Quinidine — uses, dosing, side effects & the brands that sell it · pharmaranks
Quinidine: uses, dosing, side effects & brands
Quinidine is an antiarrhythmic sold in the U.S. under 4 brand and generic names, for atrial fibrillation and atrial flutter. Below: what the FDA label says, every product that contains it, what the pills look like, and its recall record.
By the pharmaranks editorial team·Reviewed against the FDA (openFDA label, NDC Directory & Enforcement) sources·How we research
Key facts
Drug class
Antiarrhythmic
Treats
Atrial Fibrillation and Atrial Flutter
Available as
Tablet · Tablet, extended release
Sold as
4 products — Quinact, Quinidex and Quinidine Sulfate, and others
From the FDA label for Quinact (application ANDA085978). Other quinidine products — different forms, different strengths — are dosed differently. Follow the label for the one you were prescribed.
The dose of quinidine delivered by quinidine gluconate extended-release tablets may be titrated by breaking a tablet in half. If tablets are crushed or chewed, their extended-release properties will be lost. The dosage of quinidine varies considerably depending upon the general condition and the cardiovascular state of the patient. Conversion of atrial fibrillation/flutter to sinus rhythm Especially in patients with known structural heart disease or other risk factors for toxicity, initiation or dose-adjustment of treatment with quinidine gluconate should generally be performed in a setting where facilities and personnel for monitoring and resuscitation are continuously available. Patients with symptomatic atrial fibrillation/flutter should be treated with quinidine gluconate only after ventricular rate control (e.g., with digitalis or β-blockers) has failed to provide satisfactory control of symptoms. Adequate trials have not identified an optimal regimen of quinidine gluconate for conversion of atrial fibrillation/flutter to sinus rhythm. In one reported regimen, the patient first receives two tablets (648 mg; 403 mg of quinidine base) of quinidine gluconate every eight hours. If this regimen has not resulted in conversion after 3 or 4 doses, then the dose is cautiously increased. If, at any point during administration, the QRS complex widens to 130% of its pre-treatment…
Quinidine side effects
Quinidine preparations have been used for many years, but there are only sparse data from which to estimate the incidence of various adverse reactions. The adverse reactions most frequently reported have consistently been gastrointestinal, including diarrhea, nausea, vomiting, and heartburn/esophagitis. In the reported study that was closest in character to the predominant approved use of quinidine gluconate, 86 adult outpatients with atrial fibrillation were followed for six months while they received slow-release quinidine bisulfate tablets, 600 mg (approximately 400 mg of quinidine base) twice daily. The incidences of adverse experiences reported more than once were as shown in the table below. The most serious quinidine-associated adverse reactions are described above under WARNINGS . ADVERSE EXPERIENCES REPORTED MORE THAN ONCE IN 86 PATIENTS WITH ATRIAL FIBRILLATION Incidence (%) diarrhea 21 (24%) fever 5 (6%) rash 5 (6%) arrhythmia 3 (3%) abnormal electrocardiogram 3 (3%) nausea/vomiting 3 (3%) dizziness 3 (3%) headache 3 (3%) asthenia 2 (2%) cerebral ischemia 2 (2%) Vomiting and diarrhea can occur as isolated reactions to therapeutic levels of quinidine, but they may also be the first signs of cinchonism , a syndrome that may also include tinnitus, reversible high-frequency hearing loss, deafness, vertigo, blurred vision, diplopia, photophobia, headache, confusion, and…
Every quinidine product we track (4)
Same active ingredient — different manufacturer, form, price and FDA recall record. That last one is what our independent score measures.
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 324.43. Quinidine gluconate is the gluconate salt of quinidine; its chemical name is cinchonan-9-ol, 6'-methoxy-, (9S)-, mono-D-gluconate; its structural formula is: Its empirical formula is C 20 H 24 N 2 O 2 • C 6 H 12 O 7 , and its molecular weight is 520.58, of which 62.3% is quinidine base. Each quinidine gluconate extended-release tablet contains 324 mg of quinidine gluconate (202 mg of quinidine base) in a matrix to provide extended-release; the inactive ingredients include corn starch, hydroxypropyl methylcellulose, magnesium stearate, microcrystalline cellulose, povidone, silicon dioxide, and sodium alginate. This product complies with USP Drug Release Test 5. structure
What kind of drug is quinidine?
The FDA classifies quinidine as an antiarrhythmic. Antiarrhythmics steady an irregular heartbeat by controlling the flow of sodium, potassium, or calcium ions through heart-cell channels (or blunting adrenaline's effect), which slows or normalizes the heart's electrical signals so it beats in a more regular rhythm. If you are checking whether it is safe to combine with something else, the class is what matters — two drugs from the same class usually should not be stacked.
Can you take quinidine with other medicines?
It depends on the medicine. We check it against the FDA labels rather than guessing: our interaction checker searches each drug's own label for the other and quotes what it says, naming the section it came from. Run quinidine against whatever else you take — and remember that a label not naming a drug is not the same as that combination being safe.
What brand names is quinidine sold under?
We track 4 quinidine-containing products in the U.S.: Quinact, Quinidex, Quinidine Sulfate and Quinora. They are the same active ingredient; they differ in form, manufacturer, price and FDA recall record.
What forms does quinidine come in?
Across the brands we track, quinidine is currently marketed as tablet and tablet, extended release, per the FDA's National Drug Code Directory. Each form is dosed differently — follow the label for the exact product you were prescribed.
Sources: FDA openFDA drug label, National Drug Code Directory, and Enforcement (recall) database. This page reproduces public FDA data and is not medical advice. Dosing is set by your prescriber.
Who shouldn’t take quinidine
Quinidine is contraindicated in patients who are known to be allergic to it, or who have a history of immune thrombocytopenia or have developed thrombocytopenic purpura during prior therapy with quinidine or quinine (see WARNINGS ). In the absence of a functioning artificial pacemaker, quinidine is also contraindicated in any patient whose cardiac rhythm is dependent upon a junctional or idioventricular pacemaker, including patients in complete atrioventricular block. Quinidine is also contraindicated in patients who, like those with myasthenia gravis, might be adversely affected by an anticholinergic agent.
Quinidine drug interactions
Drug and Diet Interactions Altered pharmacokinetics of quinidine: Diltiazem significantly decreases the clearance and increases the t 1/2 of quinidine, but quinidine does not alter the kinetics of diltiazem. Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. By pharmacokinetic mechanisms that are not well understood, quinidine levels are increased by coadministration of amiodarone or cimetidine . Very rarely, and again by mechanisms not understood, quinidine levels are decreased by coadministration of nifedipine . Hepatic elimination of quinidine may be accelerated by coadministration of drugs ( phenobarbital, phenytoin, rifampin ) that induce production of cytochrome P450 IIIA4 . Perhaps because of competition for the P450 IIIA4 metabolic pathway, quinidine levels rise when ketoconazole is coadministered. Coadministration of propranolol usually does not affect quinidine pharmacokinetics, but in some studies the β-blocker appeared to cause increases in the peak serum levels of quinidine, decreases in quinidine's volume of distribution, and decreases in total quinidine clearance. The effects (if any) of coadministration of other β-blockers on quinidine pharmacokinetics have not been adequately studied. Hepatic clearance of quinidine is significantly reduced during coadministration of…
Yes. Our catalog lists 3 generic quinidine products alongside the brand versions. A generic has the same active ingredient and must meet the FDA's bioequivalence standard; it usually costs less. Ask your pharmacist which one your plan covers.