• Antiarrhythmic

Encainide ( en-KAY-nide) belongs to the group of medicines known as antiarrhythmics. It is used to correct irregular heartbeats to a normal rhythm.

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

There is a chance that encainide may cause new heart rhythm problems when it is used. Since it has been shown to cause severe problems in some patients, it is only used to treat serious heart rhythm problems. Discuss this possible effect with your doctor.

This medicine is available only from your doctor in the following dosage form:

Oral
• Capsules

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 encainide, the following should be considered:

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

Pregnancy—Encainide has not been studied in pregnant women. However, this medicine has not been shown to cause birth defects or other problems in animal studies, but has been shown to reduce fertility in rats. Before taking encainide, make sure your doctor knows if you are pregnant or if you may become pregnant.

Breast-feeding—Encainide passes into the milk of some animals and may also pass into the milk of humans. However, this medicine has not been reported to cause problems in nursing babies.

Children—Studies on this medicine have been done only in adult patients. Therefore, be sure to discuss with your doctor the use of this medicine in children.

Older adults—Many medicines have not been tested 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 about the use of encainide in the elderly.

• Diabetes mellitus—Encainide may raise blood sugar levels

• Kidney disease—Effects of encainide may be increased because of slower removal from the body

• Liver disease—Effects of encainide may be changed

• Recent heart attack—Risk of irregular heartbeats may be increased

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

Take encainide exactly as directed by your doctor, even though you may feel well. Do not take more or less of it 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 encainide 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 encainide. If your dose is different, do not change it unless your doctor tells you to do so.

• For oral dosage form (capsules):
  • For irregular heartbeat:
    • Adults—25 to 50 milligrams (mg) every eight hours.
    • Children—Use and dose must be determined by your doctor.

Missed dose—

If you miss a dose of encainide 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.

Encainide 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:

• More common
  • Chest pain;  fast or irregular heartbeat  
  
  

• Rare
  • Shortness of breath;  swelling of feet or lower legs;  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:

• Less common
  • Blurred or double vision;  dizziness ;  headache;  nausea;  pain in arms or legs;  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.