Quinidine (Systemic)

Brand name(s): Cardioquin

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

Last Revised: 5/26/1999