In many trials of antiarrhythmic therapy for non-life-threatening arrhythmias, active antiarrhythmic therapy has resulted in increased mortality; the risk of active therapy is probably greatest in patients with structural heart disease.
In the case of quinidine used to prevent or defer recurrence of atrial flutter/fibrillation, the best available data come from a meta-analysis described under CLINICAL PHARMACOLOGY/Clinical Effects above. In the patients studied in the trials there analyzed, the mortality associated with the use of quinidine was more than three times as great as the mortality associated with the use of placebo.
Another meta-analysis, also described under CLINICAL PHARMACOLOGY/Clinical Effects, showed that in patients with various non-life-threatening ventricular arrhythmias, the mortality associated with the use of quinidine was consistently greater than that associated with the use of any of a variety of alternative antiarrhythmics.
Quinidine is an antimalarial schizonticide and an antiarrhythmic agent with Class Ia activity; it is the d-isomer of quinine, and its molecular weight is 324.
Conversion of atrial fibrillation/flutter
In patients with symptomatic atrial fibrillation/flutter whose symptoms are not adequately controlled by measures that reduce the rate of ventricular response, quinidine gluconate is indicated as a means of restoring normal sinus rhythm. If this use of quinidine gluconate does not restore sinus rhythm within a reasonable time (see
DOSAGE AND ADMINISTRATION), then quinidine gluconate should be discontinued.
Reduction of frequency of relapse into atrial fibrillation/flutter
Chronic therapy with quinidine gluconate is indicated for some patients at high risk of symptomatic atrial fibrillation/flutter, generally patients who have had previous episodes of atrial fibrillation/flutter that were so frequent and poorly tolerated as to outweigh, in the judgment of the physician and the patient, the risks of prophylactic therapy with quinidine gluconate. The increased risk of death should specifically be considered. Quinidine gluconate should be used only after alternative measures (e.g., use of other drugs to control the ventricular rate) have been found to be inadequate.
In patients with histories of frequent symptomatic episodes of atrial fibrillation/flutter, the goal of therapy should be an increase in the average time between episodes. In most patients, the tachyarrhythmia will recur during therapy, and a single recurrence should not be interpreted as therapeutic failure.
Suppression of ventricular arrhythmias
Quinidine gluconate is also indicated for the suppression of recurrent documented ventricular arrhythmias, such as sustained ventricular tachycardia, that in the judgment of the physician are life-threatening. Because of the proarrhythmic effects of quinidine, its use with ventricular arrhythmias of lesser severity is generally not recommended, and treatment of patients with asymptomatic ventricular premature contractions should be avoided. Where possible, therapy should be guided by the results of programmed electrical stimulation and/or Holter monitoring with exercise.
Antiarrhythmic drugs (including quinidine gluconate) have not been shown to enhance survival in patients with ventricular arrhythmias.
Media Articles Related to Quinidine
Malaria Patients Out of ICU in 4 Days With IV Artesunate
Source: Medscape Critical Care Headlines [2015.08.25]
Intravenous artesunate was a safe and clinically beneficial alternative to quinidine for patients with severe or complicated malaria.
Medscape Medical News
Published Studies Related to Quinidine
Nonlinear pharmacokinetics of oral quinidine and verapamil in healthy subjects: a clinical microdosing study. [2011.08]
Microdosing studies are effective in enabling the early identification of the pharmacokinetic properties of compounds administered to humans. However, the nonlinearity of the pharmacokinetics between microdose and therapeutic dose, attributable to the saturation of metabolic enzymes and transporters, is a major concern.
Dextromethorphan/quinidine: in pseudobulbar affect. [2011.05.01]
Pseudobulbar affect is characterized by uncontrollable, inappropriate laughing and/or crying that is either unrelated or out of proportion to the emotions felt by the patient and occurs in patients with neurological disorders, such as amyotrophic lateral sclerosis (ALS), multiple sclerosis or traumatic brain injury...
Dextromethorphan plus ultra low-dose quinidine reduces pseudobulbar affect. [2010.11]
OBJECTIVE: To evaluate dextromethorphan combined with ultra low-dose quinidine (DMq) for treating pseudobulbar affect (PBA) in patients with amyotrophic lateral sclerosis (ALS) or multiple sclerosis (MS)... INTERPRETATION: DMq markedly reduced PBA frequency and severity, decreasing the condition's detrimental impact on a patient's life, with satisfactory safety and high tolerability. The findings expand the clinical evidence that DMq may be an important treatment for patients suffering from the socially debilitating symptoms of PBA.
Efficacy and tolerability of oral propafenone versus quinidine in the treatment of recent onset atrial fibrillation: A randomized, prospective study. 
BACKGROUND: A prospective, randomized study was conducted to evaluate the efficacy and tolerability of oral propafenone and quinidine for the conversion of paroxysmal atrial fibrillation (AF)... CONCLUSIONS: Although both drugs revealed the same effectiveness, the conversion to sinus rhythm in the group treated with propafenone was observed more quickly despite the longer paroxysmal AF episode duration.
Effects of ketoconazole and quinidine on pharmacokinetics of pactimibe and its plasma metabolite, R-125528, in humans. [2008.08]
Pactimibe sulfate is a novel acyl coenzyme A:cholesterol acyltransferase inhibitor developed for the treatment of hypercholesterolemia and atherosclerotic diseases. Pactimibe has two equally dominant clearance pathways forming R-125528 by CYP3A4 and M-1 by CYP2D6 in vitro... These values were well in accordance with the values observed in this study.
Clinical Trials Related to Quinidine
A Study to Evaluate the Effect of Genotype on LY2216684 [Recruiting]
The study will evaluate how genetic profiles respond to LY2216684 and the effect of
Quinidine on the pharmacokinetics (PK) of LY2216684 in a specific genetic profile. Side
effects will be documented.
Efficacy, Safety and Tolerability Study of AVP-923 (Dextromethorphan/Quinidine) for Treatment of Symptoms of Agitation in Alzheimer's Patients [Recruiting]
The objectives of the study are to evaluate the safety, tolerability and efficacy of AVP-923
compared to placebo, for the treatment of symptoms of agitation in patients with Alzheimer's
Safety and Efficacy of Dextromethorphan and Quinidine in the Treatment of the Pain of Diabetic Neuropathy [Completed]
The purpose of this study is to determine whether dextromethorphan (Neurodex) and quinidine
are effective in the treatment of pain of diabetic neuropathy.
Empiric Quinidine for Asymptomatic Brugada Syndrome [Recruiting]
The purpose of this study is to determine if quinidine therapy (not guided by the results of
electrophysiologic studies) will reduce the long-term risk of arrhythmic events in
asymptomatic Brugada Syndrome.
Effect of P-glycoprotein Inhibition on Lenalidomide Pharmacokinetics in Healthy Males [Recruiting]
To find out if the blood level of lenalidomide can be changed when a drug that prevents
p-glycoprotein (a protein naturally present in the body that helps carry substances across
cell membranes that is found in many parts of the body like the intestines, liver, and
kidneys) from working (called a P-gp inhibitor) when taken together with lenalidomide. The
study is also trying to find out if blood level of temsirolimus can be changed when a
subject takes lenalidomide together with temsirolimus.
Page last updated: 2015-08-25