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Does Rythmol (propafenone) cause side effects?
Rythmol is effective in
- atrial tachycardia,
- AV nodal tachycardia, and
- bypass tract tachycardias.
Rythmol is also effective in suppressing the recurrence of atrial fibrillation and supra-ventricular tachycardia once normal sinus rhythm has been restored. Rythmol is at least as effective as any other type I agent in converting atrial fibrillation to normal sinus rhythm.
Common side effects of Rythmol include
- blurred vision,
- loss of appetite,
- unusual taste,
- reduced cardiac conduction,
- nausea, and
Serious side effects of Rythmol include
- chest pain,
- heart palpitations,
- increased rate of cardiac arrest,
- abnormal heart beats,
- aggravation of myasthenia gravis,
- increased rate of death,
- congestive heart failure, and
- serious life-threatening irregular heart rhythms (ventricular arrhythmias or pro-arrhythmia) or heart block.
Rythmol increases the levels of
Rifampin increases the metabolism of Rythmol, decreasing blood levels of Rythmol. Orlistat may reduce the absorption of Rythmol.
Stopping orlistat in patients stabilized on Rythmol may result in Rythmol toxicity because more Rythmol will be absorbed after discontinuation of orlistat.
Rythmol may alter pacing and sensing thresholds of pacemakers and defibrillators.
These devices should be re-programmed and closely monitored. Safety and efficacy of Rythmol in pregnant women have not been established. Rythmol is excreted in breast milk. Mothers should decide whether to stop breastfeeding or discontinue Rythmol.
What are the important side effects of Rythmol (propafenone)?
Common side effects of propafenone are:
- Blurred vision
- Unusual taste
- Reduced cardiac conduction
- Nausea and vomiting
Serious side effects of propafenone include:
- Chest pain
- Heart palpitations
- Increased rate of cardiac arrest
- Abnormal heart beats
- Aggravation of myasthenia gravis
- Increased rate of death
- Congestive heart failure
Because of its beta blocking activity, propafenone must be used with caution in patients with
- weak heart muscle (congestive heart failure),
- slow heart rate,
- any form of heart electrical conduction block,
- low blood pressure, or
The most serious side effect of propafenone is the causing of serious life-threatening irregular heart rhythms (ventricular arrhythmias or pro-arrhythmia) or heart block. It is for this reason that propafenone is started and doses increased while patients are hospitalized in a monitored setting.
Rythmol (propafenone) side effects list for healthcare professionals
Clinical Trials Experience
Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.
Adverse reactions associated with Rythmol occur most frequently in the gastrointestinal, cardiovascular, and central nervous systems. About 20% of patients treated with Rythmol have discontinued treatment because of adverse reactions.
Adverse reactions reported for > 1.5% of 474 SVT patients who received Rythmol in U.S. clinical trials are presented in Table 1 by incidence and percent discontinuation, reported to the nearest percent.
Table 1: Adverse Reactions Reported for > 1.5% of SVT Patients
(N = 480)
|% of Pts. Who Discontinued|
|Nausea and/or Vomiting||11%||2.9%|
|Wide Complex Tachycardia||2%||1.9%|
In controlled trials in patients with ventricular arrhythmia, the most common reactions reported for Rythmol and more frequent than on placebo were
- unusual taste,
- first degree AV block,
- intraventricular conduction delay,
- nausea and/or vomiting, and
Headache was relatively common also, but was not increased compared to placebo. Other reactions reported more frequently than on placebo or comparator and not already reported elsewhere included
- second degree AV block,
- bundle branch block,
- loss of balance,
- congestive heart failure, and
Adverse reactions reported for ≥ 1% of 2,127 ventricular arrhythmia patients who received propafenone in U.S. clinical trials were evaluated by daily dose. The most common adverse reactions appeared dose-related (but note that most patients spent more time at the larger doses), especially
- nausea and/or vomiting,
- unusual taste,
- constipation, and
- blurred vision.
Some less common reactions may also have been dose-related such as
- first degree AV block,
- congestive heart failure,
- dyspepsia, and
Other adverse reactions included
In addition, the following adverse reactions were reported less frequently than 1% either in clinical trials or in marketing experience. Causality and relationship to propafenone therapy cannot necessarily be judged from these events.
Nervous System: Abnormal dreams, abnormal speech, abnormal vision, confusion, depression, memory loss, numbness, paresthesias, psychosis/mania, seizures (0.3%), tinnitus, unusual smell sensation, vertigo.
The following adverse reactions have been identified during post-approval use of Rythmol. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.
Gastrointestinal: A number of patients with liver abnormalities associated with propafenone therapy have been reported in post-marketing experience. Some appeared due to hepatocellular injury, some were cholestatic and some showed a mixed picture.
Some of these reports were simply discovered through clinical chemistries, others because of clinical symptoms including fulminant hepatitis and death. One case was rechallenged with a positive outcome.
Blood and Lymphatic System: Increased bleeding time
Immune System: lupus erythematosis
Nervous System: Apnea, coma
What drugs interact with Rythmol (propafenone)?
CYP2D6 and CYP3A4 Inhibitors
Drugs that inhibit CYP2D6 (such as desipramine, paroxetine, ritonavir, or sertraline) and CYP3A4 (such as ketoconazole, ritonavir, saquinavir, erythromycin, or grapefruit juice) can be expected to cause increased plasma levels of propafenone. The combination of CYP3A4 inhibition and either CYP2D6 deficiency or CYP2D6 inhibition with administration of propafenone may increase the risk of adverse reactions, including proarrhythmia. Therefore, simultaneous use of Rythmol with both a CYP2D6 inhibitor and a CYP3A4 inhibitor should be avoided.
Cimetidine: Concomitant administration of propafenone immediate release tablets and cimetidine in 12 healthy subjects resulted in a 20% increase in steady-state plasma concentrations of propafenone.
Fluoxetine: Concomitant administration of propafenone and fluoxetine in extensive metabolizers increased the S-propafenone Cmax and AUC by 39% and 50% and the R propafenone Cmax and AUC by 71% and 50%.
Quinidine: Small doses of quinidine completely inhibit the CYP2D6 hydroxylation metabolic pathway, making all patients, in effect, slow metabolizers.
Concomitant administration of quinidine (50 mg three times daily) with 150 mg immediate release propafenone three times daily decreased the clearance of propafenone by 60% in extensive metabolizers, making them slow metabolizers.
Steady-state plasma concentrations more than doubled for propafenone, and decreased 50% for 5-OH-propafenone. A 100 mg dose of quinidine tripled steady state concentrations of propafenone. Avoid concomitant use of propafenone and quinidine.
Rifampin: Concomitant administration of rifampin and propafenone in extensive metabolizers decreased the plasma concentrations of propafenone by 67% with a corresponding decrease of 5-OH-propafenone by 65%.
The concentrations of norpropafenone increased by 30%. In slow metabolizers, there was a 50% decrease in propafenone plasma concentrations and increased the AUC and Cmax of norpropafenone by 74% and 20%, respectively.
Urinary excretion of propafenone and its metabolites decreased significantly. Similar results were noted in elderly patients: Both the AUC and Cmax propafenone decreased by 84%, with a corresponding decrease in AUC and Cmax of 5-OH-propafenone by 69% and 57%.
Concomitant use of propafenone and digoxin increased steady-state serum digoxin exposure (AUC) in patients by 60% to 270%, and decreased the clearance of digoxin by 31% to 67%. Monitor plasma digoxin levels of patients receiving propafenone and adjust digoxin dosage as needed.
The concomitant administration of propafenone and warfarin increased warfarin plasma concentrations at steady state by 39% in healthy volunteers and prolonged the prothrombin time (PT) in patients taking warfarin. Adjust the warfarin dose as needed by monitoring INR (international normalized ratio).
Orlistat may limit the fraction of propafenone available for absorption. In post marketing reports, abrupt cessation of orlistat in patients stabilized on propafenone has resulted in severe adverse events including convulsions, atrioventricular block and acute circulatory failure.
Concomitant use of propafenone and propranolol in healthy subjects increased propranolol plasma concentrations at steady state by 113%. In 4 patients, administration of metoprolol with propafenone increased the metoprolol plasma concentrations at steady state by 100% to 400%. The pharmacokinetics of propafenone was not affected by the coadministration of either propranolol or metoprolol. In clinical trials using propafenone immediate release tablets, patients who were receiving beta-blockers concurrently did not experience an increased incidence of side effects.
No significant effects on the pharmacokinetics of propafenone or lidocaine have been seen following their concomitant use in patients. However, concomitant use of propafenone and lidocaine has been reported to increase the risks of central nervous system side effects of lidocaine.
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Related Disease Conditions
An arrhythmia is an abnormal heart rhythm. With an arrhythmia, the heartbeats may be irregular or too slow (bradycardia), to rapid (tachycardia), or too early. When a single heartbeat occurs earlier than normal, it is called a premature contraction.
Atrial Flutter vs. Atrial Fibrillation
Atrial flutter and atrial fibrillation (AFib) are two types of a heart problem called atrial tachycardia. Both of these conditions involve the heart's electrical activity, but they are not the same disease. Both diseases are serious and need medical treatment. Common symptoms of these diseases are similar and include: Fatigue Blurry vision Lightheadedness Palpitations Feeling like you may faint Serious symptoms of both conditions are similar and include: Fainting Sweating Severe shortness of breath Chest pain Atrial flutter and AFib are heart conditions that require medical diagnosis (ECG) and treatment by a doctor or other medical health-care professional.
Atrial Fibrillation (AFib) Treatment Drugs
Atrial fibrillation (AFib) is a heart rhythm disorder that causes irregular and often rapid heartbeat. The medications to treat AFib include beta-blockers, blood thinners, and heart rhythm drugs. Atrial fibrillation drugs can cause serious side effects like seizures, vision changes, shortness of breath, fainting, other abnormal heart rhythms, excessive bleeding while coughing or vomiting, blood in the stool, and bleeding into the brain.
Atrial Fibrillation (AFib)
Atrial fibrillation (AF or AFib) is an abnormality in the heart rhythm, which involves irregular and often rapid beating of the heart. Symptoms may include heart palpitations, dizziness, fainting, fatigue, shortness of breath, and chest pain. Atrial fibrillation treatment may include medication or procedures like cardioversion or ablation to normalize the heart rate.
Atrial Fibrillation vs. Ventricular Fibrillation (AFib vs VFib Symptoms, ECG Strips)
Atrial fibrillation (AF or AFib) is an abnormality in the heart rhythm which involves irregular and often rapid beating of the heart. Symptoms may include heart palpitations, dizziness, fainting, fatigue, shortness of breath, and chest pain. Atrial fibrillation treatment may include medication or procedures like cardioversion or ablation to normalize the heart rate. Atrial fibrillation (AFib) and ventricular fibrillation (VFib) are problems with the heart that cause abnormal heart rhythms. Causes of these heart conditions include, heart disease, drugs and medications, excessive alcohol consumption, high cholesterol, advancing age, a diet that contains high levels of animal meat (fat), high blood pressure, stress, stimulants like caffeine, nicotine. Ventricular fibrillation is the more serious of the conditions because if it isn't treated immediately the person will likely die. Symptoms of AFib are confusion, anxiety, fatigue, a fluttering in the chest, and the feeling that you may pass out or faint. Atrial fibrillation is treated with medications, cardioversion therapy, and surgery. If a person with ventricular fibrillation does not seek medical help immediately they will mostly likely suffer from sudden cardiac arrest or sudden death.
Atrial Fibrillation (AFib) Symptoms and Signs
Atrial fibrillation or AFib is a type of heart rhythm abnormality. Early warning signs and symptoms of atrial fibrillation include chest pain, palpitations, shortness of breath, and lightheadedness. Treatment for atrial fibrillation includes medical procedures, surgery, and medication.
Paroxysmal Supraventricular Tachycardia (PSVT)
Paroxysmal supraventricular tachycardia (PSVT) is an abnormal conduction of electricity in particular areas of the heart. PSVT was referred to at one time as paroxysmal atrial tachycardia or PAT, however, the term PAT is reserved for as specific heart condition. Symptoms of PSVT include weakness, shortness of breath, chest pressure, lightheadedness, and palpitations. PSVT is treated with medications or procedures that return the heart to its normal electrical pattern.
POTS (POT Syndrome, Postural Orthostatic Tachycardia Syndrome)
POT syndrome (POTS, postrual orthostatic tachycardia syndrome) is a nervous system disorder that causes lightheadedness and fainting when a person stands up. Treatment may include increasing blood volume and regulating circulatory problems that are responsible for the disorder.
What are the Most Common Causes of Atrial Fibrillation?
Atrial fibrillation (AF) is an abnormal heart rhythm characterized by an irregular and fast heartbeat. The upper chambers of the heart (atria) beat chaotically, and can cause pooling and clotting of blood in the atria, instead of it emptying into the lower chamber (ventricles). AF can lead to stroke, heart failure, blood clots, and heart-related complications. Atrial fibrillation is classified into three types: Paroxysmal atrial fibrillation, persistent atrial fibrillation, and long-standing persistent atrial fibrillation.
Treatment & Diagnosis
Medications & Supplements
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
Professional side effects and drug interactions sections courtesy of the U.S. Food and Drug Administration.