DrugindexOnline^{2nd edition}

Generic name: Disopyramide phosphate
Brand names: Norpace, Norpace CR

Why is Norpace prescribed?

Norpace is used to treat severe irregular heartbeat. It relaxes an overactive heart and improves the efficiency of the heart's pumping action.

Most important fact about Norpace

Do not stop taking Norpace without first consulting your doctor. Stopping suddenly can cause serious changes in heart function.

How should you take Norpace?

Be sure to take Norpace exactly as prescribed.

Norpace may cause dry mouth. For temporary relief suck on a hard candy, chew gum, or melt ice chips in your mouth.

--If you miss a dose...

Take it as soon as you remember, if the next dose is 4 or more hours away. If you do not remember until later, skip the dose you missed and go back to your regular schedule. Do not take 2 doses at once.

--Storage instructions...

Store at room temperature.

What side effects may occur?

Side effects cannot be anticipated. If any develop or change in intensity, inform your doctor as soon as possible. Only your doctor can determine if it is safe for you to continue taking Norpace.

• More common side effects may include:
  Abdominal pain, aches and pains, bloating and gas, blurred vision, constipation, dizziness, dry eyes, nose, and throat, dry mouth, fatigue, headache, inability to urinate, increased urinary frequency and urgency, muscle weakness, nausea, vague feeling of bodily discomfort

Why should Norpace not be prescribed?

This drug should not be used if the output of your heart is inadequate (cardiogenic shock) or if you are sensitive to or have ever had an allergic reaction to Norpace.

Norpace can be used for only certain types of irregular heartbeat, and must not be used for others.

Special warnings about Norpace

If you have structural heart disease, inflammation of the heart muscle, or other heart disorders, use Norpace with extreme caution.

Norpace may cause or worsen congestive heart failure and can cause severe low blood pressure. If you have a history of heart failure, your doctor will carefully monitor your heart function while you are taking Norpace.

Norpace can cause low blood sugar (hypoglycemia), especially if you have congestive heart failure; poor nutrition; or kidney, liver, or other diseases; or if you are taking beta-blocking blood pressure drugs such as Tenormin or drinking alcohol.

Your doctor will prescribe Norpace along with other heart-regulating drugs, such as quinidine, procainamide, encainide, flecainide, propafenone, and propranolol, only if the irregular rhythm is considered life-threatening and other antiarrhythmic medication has not worked.

If you have the eye condition called glaucoma, myasthenia gravis, or difficulty urinating (particularly if you have a prostate condition), use Norpace cautiously.

You will take lower dosages if you have liver or kidney disease.

Your doctor should check your potassium levels before starting you on Norpace. Low potassium levels may make Norpace ineffective; high levels may increase its toxic effects.

Possible food and drug interactions when taking Norpace

Avoid alcoholic beverages while taking Norpace.

If Norpace is taken with certain other drugs, the effects of either could be increased, decreased, or altered. It is especially important to check with your doctor before combining Norpace with the following:

Clarithromycin (Biaxin)
Drugs that inhibit the breakdown of other drugs by the liver, including Tagamet
Erythromycin (Eryc, Ery-Tab, PCE)
Other heart-regulating drugs such as quinidine (Quinidex), procainamide (Procan SR), lidocaine (Xylocaine), propranolol (Inderal), Verapamil (Calan)
Phenytoin (Dilantin)
Troleandomycin (Tao)

Special information if you are pregnant or breastfeeding

The effects of Norpace during pregnancy have not been adequately studied. If you are pregnant or plan to become pregnant, inform your doctor immediately. Norpace appears in breast milk and may affect a nursing infant. If Norpace is essential to your health, your doctor may advise you to discontinue breastfeeding until your treatment with Norpace is finished.

Recommended dosage

Treatment with Norpace should be started in the hospital.

ADULTS

Your doctor will adjust your dosage according to your own response to, and tolerance of, Norpace or Norpace CR.

The usual dosage range of Norpace and Norpace CR is 400 milligrams to 800 milligrams per day, divided into smaller doses.

The recommended dosage for most adults is 600 milligrams per day, divided into smaller doses (either 150 milligrams every 6 hours for immediate-release Norpace or 300 milligrams every 12 hours for Norpace CR).

For those who weigh less than 110 pounds, the recommended dosage is 400 milligrams per day, divided into smaller doses (either 100 milligrams every 6 hours for immediate-release Norpace or 200 milligrams every 12 hours for Norpace CR.

For people with severe heart disease, the starting dose will be 100 milligrams of immediate-release Norpace every 6 to 8 hours. Your doctor will adjust the dosage gradually and watch you closely for any signs of low blood pressure or heart failure.

For people with moderately reduced kidney or liver function, the dosage is 400 milligrams per day, divided into smaller doses (either 100 milligrams every 6 hours for immediate-release Norpace or 200 milligrams every 12 hours for Norpace CR). This dosage is also recommended for people with glaucoma (high pressure in the eye), urinary retention, or an enlarged prostate gland, in the event they develop side effects.

For those who have severe kidney impairment, the dosage of immediate-release Norpace is 100 milligrams; the times will vary with the individual as determined by your doctor.

Norpace CR is not recommended for people with severe kidney disease.

CHILDREN

Dosage in children to age 18 is based on body weight. The total daily dosage should be divided into equal doses taken orally every 6 hours or at intervals that are best for the individual.

Overdosage

Any medication taken in excess can have serious consequences. An overdose of Norpace can be fatal. If you suspect an overdose, seek medical treatment immediately.

• The symptoms of Norpace overdose may include:
  Cessation of breathing, irregular heartbeat, loss of consciousness, low blood pressure, slow heartbeat, worsening of congestive heart failure