Rythmol SR Side Effects

Generic Name: propafenone,propafenone hydrochloride

Please note - some side effects for Rythmol SR may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

Side Effects of Rythmol SR - for the Consumer

Rythmol SR Sustained-Release Capsules

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Rythmol SR Sustained-Release Capsules:

Change in taste; constipation; diarrhea; dizziness; drowsiness; dry mouth; gas; headache; light-headedness; nausea; tiredness.

Seek medical attention right away if any of these SEVERE side effects occur when using Rythmol SR Sustained-Release Capsules:

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); black, tarry stools; blood in the urine; burning, numbness, or tingling; change in the amount of urine produced or painful urination; chest pain; confusion; fainting; fast or slow heartbeat; fever, chills, or sore throat; hearing problems; mental or mood problems (eg, anxiety, depression); muscle weakness; new or worsened irregular heartbeat; numbness of an arm or leg; one-sided weakness; pain, swelling, or redness of the calf or legs; ringing in the ears; severe or persistent dizziness, tiredness, or weakness; severe stomach or back pain; shortness of breath; slurred speech; sudden, severe headache; sudden weight gain; swelling of the hands or feet; tremor; trouble sleeping; unusual bruising or bleeding; vomiting; vision problems (eg, blurred vision); wheezing.

This is not a complete list of all side effects that may occur. If you have questions about side effects, contact your health care provider. Call your doctor for medical advice about side effects. To report side effects to the appropriate agency, please read the Guide to Reporting Problems to FDA.

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Rythmol SR Side Effects - for the Professional

Rythmol SR

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.

The data described below reflect exposure to Rythmol SR 225 mg twice daily in 126 patients, to Rythmol SR 325 mg twice daily in 135 patients, to Rythmol SR 425 mg twice daily in 136 patients, and to placebo in 126 patients for up to 39 weeks (mean 20 weeks) in a placebo-controlled trial (RAFT) conducted in the US. The most commonly reported adverse events with propafenone (>5% and greater than placebo) excluding those not reasonably associated with the use of the drug or because they were associated with the condition being treated, were dizziness, palpitations, chest pain, dyspnea, taste disturbance, nausea, fatigue, anxiety, constipation, upper respiratory tract infection, edema, and influenza.  The frequency of discontinuation due to adverse events was 17%, and the rate was highest during the first 14 days of treatment.

Cardiac-related adverse events occurring in ≥ 2% of the patients in any of the RAFT propafenone SR treatment groups and more common with propafenone than with placebo, excluding those that are common in the population and those not plausibly related to drug therapy, included the following: angina pectoris, atrial flutter, AV block first degree, bradycardia, congestive cardiac failure, cardiac murmur, edema, dyspnea, rales, wheezing, and cardioactive drug level above therapeutic.

Propafenone prolongs the PR and QRS intervals in patients with atrial and ventricular arrhythmias. Prolongation of the QRS interval makes it difficult to interpret the effect of propafenone on the QT interval [see Clinical Pharmacology (12.2)].

Non-cardiac related adverse events occurring in ≥ 2% of the patients in any of the RAFT propafenone SR treatment groups and more common with propafenone than with placebo, excluding those that are common in the population and those not plausibly related to drug therapy, included the following: blurred vision, constipation, diarrhea, dry mouth, flatulence, nausea, vomiting, fatigue, weakness, upper respiratory tract infection, blood alkaline phosphatase increased, hematuria, muscle weakness, dizziness (excluding vertigo), headache, taste disturbance, tremor, somnolence, anxiety, depression, ecchymosis.

No clinically important differences in incidence of adverse reactions were noted by age or gender. Too few non-Caucasian patients were enrolled to assess adverse events according to race.

Adverse events occurring in 2% or more of the patients in any of the ERAFT [see Clinical Studies (14)] propafenone SR treatment groups and not listed above include the following: bundle branch block left, bundle branch block right, conduction disorders, sinus bradycardia, and hypotension.

Other adverse events reported with propafenone clinical trials not already listed elsewhere in the prescribing information include the following adverse events by body and preferred term.

Blood and Lymphatic System Disorders

Anemia, lymphadenopathy, spleen disorder, thrombocytopenia.

Cardiac Disorders

Unstable angina, atrial hypertrophy, cardiac arrest, coronary artery disease, extrasystoles, myocardial infarction, nodal arrhythmia, palpitations, pericarditis, sinoatrial block, sinus arrest, sinus arrhythmia, supraventricular extrasystoles, ventricular extrasystoles, ventricular hypertrophy.

Ear and Labyrinth Disorders

Hearing impaired, tinnitus, vertigo.

Eye Disorders

Eye hemorrhage, eye inflammation, eyelid ptosis, miosis, retinal disorder, visual acuity reduced.

Gastrointestinal Disorders

Abdominal distension, abdominal pain, duodenitis, dyspepsia, dysphagia, eructation, gastritis, gastroesophageal reflux disease, gingival bleeding, glossitis, glossodynia, gum pain, halitosis, intestinal obstruction, melena, mouth ulceration, pancreatitis, peptic ulcer, rectal bleeding, sore throat.

General Disorders and Administration Site Conditions

Chest pain, feeling hot, hemorrhage, malaise, pain, pyrexia.

Hepatobiliary disorders

Hepatomegaly.

Investigations

Abnormal heart sounds, abnormal pulse, carotid bruit, decreased blood chloride, decreased blood pressure, decreased blood sodium, decreased hemoglobin, decreased neutrophil count, decreased platelet count, decreased prothrombin level, decreased red blood cell count, decreased weight, glycosuria present, increased alanine aminotransferase, increased aspartate aminotransferase, increased blood bilirubin, increased blood cholesterol, increased blood creatinine, increased blood glucose, increased blood lactate dehydrogenase, increased blood pressure, increased blood prolactin, increased blood triglycerides, increased blood urea, increased blood uric acid, increased eosinophil count, increased gamma-glutamyltransferase, increased monocyte count, increased prostatic specific antigen, increased prothrombin level, increased weight, increased white blood cell count, ketonuria present, proteinuria present.

Metabolism and Nutrition Disorders

Anorexia, dehydration, diabetes mellitus, gout, hypercholesterolemia, hyperglycemia, hyperlipidemia, hypokalemia.

Musculoskeletal, Connective Tissue and Bone Disorders

Arthritis, bursitis, collagen-vascular disease, costochondritis, joint disorder, muscle cramps, muscle spasms, myalgia, neck pain, pain in jaw, sciatica, tendonitis.

Nervous System Disorders

Amnesia, ataxia, balance impaired, brain damage, cerebrovascular accident, dementia, gait abnormal, hypertonia, hypothesia, insomnia, paralysis, paresthesia, peripheral neuropathy, speech disorder, syncope, tongue hypoesthesia.

Psychiatric Disorders

Decreased libido, emotional disturbance, mental disorder, neurosis, nightmare, sleep disorder.

Renal and Urinary Disorders

Dysuria, nocturia, oliguria, pyuria, renal failure, urinary casts, urinary frequency, urinary incontinence, urinary retention, urine abnormal.

Reproductive System and Breast Disorders

Breast pain, impotence, prostatism.

Respiratory, Thoracic and Mediastinal Disorders

Atelectasis, breath sounds decreased, chronic obstructive airways disease, cough, epistaxis, hemoptysis, lung disorder, pleural effusion, pulmonary congestion, rales, respiratory failure, rhinitis, throat tightness.

Skin and Subcutaneous Tissue Disorders

Alopecia, dermatitis, dry skin, erythema, nail abnormality, petechiae, pruritus, sweating increased, urticaria.

Vascular Disorders

Arterial embolism limb, deep limb venous thrombosis, flushing, hematoma, hypertension, hypertensive crisis, hypotension, labile blood pressure, pallor, peripheral coldness, peripheral vascular disease, thrombosis.

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Side Effects by Body System - for Healthcare Professionals

General

The Cardiac Arrhythmia Suppression Trial (CAST) revealed significantly higher mortality associated with some class IC antiarrhythmic agents in patients with a recent history (more than six days but less than two years prior to study) of myocardial infarction and asymptomatic non-life-threatening ventricular arrhythmias relative to placebo (5.1% versus 2.3%). Use of propafenone in this context is potentially harmful.

The safety and tolerability of propafenone after long-term administration has been reported. After 14 months, 60% of patients discontinued therapy, but only 15% discontinued therapy due to side effects. Overall, 59% of patients experienced at least 1 side effect, and the incidence was related to dose and age > 65 years. The overall incidence of side effects was not related to structural heart disease. However, cardiovascular toxicity including arrhythmia aggravation, heart failure, and serious conduction disturbances occurred more often in those with heart disease (20% vs. 13%).

Cardiovascular

Accelerated ventricular tachycardias refractory to overdrive pacing in patients on propafenone, who had arrhythmias previously responsive to overdrive pacing, have been reported.

Cardiovascular side effects may be serious. Two to four percent of patients have experienced a proarrhythmic effect. Propafenone slows conduction throughout the myocardial conduction system with very little effect on repolarization, resulting in a prolonged PR interval and QRS complex. Cases of bradycardia, sinus pauses and arrest, accelerated reentrant tachycardia, AV block, and ventricular tachycardia, including torsades de pointes, have been reported.

Propafenone has negative inotropic activity. Preexisting congestive heart failure has been aggravated in 9% of patients and new congestive heart failure induced in 5% of patients.

Nervous system

A 68 year-old man with ocular myasthenia gravis developed generalized myasthenia with ptosis, diplopia, dysarthria, dysphagia, and limb weakness within hours after beginning propafenone 450 mg per day. It is believed that propafenone, by blocking fast sodium channels, may interfere with the generation of propagation of the motor end-plate potential.

Nervous system side effects have included dizziness in 7%, headaches in 5%, ataxia in 1% to 3%, and fatigue in less than 1% of patients. Rare cases of exacerbation of myasthenia gravis and peripheral neuropathy have been associated with the use of propafenone.

Gastrointestinal

Gastrointestinal side effects have included general gastrointestinal upset in 3%, constipation in 4%, a metallic taste in 9%, and nausea or vomiting in approximately 2% of patients.

Respiratory

Respiratory side effects have included dyspnea, wheezing, and bronchoconstriction. These side effects have not exclusively been reported in patients with preexisting reactive airways disease.

Limited data indicate that the plasma concentration of propafenone is not correlated with respiratory complaints, although caution is recommended particularly when daily doses exceed 450 mg. Propafenone is associated with a significant decrease in the average dose of methacholine required to reduce the forced expiratory volume in 1 second (FEV1) by 20% and an increase in the use of beta-agonist inhalers in patients with asthma.

A case of wheezing and decreased expiratory flow rates has been associated with propafenone in a 50-year-old woman with no history of reactive airways disease and who had previously received atenolol and metoprolol without problems.

Hematologic

Hematologic side effects have been rare. A meta-analysis of all adverse drug events associated with propafenone yielded 4 cases of agranulocytosis. The reported rate is 1 case per 10,000 prescriptions per year. Anemia, granulocytopenia, increased bleeding time, leukopenia, purpura, and thrombocytopenia have occurred.

Profound neutropenia associated with bone marrow evidence of myeloid injury has been reported in at least 4 cases. Each patient recovered completely within 7 to 30 days after drug withdrawal.

Hepatic

Propafenone associated liver injury appears to be secondary to hepatocellular injury, cholestasis, or a combination of these. In some cases an allergic reaction has been suspected, while in at least one case, an idiosyncratic toxicity of propafenone metabolites in the biliary epithelial cells was suspected. There are no known fatalities or cases in which the drug had to be discontinued due to elevated liver function tests.

Hepatic side effects been reported. The overall incidence of hepatotoxicity is estimated to be 0.1% to 0.2%.

Immunologic

Immunologic side effects including the rare development of a lupus-like syndrome have been reported in at least two cases. An elevated ANA titer has been reported in 0.7% of patients.

A 63-year-old woman with hypertension, coronary artery disease, and ventricular tachycardia developed a facial photosensitive rash, generalized erythema, and an elevated ANA titer in a homogenous and speckled pattern within 2 months after beginning propafenone 300 mg every 8 hours. The clinical and laboratory abnormalities resolved within 1 month of drug discontinuation and reappeared upon rechallenge with propafenone.

Psychiatric

A 39-year-old woman with a history of congestive heart failure and symptomatic premature ventricular depolarizations developed paresthesias, insomnia, paranoia, hallucinations, and frank psychosis within 24 hours after starting propafenone 300 mg every 12 hours. The syndrome resolved within 2 to 3 days after discontinuation of the drug and institution of haloperidol. The patient subsequently did well off of haloperidol, on an alternative antiarrhythmic agent.

A 61-year-old man with a history of sick sinus syndrome, chronic atrial fibrillation, and premature ventricular depolarizations developed amnesia and disorientation within six days after starting propafenone. His mental status deterioration resolved within six to seven hours after discontinuing therapy. Comparable adverse effects have been associated with an analogous agent, propranolol.

Psychiatric abnormalities have been limited to a case of frank psychosis and a case of global amnesia.

Ocular

Ocular side effects of blurred vision (4%), abnormal vision(2%), and eye irritation (less than 1%) have been reported.

Dermatologic

Dermatologic side effects including at least one case of acute generalized exanthematous pustulosis, which resolved within 3 days after discontinuation of propafenone, has been reported.

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