Antiarrhythmic drugs

Antiarrhythmic drugs are medicines that correct irregular or too fast heartbeats. Normally, the heart beats at a steady, even pace. The pace is controlledby electrical signals that begin in one part of the heart and quickly spreadthrough the whole heart. If something goes wrong with this control system, the result may be an irregular heartbeat, or an arrhythmia. Antiarrhythmic drugs correct irregular heartbeats, restoring the normal rhythm. If the heart isbeating too fast, these drugs will slow it down. By correcting these problems, antiarrhythmic drugs help the heart work more efficiently.

Antiarrhythmic drugs are available only with a physician's prescription and are sold in capsule, tablet, and injectable forms. Commonly used antiarrhythmic drugs are disopyramide (Norpace, Norpace CR), procainamide (Procan SR, Pronestyl, Pronestyl-SR), and quinidine (Cardioquin, Duraquin, Quinidex, and other brands).

Persons who take these drugs should see their physician regularly. The physician will check to make sure the medicine is working as it should and will note any unwanted side effects.

Some people feel dizzy, lightheaded, or faint when using these drugs. This medicine may cause blurred vision or other vision problems. Because of these possible problems, anyone who takes these drugs should not drive, use machinesor do anything else that might be dangerous until they have found out how thedrugs affect them. Anyone taking this medicine should not drink alcohol without his or her physician's approval.

Some antiarrhythmic drugs may change the results of certain medical tests. Before having medical tests, anyone taking this medicine should alert the health care professional in charge. Anyone who is taking antiarrhythmic drugs should be sure to tell the health care professional in charge before having any surgical or dental procedures or receiving emergency treatment.

Antiarrhythmic drugs may cause dry mouth. Mouth dryness that continues over along time may contribute to tooth decay and other dental problems.

People taking antiarrhythmic drugs may sweat less, which can cause the body temperature to rise. Anyone who takes this medicine should be careful not to become overheated during exercise or hot weather and should avoid hot baths, hot tubs, and saunas.

People with certain medical conditions may have problems if they take antiarrhythmic drugs. For example, antiarrhythmic drugs may cause low blood sugar, which can be a particular problem for people with congestive heart disease ordiabetes. Before prescribing these drugs, the physician should be warned of any existing medical conditions.

Antiarrhythmic drugs may interact with other medicines. When this happens, the effects of one or both of the drugs may change or the risk of side effectsmay be greater. Anyone who takes antiarrhythmic drugs should let the physician know all other medicines he or she is taking.

Anyone who has had unusual reactions to an antiarrhythmic drug in the past should let his or her physician know before taking this type of medicine again.Patients taking procainamide should let their physicians know if they have ever had an unusual or allergic reaction to procaine or any other "caine-type"medicine, such as xylocaine or lidocaine. Patients taking quinidine should mention any previous reactions to quinine. The physician should also be told about any allergies to foods, dyes, preservatives, or other substances.

The effects of taking antiarrhythmic drugs in pregnancy have not been studiedin humans. In studies of laboratory animals, this medicine increased the risk of miscarriage. Antiarrhythmic drugs pass into breast milk. Women who are pregnant or breastfeeding should check with their physicians before taking this medicine.

Serious side effects are not common, but may occur. Anyone who has unusual symptoms after taking antiarrhythmic drugs should get in touch with his or herphysician.

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