Brand name:

Quinidex Extentabs

Pronounced: KWIN-i-deks Eks-TEN-tabs
Generic name: Quinidine sulfate

Why is this drug prescribed?

Quinidex Extentabs are used to correct certain types of irregular heart rhythms and to slow an abnormally fast heartbeat.

Most important fact about this drug

It is important to take only the prescribed amount of this medication--no more and no less. Try to keep your doses at regularly spaced intervals, and be sure not to miss any.

How should you take this medication?

Take Quinidex exactly as prescribed.

--If you miss a dose...

Take it as soon as you remember, if it is within 2 hours of your scheduled time. 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 in a tightly closed container, away from light.

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 Quinidex Extentabs.

• More common side effects include:
  Abdominal pain, diarrhea, hepatitis, inflammation of the esophagus (gullet), loss of appetite, nausea, vomiting

• Less common or rare side effects may include:
  Allergic reaction (symptoms include: swelling of face, lips, tongue, throat, arms, and legs, sore throat, fever and chills, difficulty swallowing, chest pain), anemia, apprehension, asthma attack, blind spots, blood clots, blurred vision, changes in skin pigmentation, confusion, delirium, depression, dilated pupils, disturbed color perception, double vision, eczema, excitement, fainting, fever, fluid retention, flushing, headache, hearing changes, hepatitis, hives, inability to breathe, intense itching, intolerance to light, irregular heartbeats, joint pain, lack of coordination, low blood pressure, lupus erythematosus (inflammation of connective tissue), mental decline, muscle pain, night blindness, psoriasis, rash, reddish or purplish spots below the skin, skin eruptions and scaling, skin sensitivity to light, vertigo, vision changes, wheezing

Another possible side effect is a sensitivity reaction called cinchonism. Symptoms include blurred or double vision, confusion, delirium, diarrhea, headache, intolerance to light, loss of hearing, ringing in the ears, vertigo, and vomiting.

Why should this drug not be prescribed?

Do not take this medication if you have ever had an allergic reaction to quinidine. Also avoid this medication if quinine or quinidine causes you to bruise easily.

Quinidex is prescribed only for certain specific types of heart irregularity, and should be avoided when other irregularities are present. It could also prove harmful if you have myasthenia gravis (abnormal muscle weakness) or a similar condition.

Special warnings about this medication

Quinidex is reserved for certain kinds of dangerously rapid heart irregularities. It works well for some people, providing them with significant symptomatic relief. However, you should know that--on average for all cases--it has not been shown to improve chances of long-term survival, and could actually lower the odds.

Remember, too, that under certain conditions (slow heart rate, low potassium or magnesium levels) Quinidex can cause certain types of heart irregularity. It can also cause the condition known as heart block, and should be used with caution if you have partial heart block.

Also use Quinidex Extentabs cautiously if you have kidney or liver disease. Your doctor will check your blood count and liver and kidney function periodically during long-term therapy.

There have been rare cases of severe allergic reaction to quinidine, especially during the first few weeks of therapy. Discuss any allergic reactions you have experienced with your doctor.

Do not confuse Quinidex with quinine, which, although related, is used to treat malaria.

Possible food and drug interactions
when taking this medication

Concentrations of digoxin (Lanoxin) in your blood may increase or even double when this drug is taken with Quinidex Extentabs. Your doctor may need to reduce the amount of digoxin you take.

A decrease in your salt intake can lead to a higher blood level of Quinidex. Try to keep the salt in your diet constant. Grapefruit juice may also have an impact on Quinidex levels. It's best to avoid it.

If Quinidex Extentabs are 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 Quinidex Extentabs with the following:

Amiodarone (Cordarone)
Antacids containing magnesium, such as Maalox and Mylanta
Antispasmodic drugs such as Bentyl
Aspirin
Beta-blocking blood pressure medications such as Inderal and Tenormin
Blood thinners such as Coumadin
Certain antidepressants such as Elavil and Tofranil
Certain diuretic drugs such as Diamox and Daranide
Cimetidine (Tagamet)
Codeine
Decamethonium
Digitoxin (Crystodigin)
Diltiazem (Cardizem)
Disopyramide (Norpace)
Felodipine (Plendil)
Haloperidol (Haldol)
Hydrocodone (Vicodin)
Ketoconazole (Nizoral)
Major tranquilizers such as Stelazine and Thorazine
Mexiletine (Mexitil)
Nicardipine (Cardene)
Nifedipine (Procardia)
Nimodipine (Nimotop)
Phenobarbital
Phenytoin (Dilantin)
Physostigmine (Antilirium)
Procainamide (Procanbid)
Reserpine (Diupres)
Rifampin (Rifadin)
Sodium bicarbonate
Sucralfate (Carafate)
Thiazide diuretics such as Dyazide and HydroDIURIL
Verapamil (Calan)

Special information
if you are pregnant or breastfeeding

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

Recommended dosage

ADULTS

The usual dosage is 1 Quinidex Extentab every 8 to 12 hours.

Overdosage

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

• The symptoms of Quinidex Extentabs overdose may include:
  Abnormal heart rhythms, blurred or double vision, confusion, delirium, diarrhea, headache, intolerance to light, loss of hearing, low blood pressure, ringing in the ears, vertigo, vomiting