An irregular heartbeat is an arrhythmia (also called dysrhythmia). Heart rates can also be irregular. A normal heart rate is 50 to 100 beats per minute. Arrhythmias and abnormal heart rates don't necessarily occur together. Arrhythmias can occur with a normal heart rate, or with heart rates that are slow (called bradyarrhythmias -- less than 50 beats per minute). Arrhythmias can also occur with rapid heart rates (called tachyarrhythmias -- faster than 100 beats per minute). In the United States, more than 850,000 people are hospitalized for an arrhythmia each year.
Arrhythmias may be caused by many different factors, including:
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Norpace®
(disopyramide phosphate) Capsules
Norpace®CR
(disopyramide phosphate) Extended-Release Capsules
Norpace (disopyramide phosphate) is an anti-arrhythmic drug available for oral administration in immediate-release and controlled-release capsules containing 100 mg or 150 mg of disopyramide base, present as the phosphate. The base content of the phosphate salt is 77.6%. The structural formula of Norpace (disopyramide phosphate) is:
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α-[2-(diisopropylamino) ethyl]-α-phenyl-2-pyridineacetamide phosphate
Norpace (disopyramide phosphate) is freely soluble in water, and the free base (pKa 10.4) has an aqueous solubility of 1mg/ml. The chloroform: water partition coefficient of the base is 3.1 at pH 7.2.
Norpace (disopyramide phosphate) is a racemic mixture of d- and l- isomers. This drug is not chemically related to other anti-arrhythmic drugs.
Norpace (disopyramide phosphate) CR (controlled-release) capsules are designed to afford a gradual and consistent release of disopyramide. Thus, for maintenance therapy, Nor-pace CR provides the benefit of less-frequent dosing (every 12 hours) as compared with the every-6-hour dosage schedule of immediate-release Norpace (disopyramide phosphate) capsules.
Inactive ingredients of Norpace (disopyramide phosphate) include corn starch, edible ink, FD&C Red No. 3, FD&C Yellow No. 6, gelatin, lactose, talc, and titanium dioxide; the 150-mg capsule also contains FD&C Blue No.1.
Inactive ingredients of Norpace (disopyramide phosphate) CR include corn starch, D&C Yellow No. 10, edible ink, ethylcellulose, FD&C Blue No. 1, gelatin, shellac, sucrose, talc, and titanium dioxide; the 150-mg capsule also contains FD&C Red No. 3 and FD&C Yellow No. 6.
If you experience any of the following serious side effects, stop taking disopyramide and seek emergency medical attention:
Other, less serious side effects may be more likely to occur. Talk to your...
Read All Potential Side Effects and See Pictures of Norpace »
Before taking disopyramide, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.
Before using this medication, tell your doctor or pharmacist your medical history, especially of: diabetes, glaucoma, kidney disease, liver problems, myasthenia gravis, urinary problems (such as due to enlarged prostate, urinary retention).
This drug may rarely make you dizzy. Do not drive, use machinery, or do any activity that requires alertness until you are sure you can perform such activities safely. Limit alcoholic beverages.
Before having surgery, tell your doctor or dentist that you are using this...
Last reviewed on RxList: 7/17/2008
This monograph has been modified to include the generic and brand name in many instances.
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