Quinidine

Synonyms: Quinidine Sulfate, Quinidine Gluconate.

Brand Names: Apo-Quinidine, Biquin Durules, Cardioquin, Chinidin, Cin-Quin, Coccinine, Conchinin, Conchinine, Conquinine, Duraquin, Kinidin, Novoquinidin, Pitayin, Pitayine, Quin-Release, Quinact, Quinaglute, Quinaglute Dura-Tabs, Quinalan, Quinate, Quinatime, Quindine, Quinicardine, Quinidex, Quinidex Extentabs, Quinora.

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Dosing and Administration

Because the kinetics of absorption may vary with the patient's peripheral perfusion, intramuscular injection of Quinidine gluconate is not recommended.

Treatment of P. falciparum malaria — Two regimens have each been shown to be effective, with or without concomitant exchange transfusion. There are no data indicating that either should be preferred to the other.

In Regimen A, each patient received a loading dose of 15 mg/kg of Quinidine base (that is, 24 mg/kg of Quinidine gluconate) in 250 mL of normal saline infused over 4 hours. Thereafter, each patient received a maintenance regimen of 7.5 mg/kg of base (12 mg/kg of Quinidine gluconate) infused over 4 hours every 8 hours, starting 8 hours after the beginning of the loading dose. This regimen was continued for 7 days, except that in patients able to swallow, the maintenance infusions were discontinued, and approximately the same daily doses of Quinidine were supplied orally, using 300–mg tablets of Quinidine sulfate.
In Regimen B, each patient received a loading dose of 6.25 mg/kg of Quinidine base (that is, 10 mg/kg of Quinidine gluconate) in approximately 5 mL/kg of normal saline over 1–2 hours. Thereafter,each patient received a maintenance infusion of 12.5 μg/kg/min of base (that is, 20 μg/kg/min of Quinidine gluconate). In patients able to swallow, the maintenance infusion was discontinued, and eight–hourly oral quinine sulfate was administered to provide approximately as much daily quinine base as the patient had been receiving Quinidine base (for example, each adult patient received 650 mg of quinine sulfate every eight hours). Quinidine/quinine therapy was continued for 72 hours or until parasitemia had decreased to 1% or less, whichever came first. After completion of Quinidine/quinine therapy, adults able to swallow received a single 1500–mg/75–mg dose of sulfadoxine/pyrimethamine (FANSIDAR®, Roche Laboratories) or a seven–day course of tetracycline (250 mg four times daily), while those unable to swallow received seven–day courses of intravenous doxycycline hyclate (VIBRAMYCIN®, Roerig), 100 mg twice daily. Most of the patients described as having been treated with this regimen also underwent exchange transfusion. Small children have received this regimen without dose adjustment and with apparent good results, notwithstanding the known differences in Quinidine pharmacokinetics between pediatric patients and adults.

Even in patients without preexisting cardiac disease, antimalarial use of Quinidine has occasionally been associated with hypotension, QTc prolongation, and cinchonism.

Treatment of symptomatic atrial fibrillation/flutter — A patient receiving an intravenous infusion of Quinidine must be carefully monitored, with frequent or continuous electrocardiography and blood–pressure measurement. The infusion should be discontinued as soon as sinus rhythm is restored: the QRS complex widens to 130% of its pre–treatment duration; the QTc interval widens to 130% of its pre–treatment duration, and is then longer than 500 ms; P waves disappear; or the patient develops significant tachycardia, symptomatic bradycardia, or hypotension.
To prepare Quinidine for infusion, the contents of the supplied vial (80 mg/mL) should be diluted to 50 mL (16 mg/mL) with 5% dextrose. The resulting solution may be stored for up to 24 hours at room temperature or up to 48 hours at 4°C (40°F).
Because Quinidine may be absorbed to PVC tubing, tubing length should be minimized. In one study (Am J Health Syst Pharm. 1996; 53:655–8), use of 112 inches of tubing resulted in 30% loss of Quinidine, but drug loss was less than 3% when only 12 inches of tubing was used.
An infusion of Quinidine must be delivered slowly, preferable under control of a volumetric pump, no faster than 0.25 mg/kg/min (that is, no faster than 1 mL/kg/hour). During the first few minutes of the infusion, the patient should be monitored especially closely for possible hypersensitive or idiosyncratic reactions.
Most arrhythmias that will respond to intravenous Quinidine will respond to a total dose of less than 5 mg/kg, but some patients may require as much as 10 mg/kg. If conversion to sinus rhythm has not been achieved after infusion of 10 mg/kg, then the infusion should be discontinued, and other means of conversion (eg, direct–currentcardioversion) should be considered.

Treatment of life–threatening ventricular arrhythmias — Dosing regimens for the use of intravenous Quinidine gluconate in controlling life–threatening ventricular arrhythmias have not been adequately studied. Described regimens have generally been similar to the regimen described just above for the treatment of symptomatic atrial fibrillation/flutter.

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