Description
Quinidine 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.
This product is available in the following dosage forms:
- Tablet
- Tablet, Extended Release
Before Using
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 this medicine, the following should be considered:
Allergies
Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.
Pediatric
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.
Geriatric
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.
Breastfeeding
Studies in women suggest that this medication poses minimal risk to the infant when used during breastfeeding.
Drug Interactions
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 this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.
Using this medicine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.
- Atazanavir
- Aurothioglucose
- Bepridil
- Cisapride
- Colchicine
- Dronedarone
- Fingolimod
- Fluconazole
- Grepafloxacin
- Itraconazole
- Ketoconazole
- Lefamulin
- Levoketoconazole
- Levomethadyl
- Mesoridazine
- Mifepristone
- Nelfinavir
- Nirmatrelvir
- Pimozide
- Piperaquine
- Posaconazole
- Ritonavir
- Saquinavir
- Sparfloxacin
- Terfenadine
- Thioridazine
- Tipranavir
- Vernakalant
- Voriconazole
- Ziprasidone
Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
- Abametapir
- Acetazolamide
- Adagrasib
- Afatinib
- Ajmaline
- Alefacept
- Alfuzosin
- Amiodarone
- Amisulpride
- Amitriptyline
- Amoxapine
- Amphetamine
- Amprenavir
- Anagrelide
- Apomorphine
- Aprindine
- Arbutamine
- Aripiprazole
- Aripiprazole Lauroxil
- Arsenic Trioxide
- Artemether
- Asciminib
- Asenapine
- Astemizole
- Atracurium
- Avacopan
- Azithromycin
- Bedaquiline
- Benzphetamine
- Berotralstat
- Betrixaban
- Boceprevir
- Brexpiprazole
- Buprenorphine
- Buserelin
- Carbamazepine
- Ceritinib
- Chloral Hydrate
- Chloroquine
- Ciprofloxacin
Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
- Abarelix
- Amiloride
- Atenolol
- Cimetidine
- Dalfopristin
- Dextromethorphan
- Dicumarol
- Fosphenytoin
- Galantamine
- Magaldrate
- Magnesium Carbonate
- Magnesium Hydroxide
- Magnesium Oxide
- Magnesium Trisilicate
- Metoprolol
- Nisoldipine
- Phenytoin
- Propranolol
- Quinupristin
- Rifapentine
- Tolterodine
- Verapamil
Other Interactions
Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.
Using this medicine with any of the following may cause an increased risk of certain side effects but may be unavoidable in some cases. If used together, your doctor may change the dose or how often you use this medicine, or give you special instructions about the use of food, alcohol, or tobacco.
- Grapefruit Juice
Other Medical Problems
The presence of other medical problems may affect the use of this medicine. 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
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 this medicine 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 this medicine. If your dose is different, do not change it unless your doctor tells you to do so.
The amount of medicine 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 using the medicine.
- 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 abnormal heart rhythm:
- 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 abnormal heart rhythm:
- 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.
- For abnormal heart rhythm:
Missed Dose
If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.
Storage
Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.
Keep out of the reach of children.
Do not keep outdated medicine or medicine no longer needed.
Precautions
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
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
Some 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. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
More common
- Diarrhea
- loss of appetite
- muscle weakness
- nausea or vomiting
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
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