the effects of propafenone in the pediatric population. Safety and efficacy have not been established.

Geriatric

Appropriate studies performed to date have not demonstrated geriatric-specific issues that would limit the usefulness of propafenone in the elderly.

Breast Feeding

There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks prior to using this medication while breastfeeding.

Interactions with Drugs

Although certain medicines should not be used together at all, in other cases two different drugs may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are using this medicine, it is especially important that your healthcare professional know if you are using any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medications is not recommended. Your doctor may decide not to treat you with this medicine or change some of the other medications you take.

• Bepridil
• Cisapride
• Dronedarone
• Fluconazole
• Ketoconazole
• Levoketoconazole
• Levomethadyl
• Mesoridazine
• Nelfinavir
• Nirmatrelvir
• Pimozide
• Piperaquine
• Posaconazole
• Ritonavir
• Saquinavir
• Sparfloxacin
• Terfenadine
• Thioridazine
• Tipranavir
• Vernakalant
• Ziprasidone

Using this drug with any of the following medicines is normally not advised, but may be required in some cases. If both drugs are prescribed together, your physician may change the dose or how frequently you use one or both of the drugs.

• Abiraterone Acetate
• Acecainide
• Adagrasib
• Ajmaline
• Alfuzosin
• Amiodarone
• Amisulpride
• Amitriptyline
• Amoxapine
• Anagrelide
• Apomorphine
• Aprindine
• Aripiprazole
• Aripiprazole Lauroxil
• Arsenic Trioxide
• Artemether
• Asenapine
• Astemizole
• Atazanavir
• Azimilide
• Azithromycin
• Boceprevir
• Bretylium
• Buprenorphine
• Bupropion
• Buserelin
• Ceritinib
• Chloral Hydrate
• Chloroquine
• Chlorpromazine
• Ciprofloxacin
• Citalopram
• Clarithromycin
• Clofazimine
• Clomipramine
• Clothiapine
• Clozapine
• Cobicistat
• Crizotinib
• Dabrafenib
• Darunavir
• Dasabuvir
• Dasatinib
• Degarelix
• Delamanid
• Delavirdine
• Desipramine
• Deslorelin
• Desvenlafaxine
• Deutetrabenazine
• Dexmedetomidine
• Dibenzepin
• Digoxin
• Disopyramide
• Dofetilide
• Dolasetron
• Domperidone
• Donepezil
• Droperidol
• Duloxetine
• Efavirenz
• Encorafenib
• Enflurane
• Entrectinib
• Erythromycin
• Escitalopram
• Etrasimod
• Etravirine
• Fedratinib
• Fexinidazole
• Fingolimod
• Flecainide
• Fluoxetine
• Formoterol
• Foscarnet
• Fostemsavir
• Gatifloxacin
• Gemifloxacin
• Gepirone
• Glasdegib
• Gonadorelin
• Goserelin
• Granisetron
• Halofantrine
• Haloperidol
• Halothane
• Histrelin
• Hydroquinidine
• Hydroxychloroquine
• Hydroxyzine
• Ibutilide
• Iloperidone
• Imipramine
• Inotuzumab Ozogamicin
• Isoflurane
• Isradipine
• Ivabradine
• Ivosidenib
• Lacosamide
• Lapatinib
• Lefamulin
• Lenvatinib
• Leuprolide
• Levofloxacin
• Lidocaine
• Lidoflazine
• Lofexidine
• Lopinavir
• Lorcainide
• Lumefantrine
• Macimorelin
• Mefloquine
• Methadone
• Metronidazole
• Mifepristone
• Mirabegron
• Mirtazapine
• Mobocertinib
• Moxifloxacin
• Nafarelin
• Nilotinib
• Norfloxacin
• Nortriptyline
• Octreotide
• Olanzapine
• Ombitasvir
• Ondansetron
• Osilodrostat
• Osimertinib
• Oxaliplatin
• Ozanimod
• Pacritinib
• Paliperidone
• Panobinostat
• Paritaprevir
• Paroxetine
• Pasireotide
• Pazopanib
• Pentamidine
• Phenobarbital
• Pimavanserin
• Pirmenol
• Pitolisant
• Ponesimod
• Prajmaline
• Prilocaine
• Primidone
• Probucol
• Procainamide
• Prochlorperazine
• Promethazine
• Protriptyline
• Quetiapine
• Quinidine
• Quinine
• Quizartinib
• Ranolazine
• Relugolix
• Ribociclib
• Risperidone
• Selpercatinib
• Sematilide
• Sertindole
• Sertraline
• Sevoflurane
• Simeprevir
• Siponimod
• Sodium Phosphate
• Sodium Phosphate, Dibasic
• Sodium Phosphate, Monobasic
• Solifenacin
• Sorafenib
• Sotalol
• Spiramycin
• Sulfamethoxazole
• Sulpiride
• Sultopride
• Sunitinib
• Tacrolimus
• Tedisamil
• Telaprevir
• Telithromycin
• Tetrabenazine
• Tizanidine
• Toremifene
• Trazodone
• Triclabendazole
• Trifluoperazine
• Trimethoprim
• Trimipramine
• Triptorelin
• Vandetanib
• Vardenafil
• Vemurafenib
• Venlafaxine
• Vilanterol
• Vinflunine
• Voclosporin
• Voriconazole
• Zolmitriptan
• Zotepine
• Zuclopenthixol

Using this drug with any of the following drugs may cause an increased chance of certain adverse effects, but using both drugs may be the best therapy for you. If both medications are prescribed together, your doctor may change the dose or how frequently you use one or both of the medications.

• Cyclosporine
• Metoprolol
• Rifampin
• Rifapentine
• Theophylline
• Tolterodine
• Warfarin

Interactions with Food/Tobacco/Alcohol

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medications may also cause interactions to occur. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medication with any of the following is usually not recommended, but may be unavoidable in some cases. If used together, your doctor may change the dose or how frequently you use this medicine, or give you special instructions about the use of food, alcohol, or tobacco.

• Grapefruit Juice
• Tobacco

Other Medical Issues

The presence of other medical issues may affect the use of this medicine. Make sure you inform your physician if you have any other medical problems, especially:

• Asthma or
• Bronchitis or
• Emphysema—Propafenone can increase trouble in breathing.

• AV block (type of abnormal heart rhythm), with no pacemaker or
• Bradycardia (slow heartbeat) or
• Breathing problems or lung disease (eg, bronchospasm, severe obstructive pulmonary disease) or
• Brugada syndrome (a genetic heart rhythm disorder) or
• Cardiogenic shock (shock caused by heart attack) or
• Heart failure or
• Hypotension (low blood pressure) or
• Mineral imbalance or
• Sick sinus node syndrome (type of abnormal heart rhythm), with no pacemaker—Should not be used in patients with these conditions.

• Blood or bone marrow issues (eg, agranulocytosis, granulocytopenia) or
• Coronary artery disease or
• Heart rhythm issues (eg, QT prolongation) or
• Myasthenia gravis (serious muscle weakness) or
• Torsade de pointes or
• Ventricular fibrillation or tachycardia—Use with caution. May make these conditions worse.

• Kidney disease or
• Liver disease—Use with caution. The effects may be increased since of slower removal of the drug from the body.

• If you have a permanent pacemaker—Use with caution. Propafenone may interfere with the pacemaker and require more careful follow-up by the doctor.

Along with its needed effects, Rythmol SR (Oral) may cause some unwanted effects. Not all of these side effects may occur, but if they do, they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

Less common

• Chest pain
• fast, irregular, or slow heartbeat
• lightheadedness, dizziness, or fainting
• shortness of breath
• swelling of the feet or lower legs
• weight gain

Rare

• Chills
• fever
• joint pain
• trembling or shaking
• weakness

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to Rythmol SR (Oral). Your health care professional may also be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome, or if you have any questions about them:

More common

• Change in taste or bitter or metallic taste

Less common

• Blurred vision
• constipation
• diarrhea
• dryness of the mouth
• headache
• nausea or vomiting
• skin rash
• unusual tiredness or weakness

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

In the U.S.

• Rythmol
• Rythmol SR

Available Dosage Forms:

• Capsule, Extended Release
• Tablet

Therapeutic Class: Antiarrhythmic, Group IC

Chemical Class: Propafenone

Take this medicine exactly as directed by your doctor. Do not take more or less of this medicine, and do not take it more often than your doctor ordered.

This medicine comes with a patient information leaflet. Read and follow the instructions carefully. Ask your doctor if you have any questions.

For patients taking the extended-release capsules:

• Swallow the capsules whole. Do not crush, break, or chew them.
• This medicine may be taken with or without food.

This medicine works best when there is a constant amount in the blood. To help keep the amount constant, do not miss any doses. Also, it is best to take each dose at evenly spaced times day and night. For example, if you are to take 3 doses a day, doses should be spaced about 8 hours apart. If you need help in planning the best times to take your medicine, check with your doctor.

Your doctor may want you to carry a medical identification card or bracelet stating that you are using this medicine.

Dosing

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

• The number of extended-release capsules or tablets that you take depends on the strength of the medicine.
• For atrial fibrillation (AF): For oral dosage form (extended-release capsules): Adults—At first, 225 milligrams (mg) every 12 hours. Your doctor may adjust your dose as needed. However, the dose is usually not more than 425 mg every 12 hours. Children—Use and dose must be determined by your doctor. For oral dosage form (tablets): Adults—150 milligrams (mg) every 8 hours. Your doctor may increase your dose if needed. Children—Use and dose must be determined by your doctor.

Missed Dose

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Storage

Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Ask your healthcare professional how you should dispose of any medicine you do not use.