Tambocor

Oral Administration

May take with food

Flecainide is used to prevent certain types of life-threatening irregular heartbeats. Flecainide is in a class of medications called antiarrhythmics. It works by slowing electrical signals in the heart to stabilize the heart rhythm.

• Tambocor^®

Common Side Effects of Flecainide

Tell your doctor if any of the following side effects become severe or don't go away:

• Dizziness
• Headache
• Vision changes
• Difficulty focusing
• Mild nausea
• Weakness
• Uncontrollable shaking of a part of the body
• Stomach pain
• Constipation

Serious Side Effects of Flecainide

Tell your doctor right away if you experience any of the following serious side effects:

• Signs of anaphylaxis, a severe allergic reaction (hives, rash, itching, chest tightness, or swelling of the face, lips, tongue, or throat)
• Chest pain
• A fast, pounding, or irregular heartbeat
• Shortness of breath
• Extreme tiredness
• Severe nausea
• Loss of appetite
• Persistent cough with bloody mucus
• Swelling of the hands, feet, ankles, or lower legs
• Unusual bruising or bleeding
• Confusion
• Pain in the upper right part of the stomach
• Yellowing of the skin or eyes (jaundice)
• Flu-like symptoms
• Seizures

Flecainide comes as a tablet to take by mouth.

It's typically taken every 12 hours. Some people may take the medication every 8 hours.

Try to take flecainide around the same time each day.

Follow the instructions on your prescription label carefully. Don't take more or less flecainide than your doctor recommends.

Your first dose of flecainide may be given in a medical setting, so that your healthcare provider can monitor your response.

Flecainide Overdose

Symptoms of a flecainide overdose may include:

• Fainting
• Nausea
• Seizures
• Slow, fast, or irregular heartbeat
• Vomiting

If you suspect an overdose, contact a poison control center or emergency room immediately.

You can get in touch with a poison control center at 800-222-1222.

Missed Dose of Flecainide

If you miss a dose of flecainide, take it as soon as you remember.

But if it's almost time for your next dose, skip the missed dose and continue on your regular medication schedule.

Don't take extra medicine to make up for a missed dose of flecainide.

You should not use this medication if you are allergic to flecainide, or if you have certain heart conditions, especially "AV block" (unless you have a pacemaker).

Before using flecainide, tell your doctor if you have congestive heart failure, a heart condition called "sick sinus syndrome," an electrolyte imbalance, liver disease, kidney disease, if you have a pacemaker, or if you have had a heart attack within the past 2 years.

You will need to receive your first few doses of flecainide in a hospital setting in case the medication causes serious side effects. Your heart rate will be constantly monitored using an electrocardiograph or ECG (sometimes called an EKG). This machine measures electrical activity of the heart.

Call your doctor at once if you have a serious side effect such as weak pulse, slow breathing, fast or uneven heartbeat, feeling like you might pass out, feeling short of breath, swelling, rapid weight gain, confusion, extreme thirst, increased urination, muscle weakness, or jaundice (yellowing of the skin or eyes).

You will need to receive your first few doses of flecainide in a hospital setting in case the medication causes serious side effects. Your heart rate will be constantly monitored using an electrocardiograph or ECG (sometimes called an EKG). This machine measures electrical activity of the heart.

Take flecainide exactly as it was prescribed for you. Do not take the medication in larger amounts or for longer than recommended by your doctor. Follow the directions on your prescription label.

Your doctor may occasionally change your dose to make sure you get the best results from this medication.

To be sure this medication is helping your condition, your blood may need to be tested on a regular basis. Do not miss any scheduled appointments.

Store flecainide at room temperature away from moisture, heat, and light.

Take the missed dose as soon as you remember. If it is almost time for your next dose, wait until then to take the medicine and skip the missed dose. Do not take extra medicine to make up the missed dose.

Applies to flecainide: oral capsule extended release, oral tablet

Along with its needed effects, flecainide (the active ingredient contained in Tambocor) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

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

• Difficult or labored breathing
• dizziness, fainting, or lightheadedness
• fast, irregular, pounding, or racing heartbeat or pulse
• shortness of breath
• tightness in the chest
• wheezing

• Burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
• chest pain
• fainting
• feeling of warmth
• fever
• increased sweating
• partial or slight paralysis
• redness of the face, neck, arms, and occasionally, upper chest
• shakiness and unsteady walk
• shakiness in the legs, arms, hands, or feet
• swelling of the feet or lower legs
• trembling or shaking of the hands or feet
• unsteadiness, trembling, or other problems with muscle control or coordination

• Arm, back, or jaw pain
• black, tarry stools
• bleeding gums
• blood in the urine or stools
• blurred vision
• chest discomfort
• chest tightness or heaviness
• chills
• confusion
• convulsions
• cough
• decrease in the frequency of urination
• decrease in urine volume
• difficulty in passing urine (dribbling)
• difficulty with breathing
• dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
• frequent urination
• general feeling of discomfort or illness
• headache
• increased volume of pale, dilute urine
• nausea
• nervousness
• noisy breathing
• painful or difficult urination
• pinpoint red spots on the skin
• pounding in the ears
• sensation of pins and needles
• slow or fast heartbeat
• sore throat
• sores, ulcers, or white spots on the lips or in the mouth
• stabbing pain
• sweating
• swollen glands
• thickening of bronchial secretions
• troubled breathing
• unusual bleeding or bruising
• unusual tiredness or weakness
• yellow eyes or skin

Some side effects of flecainide may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may 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:

• Blurred vision or seeing spots

• Abdominal or stomach pain
• acid or sour stomach
• anxiety or mental depression
• belching
• constipation
• continuing ringing or buzzing or other unexplained noise in the ears
• depression
• diarrhea
• feeling of constant movement of self or surroundings
• general feeling of discomfort or illness
• hearing loss
• heartburn
• indigestion
• lack or loss of strength
• loss of appetite
• sensation of spinning
• sleepiness or unusual drowsiness
• sleeplessness
• skin rash
• stomach discomfort, upset, or pain
• trouble with sleeping
• unable to sleep
• weight loss

• Bloated
• change in color vision
• change in taste
• cracks in the skin
• decreased awareness or responsiveness
• decreased interest in sexual intercourse
• difficulty seeing at night
• difficulty with moving
• dry mouth
• excess air or gas in the stomach or intestines
• eye pain or irritation
• false or unusual sense of well-being
• feeling of unreality
• full feeling
• hair loss or thinning of the hair
• hives or welts
• inability to have or keep an erection
• increased sensitivity of the eyes to sunlight
• itching skin
• joint pain
• lack of feeling or emotion
• loss in sexual ability, desire, drive, or performance
• loss of heat from the body
• loss of memory
• muscle aching or cramping
• muscle pain or stiffness
• passing gas
• problems with memory
• red, swollen skin
• scaly skin
• sense of detachment from self or body
• severe sleepiness
• swollen joints
• swollen lips, mouth, or tongue
• uncaring uncontrolled eye movements

Applies to flecainide: oral tablet

General

The Cardiac Arrhythmia Suppression Trial (CAST) revealed significantly higher mortality associated with flecainide (the active ingredient contained in Tambocor) in patients with a recent history (more than six days but less than two years prior to study) of myocardial infarction (MI) and non-life-threatening ventricular ectopy relative to placebo (5.1% versus 2.3%). The risk of death relative to placebo in patients with a recent history of Q-wave MI and non-Q-wave MI is 8.7 and 1.7, respectively. Use of flecainide in this context is potentially harmful.

Side effects are more likely when plasma flecainide concentrations are greater than 1.0 mcg/mL.[Ref]

Cardiovascular

Risk factors for a proarrhythmic effect include underlying congenital or structural heart disease.

A case of "pseudoinfarction" has been reported in which flecainide (the active ingredient contained in Tambocor) induced a transient right bundle branch block with a focal block in the septal fibers of the left bundle branch system. An electrocardiogram (ECG) also revealed ST segment elevations and a Q-wave pattern, consistent with septal infarction. The patient did not have a myocardial infarction by enzyme studies, and the ECG abnormalities resolved after discontinuation of flecainide.

One patient with a history of ischemic congestive heart failure, myocardial infarction (MI), and ventricular arrhythmias developed profound cardiogenic shock without evidence of MI or a new or worsened ventricular arrhythmia. The associated serum flecainide concentration was 1.8 mcg/mL.[Ref]

Cardiovascular side effects including arrhythmias are the most serious side effects. Flecainide may cause or exacerbate arrhythmias in 1% of patients with preexisting paroxysmal supraventricular tachycardia and in 7% of patients with paroxysmal atrial fibrillation. Flecainide may also exacerbate arrhythmias in 7% to 13% of patients with preexisting sustained or nonsustained ventricular arrhythmias.

Flecainide-induced arrhythmias include sinus bradycardia or arrest in 2%, bundle branch blocks in 1%, increased premature ventricular depolarizations in 1%, ventricular tachycardia or fibrillation in 0.5%, and sudden death in 0.2% of patients. New ventricular arrhythmias have been reported in 3.4% of patients.

Flecainide may cause prolongation of the PR, QRS, and corrected QT intervals. Most of the QT interval prolongation is attributable to widening of the QRS complex rather than prolongation of the JT interval. Rare cases of torsades de pointes have been reported.

Exacerbation of congestive heart failure is rare and only occurs in about 0.5% and 9% of patients with preexisting supraventricular arrhythmias and ventricular arrhythmias, respectively. Hypotension is almost exclusively associated with intravenous administration of flecainide.[Ref]

Nervous system

Flecainide may exacerbate myasthenia gravis.

At least 6 cases of flecainide-induced peripheral neuropathy (sensory loss) have been reported and it appears to develop after prolonged use ( 2 to 10 years). Following discontinuation of flecainide (the active ingredient contained in Tambocor) therapy, symptoms (e.g., lower-extremity weakness and/or paresthesias, gait disturbance) resolved over 3 to 6 months. However, in some cases the neuropathy did not resolve after discontinuation of flecainide.[Ref]

Nervous system side effects, such as dizziness and visual disturbances (including blurred vision, decreased acuity, and scotomata) occur in 13% to 28% of patients who are taking flecainide doses of 400 mg per day. Transient headaches, asthenia, feelings of a thick tongue or lips, fatigue, paresthesias, and tremors have been reported in 2% to 10% of patients.[Ref]

Gastrointestinal

Gastrointestinal side effects include abdominal pain, nausea, and constipation in 1% to 4% of patients. Diarrhea occurs rarely.[Ref]

Musculoskeletal

Musculoskeletal side effects including weakness has been reported and may be more likely in patients with underlying muscular disorders.[Ref]

A 33-year-old woman with atrial fibrillation, mitral valve prolapse, and a congenital muscle fiber disproportion myopathy developed muscle weakness which partially resolved after flecainide dosage reduction and completely resolved after substitution of flecainide with other antiarrhythmic agents.[Ref]

Ocular

High performance liquid chromatographic analysis of excised corneal deposits in one patient revealed opacities with the same chromatographic characteristics of flecainide (the active ingredient contained in Tambocor) [Ref]

Ocular side effects are limited to rare cases of corneal deposits.[Ref]

Genitourinary

Genitourinary side effects including complaints of impotence are reported in 4% of patients. A case of urinary retention associated with flecainide (the active ingredient contained in Tambocor) has been reported.[Ref]

Class I antiarrhythmic agents such as flecainide have local anesthetic and anticholinergic properties which may rarely cause urinary retention.[Ref]

Respiratory

A case of reversible flecainide-induced pneumonitis was reported in a 61-year-old man with a remote history of pulmonary tuberculosis. A complete infectious disease work-up was negative. Serial bronchial-alveolar lavages and chest radiographs were consistent with a drug-induced process.[Ref]

Respiratory side effects are extremely rare.[Ref]

Hematologic

One patient developed leukopenia after 5 months of flecainide (the active ingredient contained in Tambocor) therapy. The leukopenia resolved after drug discontinuation and did not recur when flecainide was reinstituted. The leukopenia may have been due to a concurrent viral infection.[Ref]

Hematologic side effects are extremely rare.[Ref]

Hepatic

Hepatic side effects including enzyme concentration elevations have been reported in rare cases.[Ref]

Psychiatric

Psychiatric side effects including paranoid psychosis was reported in a 62-year-old patient receiving flecainide (the active ingredient contained in Tambocor) for the treatment of malignant neuropathic pain.[Ref]

Some side effects of Tambocor may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.