quinidine, Quinidine Gluconate, Quinidine Sulfate (cont.)

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Medical and Pharmacy Editor:

Quinidine blocks the normal effect of the vagus nerve on the heart, causing an increase in the rate at which the heart beats. Quinidine reduces the force of contraction of heart muscle cells, and therefore may impair the pumping efficiency of failing heart muscle as in congestive heart failure. Quinidine blocks alpha-receptors on the muscle cells that surround arteries which relaxes the muscle cells, lowers blood pressure ,and can cause excessively low blood pressure when combined with other drugs that also relax these muscle cells. Quinidine was approved by the FDA in July 1950.

PRESCRIPTION: Yes

GENERIC AVAILABLE: Yes

PREPARATIONS: Tablets: 200, 300, and 324 mg. Injections: 800 mg.

STORAGE: Quinidine should be stored at room temperature, 20-25 C (68-77 F). It should be dispensed in well-closed, light-resistant container.

PRESCRIBED FOR: Quinidine is an antiarrhythmic drug used in the treatment of abnormal heart rhythms, such as: atrial fibrillation, atrial flutter, and ventricular arrhythmias such as paroxysmal ventricular tachycardia. Quinidine also is used to treat malaria.

DOSING:

  • 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.

DRUG INTERACTIONS: 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.



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