Generic name: Disopyramide phosphate.

Other brand names: Napamide, Norpace CR.

Norpace is an anti-arrhythmic. It corrects irregular heartbeats and helps produce a more normal rhythm by altering nerve impulses in the heart. 

Quick Facts About Norpace


Used to treat severe irregular heartbeat.

Norpace Dosage

Take exactly as prescribed. Comes in immediate and suspended release forms. Do not discontinue use unless directed by your doctor; can cause serious changes in heart function.

  • Usual adult dose: ranges from 400 to 800 milligrams per day divided into smaller doses. For those weighing less than 110 pounds — 400 milligrams per day divided into smaller doses. For those with severe heart disease — 100 milligrams of immediate release every 6 to 8 hours. For those with moderately reduced kidney or liver function — 400 milligrams per day divided into smaller doses. For those with severe kidney impairment — 100 milligrams per day. Not recommended if you have severe kidney disease.
  • Usual child dose: for children under 18 years — based on body weight and divided into equal doses taken orally every 6 hours or at intervals prescribed for the individual’s specific needs.
  • Missed dose: take as soon as possible, if next dose is more than 4 hours away. Otherwise, skip missed dose; go back to regular schedule. Do not double doses.

Norpace Side Effects

Overdose symptoms:

apnea (no breathing), loss of consciousness, loss of spontaneous respiration. If you suspect an overdose, immediately seek medical attention.

Overdose may be fatal.

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

Less common or rare Norpace side effects: breast development in males, chest pain, congestive heart failure, depression, diarrhea, difficulty breathing, difficulty sleeping, fainting, fever, itching, impotence, low blood pressure, low blood sugar (hypoglycemia), nervousness, numbness or tingling, painful urination, rash, psychosis, shortness of breath, skin diseases, swelling due to fluid retention, vomiting, weight gain, yellow eyes and skin.


Inform your doctor before combining Norpace with:

heart-regulating medications such as lidocaine (Xylocaine), procainamide (Procan SR), propranolol (Inderal), quinidine (Quinidex), and verapramil (Calan); phenytoin (Dilantin). Doctor will prescribe other heart-regulating medications such as quinidine, procainamide, encainide, flecainide, propafenone, and propranolol with Norpace if the irregular rhythm is considered life-threatening; or if other anti-arrhythmic medications have not worked.

Avoid alcohol during Norpace therapy. 

Special Cautions

If pregnant or planning to become pregnant, inform your doctor immediately. Appears in breast milk; could affect a nursing infant.

No special precautions apply to seniors.

Follow doctor’s instructions carefully for children.

  • Should not use if the output of your heart is inadequate, or if sensitive to or allergic to Norpace.
  • Your doctor will advise usage based on a specific type of irregular heartbeat.
  • Use with extreme caution if you have structural heart disease, inflammation of the heart muscle, or other heart disorders; glaucoma; myasthenia gravis; or difficulty urinating.
  • Doctor should check potassium levels before Norpace therapy begins; if you have low levels, medication may be ineffective; with high levels, may be toxic.
  • May worsen or cause congestive heart failure; doctor will monitor your heart if you have a history of heart failure.
  • At risk for low blood sugar if you have congestive heart failure, poor nutrition, kidney or liver diseases, if you are taking beta-blockers, or if you drink alcohol during Norpace therapy.

Note: provides accurate and independent information prescription pills, over-the-counter medicines and natural products. This material is provided for educational purposes only and is not intended for medical advice, diagnosis or treatment. If you have questions about  dosage, or Norpace side effects, please contact your healthcare provider