Moricizine (By mouth)


Moricizine (mor-I-si-zeen)

Treats severe heart rhythm problems.

Brand Name(s)

There may be other brand names for this medicine.

When This Medicine Should Not Be Used

You should not be given this medicine if you have had an allergic reaction to moricizine. You should not be given this medicine if you have certain serious heart problems (second- or third-degree AV block, right bundle branch block with left hemiblock). The manufacturer stopped making this drug on August 28, 2007, because of a low market demand. Talk to your doctor about changing to a different medicine. Do not stop taking your medicine without talking to your doctor.

How to Use This Medicine


  • Your doctor will tell you how much of this medicine to use and how often. Your dose may need to be changed several times in order to find out what works best for you. Do not use more medicine or use it more often than your doctor tells you to.

If a dose is missed:

  • This medicine needs to be given on a fixed schedule. If you miss a dose or forget to use your medicine, call your doctor or pharmacist for instructions.

How to Store and Dispose of This Medicine

  • Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light.
  • Keep all medicine away from children and never share your medicine with anyone.
  • Ask your pharmacist, doctor, or health caregiver about the best way to dispose of any outdated medicine or medicine no longer needed.

Drugs and Foods to Avoid

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

  • Make sure your doctor knows if you are also using the stomach medicine cimetidine (Tagamet®), or if you are also using a beta-blocker blood pressure medicine, such as propranolol. Make sure your doctor knows if you are also using an medicine for breathing problems, such as theophylline.
  • Make sure your doctor knows if you are also using a blood thinner medicine, such as warfarin (Coumadin®). Make sure your doctor knows if you are also using other medicine for heart rhythm problems. These medicines include amiodarone, disopyramide, dofetilide, flecainide, procainamide, propafenone, quinidine, sotalol, Betapace®, Cardioquin®, Cordarone®, Norpace®, Procanbid®, Quinaglute®, Rythmol®, or Tambocor®, and Tikosyn®.

Warnings While Using This Medicine

  • Make sure your doctor knows if you are pregnant or breast feeding, or if you have a condition called "sick sinus syndrome". Make sure your doctor knows if you have unusually high or low levels of calcium or magnesium in your blood (hyperkalemia or hypokalemia, or hypomagnesemia).
  • Make sure your doctor knows if you have severe kidney or liver problems. Make sure your doctor knows if you have an artificial pacemaker.
  • Your doctor will need to check your progress at regular visits while you are using this medicine. Be sure to keep all appointments.
  • If your symptoms do not improve or if they get worse, call your doctor.

Possible Side Effects While Using This Medicine

Call your doctor right away if you notice any of these side effects:

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
  • Worsened heart rhythm problems.

If you notice these less serious side effects, talk with your doctor:

  • Bleeding or bruising easily.
  • Blurred vision, or double vision, rapid eye movements you cannot control, or eye pain or swelling.
  • Chest pain.
  • Cold sweat and bluish-skin.
  • Dark-colored urine or pale stools.
  • Decrease in how often or how much you urinate, trouble controlling your bladder, or painful urination.
  • Decrease in your sexual desires, or trouble having or keeping an erection.
  • Difficulty speaking.
  • Dry, itchy, or red skin, or rash.
  • Dry mouth, swollen lips or tongue, or trouble swallowing.
  • Feeling unusually tired or weak.
  • Feeling unusually anxious, confused, nervous, or sad, or trouble remembering things.
  • Fever, chills, or sweating.
  • Headache, dizziness, lightheadedness, or fainting.
  • Loss of appetite.
  • Loss of your sense of touch.
  • Muscle or bone pain, or low back pain.
  • Nausea, upset stomach, extra gas, vomiting, or diarrhea.
  • Numbness or tingling in your feet, hands, or other body parts.
  • Problems walking or controlling your muscle movement.
  • Ringing in your ears.
  • Seeing or hearing things that are not there.
  • Shaking or twitching in your hands or other parts of your body, or seizures.
  • Shortness of breath or trouble breathing, cough, or coughing up blood.
  • Swelling in your hands, feet, or ankles.
  • Trouble breathing.
  • Yellowing of your skin or the whites of your eyes.

If you notice other side effects that you think are caused by this medicine, tell your doctor

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088

Version Info

  • Last Reviewed on 06/12/2013

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission ( URAC's accreditation program is an independent audit to verify that A.D.A.M. follows rigorous standards of quality and accountability. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial policy, editorial process and privacy policy. A.D.A.M. is also a founding member of Hi-Ethics and subscribes to the principles of the Health on the Net Foundation (

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- 2013 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.