Brand Names

Category

• Antiarrhythmic
• antimalarial

Description

Quinidine (KWIN-i-deen) is used to treat abnormal heart rhythms. It is also used to treat malaria.

Do not confuse this medicine with quinine , which, although related, has different medical uses.

Quinidine is available only with your doctor's prescription, in the following dosage forms:

Oral
• Tablets (U.S. and Canada)
• Extended-release tablets (U.S. and Canada)

Parenteral
• Injection (U.S. and Canada)

Before Using This Medicine

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For quinidine, the following should be considered:

Allergies--Tell your doctor if you have ever had any unusual or allergic reaction to quinidine or quinine. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy--Studies on effects in pregnancy have not been done in either humans or animals. However, quinidine has been used during pregnancy and, although serious side effects are uncommon, it has been shown to cause mild uterine contractions, premature labor, and blood problems in the neonate.

Breast-feeding--Quinidine passes into breast milk and, because of the potential for problems in the nursing infant, it is generally not recommended in mothers who are breast-feeding.

Children--Quinidine has not been widely studied in children; however, it is used in children to treat abnormal heart rhythms and to treat malaria. Children may be able to take higher doses than adults and may have fewer side effects (such as vomiting, loss of appetite, and diarrhea) than adults.

Older adults--Many medicines have not been studied specifically in older people. Therefore, it may not be known whether they work exactly the same way they do in younger adults. Although there is no specific information comparing use of quinidine in the elderly with use in other age groups, this medicine is not expected to cause different side effects or problems in older people than it does in younger adults. However, quinidine may remain in the bodies of older adults longer than it does in younger adults, which may increase the risk of side effects and which may require lower doses.

Other medicines--Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking quinidine, it is especially important that your health care professional know if you are taking any of the following:

• Amiodarone--Effects may be increased because levels of quinidine in the body may be increased

• Digitalis medicines (heart medicine)--Effects may be increased because levels of digitalis in the body may be increased

• Antidepressants, tricyclic, such as amitriptyline (e.g., Elavil), clomipramine (e.g., Anafranil), desipramine (e.g., Norpramin), doxepin (e.g., Sinequan), imipramine (e.g., Tofranil), and nortriptyline (e.g., Pamelor) or
• Astemizole (e.g., Hismanal) or
• Chloroquine (e.g., Aralen) or
• Clarithromycin (e.g., Biaxin) or
• Cisapride (e.g., Propulsid) or
• Diphenhydramine (e.g., Benadryl) or
• Erythromycin (e.g., Erythrocin, Erytab) or
• Fludrocortisone (e.g., Florinef) or
• Halofantrine (e.g., Halfan) or
• Haloperidol (e.g., Haldol) or
• Indapamide (e.g., Lozol) or
• Maprotiline (e.g., Ludiomil) or
• Mefloquine (e.g., Lariam) or
• Other heart medicine, including bepridil (e.g., Vascor), beta-adrenergic blocking agents such as propranolol (e.g., Inderal), diltiazem (e.g., Cardizem), disopyramide (e.g. Norpace), encainide (e.g., Encaid), flecainide (e.g., Tambocor), ibutilide (e.g., Corvert), lidocaine (e.g., Xylocaine), procainamide (e.g., Procanbid), propafenone (e.g., Rythmol), sotalol (e.g., Betapace, Sotacor), tocainide (e.g., Tonocard), and verapamil (e.g., Calan, Isoptin) or
• Pentamidine (e.g., NebuPent, Pentam) or
• Phenothiazines (e.g., chlorpromazine [e.g., Thorazine], perphenazine [e.g., Trilafon], prochlorperazine [e.g., Compazine], thioridazine [e.g., Mellaril]) or
• Pimozide (e.g., Orap) or
• Risperidone (e.g., Risperdal) or
• Sparfloxacin (e.g., Zagam) or
• Tamoxifen (e.g., Nolvadex) or
• Thiothixene (e.g., Navane) or
• Trimethoprim and sulfamethoxazole combination (e.g., Bactrim, Septra)--Effects on the heart may be increased

• Urinary alkalizers (medicine that makes the urine less acid, such as acetazolamide [e.g., Diamox], dichlorphenamide [e.g., Daranide], methazolamide [e.g., Neptazane], and sodium bicarbonate [baking soda])--Effects may be increased because levels of quinidine in the body may be increased

Other medical problems--The presence of other medical problems may affect the use of quinidine. Make sure you tell your doctor if you have any other medical problems, especially:

• Electrolyte disorders--Quinidine may worsen heart rhythm problems

• Heart disease or
• Myasthenia gravis--Quinidine may make these conditions worse

• Kidney disease or
• Liver disease--Effects may be increased because of slower removal of quinidine from the body

Proper Use of This Medicine

Take this medicine exactly as directed . Do not take more of this medicine and do not take it more often than your doctor ordered. Do not miss any doses.

Taking quinidine with food may help lessen stomach upset.

For patients taking the extended-release tablet form of this medicine:

• Quinidex Extentabs or Biquin Durules--Swallow the tablets whole; do not break, crush, or chew before swallowing. Note that Biquin Durules may sometimes appear as a whole tablet in the stool; this tablet is just the empty shell that is left after the medicine has been absorbed into the body.
• Quinaglute Duratabs or Quin-Release--These tablets may be broken in half; however, they should not be crushed or chewed before swallowing.

Dosing--The dose of quinidine will be different for different patients. Follow your doctor's orders or the directions on the label . The following information includes only the average doses of quinidine. If your dose is different, do not change it unless your doctor tells you to do so.

The number of tablets that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are taking quinidine .

• For regular (short-acting) oral dosage form (tablets):
  • For abnormal heart rhythm:
    • Adults--200 to 650 milligrams (mg) three or four times a day.
    • Children--30 to 40 mg per kilogram (kg) (13.6 to 18.2 mg per pound) of body weight per day. Your doctor may increase the dose if needed.
• For long-acting oral dosage form (tablets):
  • For abnormal heart rhythm:
    • Adults--300 to 660 mg every eight to twelve hours.
    • Children--30 to 40 mg per kilogram (kg) (13.6 to 18.2 mg per pound) of body weight per day. Your doctor may increase the dose if needed.
• For injection dosage form:
  • For abnormal heart rhythm:
    • Adults--190 to 380 mg injected into the muscle every two to four hours. Or, up to 0.25 mg per kg (0.11 mg per pound) of body weight per minute in a solution injected into a vein.
    • Children--Dose must be determined by your doctor.
  • For malaria:
    • Adults--10 mg per kg (4.54 mg per pound) of body weight in a solution injected slowly into a vein over one to two hours. Then, 0.02 mg per kg (0.009 mg per pound) of body weight per minute is given. Or, 24 mg per kg (10.91 mg per pound) of body weight in a solution injected slowly into a vein over a four-hour period. Then, eight hours after the first dose, 12 mg per kg (5.45 mg per pound) of body weight, injected slowly into a vein over a four-hour period, and repeated every eight hours.
    • Children--Dose must be determined by your doctor.

Missed dose--If you miss a dose of this medicine and remember within 2 hours of the missed dose, take it as soon as possible. However, if you do not remember until later, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Storage--To store this medicine:

• Keep out of the reach of children.
• Store away from heat and direct light.
• Do not store in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down.
• Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.

Precautions While Using This Medicine

It is very important that your doctor check your progress at regular visits to make sure that the quinidine is working properly and does not cause unwanted effects.

Do not stop taking this medicine without first checking with your doctor, to avoid possible worsening of your condition.

Before having any kind of surgery (including dental surgery) or emergency treatment, tell the medical doctor or dentist in charge that you are taking this medicine.

Dizziness or lightheadedness may occur with this medicine, especially when you get up from a lying or sitting position. Getting up slowly may help.

Fainting may occur with this medicine . Do not drive or do anything else that could be dangerous if fainting occurs .

. Check with your doctor immediately if you faint or experience other side effects with this medicine .

Your doctor may want you to carry a medical identification card or bracelet stating that you are using this medicine.

Side Effects of This Medicine

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

Less common

Abdominal pain and/or yellow eyes or skin; blurred and/or double vision, confusion, delirium, disturbed color perception, headache, noises or ringing in the ear, and/or visual intolerance of light; dizziness or lightheadedness; fainting; fever

Rare

Chest pain, fever, general discomfort, joint pain, joint swelling, muscle pain, and/or skin rash; nosebleeds or bleeding gums; unusual tiredness or weakness and/or pale skin

Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if any of the following side effects continue or are bothersome:

More common

Diarrhea; loss of appetite; muscle weakness; nausea or vomiting

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.

Revised: 5/26/99

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