In the U.S.—

In Canada—

• Antiarrhythmic

Propafenone ( proe-pa-FEEN-none) belongs to the group of medicines known as antiarrhythmics. It is used to treat abnormal heart rhythms.

Propafenone produces its helpful effects by slowing nerve impulses in the heart and making the heart tissue less sensitive.

There is a chance that propafenone may cause new heart rhythm problems or make worse those that already exist. Since similar medicines have been shown to cause severe problems in some patients, propafenone is only used to treat serious heart rhythm problems. Discuss this possible effect with your doctor.

This medicine is available only with your doctor's prescription, in the following dosage form:

Oral
• Tablets (U.S. and Canada)

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

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to propafenone. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy—Propafenone has not been studied in pregnant women. Although this medicine has not been shown to cause birth defects in animal studies, it has been shown to reduce fertility in monkeys, dogs, and rabbits. In addition, in rats it caused decreased growth in the infant and deaths of mothers and infants. Before taking propafenone, make sure your doctor knows if you are pregnant or if you may become pregnant.

Breast-feeding—Propafenone passes into breast milk. Because of the potential for problems in the nursing infant, propafenone is generally not recommended in mothers who are breast-feeding.

Children—Propafenone can cause serious side effects in any patient. Therefore, it is especially important that you discuss with the child's doctor the good that this medicine may do as well as the risks of using it.

Older adults—Many medicines have not been studied specifically in older people. Therefore, it may not be known whether they work exactly the same way they do in younger adults or if they cause different side effects or problems in older people. There is no specific information comparing use of propafenone in the elderly with use in other age groups.

Other medicines—Although certain medicines should not be used together at all, in other cases two different medicines 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 taking propafenone it is especially important that your health care professional know if you are taking either of the following:

• Digoxin (e.g., Lanoxin) or
• Warfarin (e.g., Coumadin)—Effects of these medicines may be increased when used with propafenone

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

• Bradycardia (unusually slow heartbeat)—There is a risk of further decreased heart function

• Congestive heart failure or other heart disease or
• Myasthenia gravis or
• Severe low blood pressure—Propafenone may make these conditions worse

• Electrolyte (i.e., potassium) disorders—Propafenone may worsen heart rhythm problems

• Kidney disease or
• Liver disease—Effects of propafenone may be increased because of slower removal from the body

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

Take propafenone 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 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 health care professional.

Dosing—

The dose of propafenone 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 propafenone. If your dose is different, do not change it unless your doctor tells you to do so:

• The number of tablets that you take depends on the strength of the medicine.
• For oral dosage forms (tablets):
  • Adults: 150 milligrams every eight 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 propafenone and remember within 4 hours, take it as soon as possible. However, if you do not remember until later, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Storage—

To store this medicine:

• Keep out of the reach of children.
• Store away from heat and direct light.
• Do not store in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down.
• Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.

It is important that your doctor check your progress at regular visits to make sure the medicine is working properly. This will allow changes to be made in the amount of medicine you are taking, if necessary.

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

Before having any kind of surgery (including dental surgery) or emergency treatment, tell the medical doctor or dentist in charge that you are taking this medicine.

Propafenone may cause some people to become dizzy or lightheaded. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are dizzy.

Along with its needed effects, a medicine 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 as soon as possible if any of the following side effects occur:

• Less common
  • Chest pain;  shortness of breath;  fast, irregular, or slow heartbeat, dizziness, and/or fainting ;  swelling of feet or lower legs;  weight gain 
  
  

• Rare
  • Chills, fever, and weakness;  joint pain ;  trembling or shaking 
  
  

Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if any of the following side effects continue or are bothersome:

• More common
  • Change in taste or bitter or metallic taste 
  
  

• Less common
  • Blurred vision;  constipation or diarrhea ;  dryness of mouth;  headache ;  nausea and/or vomiting;  skin rash;  unusual tiredness or weakness 
  
  

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