What is quinidine?

Quinidine is an antiarrhythmic agent and antimalarial drug.

Is quinidine available as a generic drug?


Do I need a prescription for quinidine?


What are the uses for quinidine?

What are the side effects of quinidine?

The most common side effects are:

Other important side effects include:

  • Irregular heartbeat
  • Chest pain
  • Skin rash
  • Hearing changes (ringing or loss of hearing)
  • Vision changes (blurred or light sensitivity)
  • Unusual bleeding

If patients experience any of the above side effects, they should call their doctor immediately.


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What is the dosage for quinidine?

  • For adults, the dosage range for quinidine gluconate is from 648 to 2592 mg/day.
  • For adults, the dosage range for quinidine sulfate is from 400 to 4000 mg/day.
  • For adults, the dosage range for quinidine gluconate injection is 400 to 2400 mg/day.

Which drugs or supplements interact with quinidine?

  • Azole antifungals such as ketoconazole (Nizoral), fluconazole (Diflucan), itraconazole (Sporanox PulsePak), voriconazole (VFEND), posaconazole (Noxafil), and protease inhibitor/antiretroviral drugs such as indinavir (Crixivan), and saquinavir (Invirase) should not be used with quinidine since their concomitant use can increase quinidine levels by inhibiting removal of quinidine by the liver. Increased quinidine levels can increase the risk of quinidine toxicity and cardiac arrhythmias.
  • Phenothiazines such as thioridazine (Mellaril), an antipsychotic drug, and tricyclic antidepressants such as amitriptyline (Elavil, Endep) should not be used with quinidine since they can cause cardiac arrhythmias, and their use with quinidine increases the risk of cardiac arrhythmias.
  • Quinidine increases the action of the blood thinner warfarin (Coumadin, Jantoven), due to synergistic effects and can lead to excessive blood thinning and bleeding. A decrease in warfarin dose usually is required. Blood levels of digoxin (Lanoxin) are raised by quinidine due to a reduction in removal or reduced distribution in the body of digoxin. This can give rise to intoxication with digoxin, and it is important to reduce the dose of digoxin to prevent toxicity.
  • Removal of quinidine by the liver is accelerated by phenobarbital, phenytoin (Dilantin), and rifampin (Rifamate), requiring an increase in quinidine dose.
  • With the exact mechanism not known, amiodarone (Cordarone), another type of antiarrhythmic drug, may decrease removal of quinidine by the kidneys or liver giving rise to elevated quinidine blood levels, which may result in life-threatening arrhythmias, including torsades de pointes. It is important, therefore, to decrease quinidine doses when it is given concomitantly with amiodarone.
  • Cimetidine (Tagamet) increases quinidine levels by decreasing the elimination of quinidine giving rise to elevated quinidine serum levels that may lead to quinidine toxicity.

Is quinidine safe to take if I'm pregnant or breastfeeding?

  • Safety and efficacy of quinidine has not been established in pregnant women.
  • Quinidine can enter breast milk and should be avoided by nursing mothers.

What else should I know about quinidine?

What preparations of quinidine are available?
  • Tablets: 200, 300, and 324 mg.
  • Injections: 800 mg.
How should I keep quinidine stored?
  • Quinidine should be stored at room temperature, 20 C - 25 C (68 F - 77 F).
  • It should be dispensed in well-closed, light-resistant container.


Quinidine (Discontinued Brands: Cardioquine, Cin-Quin, Duraquin, Quinidex, Quinora, Quinact, Quinatime, Quinaglute, Quinalan) is an antiarrhythmic medication prescribed for abnormal heart rhythms such as atrial fibrillation, atrial flutter, and ventricular arrhythmias such as paroxysmal ventricular tachycardia. Quinidine also is prescribed to treat malaria. Review side effects, drug interactions, warnings and precautions, and pregnancy and breastfeeding safety information prior to taking this medication.

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