(kwin'i-deen sul-fate)
Apo-Quinidine , Novoquinidin , Quinidex Extentabs, Quinora
Quinaglute Duratabs
Classifications: cardiovascular agent; antiarrhythmic class ia
Prototype: Procainamide
Pregnancy Category: C


Quinidine sulfate 200 mg, 300 mg tablets; 300 mg sustained release tablets

Quinidine gluconate 324 mg sustained release tablets; 80 mg/mL injection

Quinidine polygalacturonate 275 mg tablets


Dextro-isomer of quinine and alkaloid of Cinchona. Class I-A antiarrhythmic. Cardiac actions similar to those of procainamide. Depresses myocardial excitability, contractility, automaticity, and conduction velocity, and prolongs effective refractory period. Anticholinergic action blocks vagal stimulation of AV node, thus tending to increase ventricular rate, particularly in larger doses.

Therapeutic Effects

Depresses myocardial excitability, conduction velocity, and irregularity of nerve impulse conduction.


Premature atrial, AV junctional, and ventricular contraction; paroxysmal atrial tachycardia, chronic ventricular tachycardia (when not associated with complete heart block); maintenance therapy after electrical conversion of atrial fibrillation or flutter.

Unlabeled Uses

Quinidine gluconate for severe malaria.


Hypersensitivity or idiosyncrasy to quinine or Cinchona derivatives; pregnancy (category C), lactation. Thrombocytopenic purpura resulting from prior use of quinidine; intraventricular conduction defects, complete AV block, ectopic impulses and rhythms due to escape mechanisms; thyrotoxicosis; acute rheumatic fever; subacute bacterial endocarditis, extensive myocardial damage, frank CHF, hypotensive states; myasthenia gravis; digitalis intoxication.

Cautious Use

Incomplete heart block; impaired kidney or liver function; bronchial asthma or other respiratory disorders; myasthenia gravis; potassium imbalance.

Route & Dosage

Ectopic Beats Sulfate
Adult: PO 200–300 mg t.i.d. or q.i.d.
Child: PO 6 mg/kg 5 times/d

Ventricular Arrhythmias Sulfate
Adult: PO 400–600 mg q2–3h until arrhythmia terminates, then 200–300 mg 3–4 times/d

Atrial Fibrillation or Flutter Sulfate
Adult: PO 200 mg q2–3h for 5–8 doses until sinus rhythm restored or toxicity occurs (max: 3–4 g), then 200–300 mg t.i.d. or q.i.d.

Adult: PO 275–825 mg q3–4h for 4 or more doses until arrhythmia terminates, then 137.5–275 mg b.i.d. or t.i.d.

Acute Tachycardia Gluconate
Adult: PO 324–660 mg q8–12h IM 600 mg, then 400 mg q2h prn IV 200–750 mg at a rate of 16 mg/min


Note: Sulfate contains 83% anhydrous quinidine base; polygalacturonate, 80%; and gluconate, 62%. Examine parenteral solution before preparation; use only if clear and colorless.


PREPARE: IV Infusion: Dilute 800 mg (10 mL) in at least 40 mL D5W to yield a maximum concentration of 16 mg/mL.  

ADMINISTER: IV Infusion: Give via infusion pump at a rate not to exceed 16 mg (1 mL)/min.  

INCOMPATIBILITIES Solution/additive: Amiodarone, atracurium. Y-site: Furosemide, heparin in dextrose.

  • Use supine position during drug administration; severe hypotension is most likely to occur in patients receiving drug via IV.
  • Protect IV solutions from light and heat to prevent brownish discoloration and possibly precipitation.

Adverse Effects (1%)

CNS: Headache, fever, tremors, apprehension, delirium, syncope with sudden loss of consciousness, seizures. CV: Hypotension, CHF, widened QRS complex, bradycardia, heart block, atrial flutter, ventricular flutter, fibrillation or tachycardia; quinidine syncope, torsades de pointes. Special Senses: Mydriasis, blurred vision, disturbed color perception, reduced visual field, photophobia, diplopia, night blindness, scotomas, optic neuritis, disturbed hearing (tinnitus, auditory acuity). GI: Nausea, vomiting, diarrhea, abdominal pain, hepatic dysfunction. Hematologic: Acute hemolytic anemia (especially in patients with G6PD deficiency), hypoprothrombinemia, leukopenia. Thrombocytopenia, agranulocytosis (both rare). Body as a Whole: Cinchonism (nausea, vomiting, headache, dizziness, fever, tremors, vertigo, tinnitus, visual disturbances), angioedema, acute asthma, respiratory depression, vascular collapse. Skin: Rash, urticaria, cutaneous flushing with intense pruritus, photosensitivity. Metabolic: SLE, hypokalemia.


Drug: May increase digoxin levels by 50%; amiodarone may increase quinidine levels, thus increasing its risk of heart block; other antiarrhythmics, phenothiazines, reserpine add to cardiac depressant effects; anticholinergic agents add to vagolytic effects; cholinergic agents may antagonize cardiac effects; anticonvulsants, barbiturates, rifampin increase the metabolism of quinidine, thus decreasing its efficacy; carbonic anhydrase inhibitors, sodium bicarbonate, chronic antacids decrease renal elimination of quinidine, thus increasing its toxicity; verapamil causes significant hypotension; may increase hypoprothrombinemic effects of warfarin. Diltiazem may increase levels and decrease elimination of quinidine.


Absorption: Almost completely absorbed from GI tract. Onset: 1–3 h. Peak: 0.5–1 h. Duration: 6–8 h. Distribution: Widely distributed to most body tissues except the brain; crosses placenta; distributed into breast milk. Metabolism: Metabolized in liver. Elimination: >95% excreted in urine, <5% in feces. Half-Life: 6–8 h.

Nursing Implications

Assessment & Drug Effects

Patient & Family Education

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug