Quinidine sulfate

[KWIN-ih-deen] Pregnancy Category: C

Apo-Quinidine M, Quinidex Exten-tabs, Quinora [Rx] Classification: Antiarrhythmic, class IA_

See also Antiarrhythmic Agents. Action/Kinetics: Reduces the excitability of the heart and depresses conduction velocity and contractility. Prolongs the refractory period and increases conduction time. It also decreases CO and possesses anticholinergic, antimalarial, antipyretic, and oxytocic properties. PO: Onset: 0.5—3 hr. Maximum effects, after IM: 30-90 min. tvi: 6-7 hr. Time to peak levels, PO: 3-5 hr for Q gluconate salt, 1-1.5 hr for sulfate salt, and 6 hr for polygalacturonate salt; IM: 1 hr. Therapeutic serum levels: 2-6 mcg/mL. Protein binding: 60%-80%. Duration: 6-8 hr for tablets/capsules and 12 hr for extended-release tablets. Metabolized by liver. Urine pH affects rate of urinary excretion (10%-50% excreted unchanged).

Uses: Premature atrial, AV junctional, and ventricular contractions. Treatment and control of atrial flutter, established atrial fibrillation, paroxysmal atrial tachycardia, paroxysmal AV junctional rhythm, paroxysmal and chronic atrial fibrillation, paroxysmal ventricular tachycardia not associated with complete heart block, maintenance therapy after electrical conversion of atrial flutter or fibrilla tion. The parenteral route is indicated when PO therapy is not feasible or immediate effects are required. Non-FDA Approved Uses: Gluconate salt for life-threatening Plasmodium falcip-arum malaria.

Contraindications: Hypersensitiv-ity to drug or other cinchona drugs. Myasthenia gravis, history of thrombo-cytopenic purpura associated with quinidine use, digitalis intoxication evidenced by arrhythmias or AV conduction disorders. Also, complete heart block, left bundle branch block, or other intraventricular conduction defects manifested by marked QRS widening or bizarre complexes. Complete AV block with an AV nodal or idioventricular pacemaker, aberrant ectopic impulses and abnormal rhythms due to escape mechanisms. History of drug-induced torsades de pointes or long QT syndrome.

Special Concerns: Safety in children and during lactation has not been established. Quinidine should be used with extreme caution in clients in whom a sudden change in BP might be detrimental or in those suffering from extensive myocardial damage, subacute endocarditis, bradycardia, coronary occlusion, disturbances in impulse conduction, chronic valvular disease, considerable cardiac enlargement, frank CHF, and renal or hepatic disease. Cautious use is also recommended in clients with acute infections, hyper-thyroidism, muscular weakness, respiratory distress, and bronchial asthma. The dose in geriatric clients may have to be reduced due to age-related changes in renal function. Side Effects: CV: Widening of QRS complex, hypotension, cardiac asystole, ectopic ventricular beats, ventricular tachycardia or fibrillation, torsades de pointes, paradoxical tachycardia, arterial embolism, ventricular extrasystoles (one or more every 6 beats), prolonged QT interval, complete AV block, ventricular flutter. GI: N&V, abdominal pain, anorexia, diarrhea, urge to defecate as well as urinate, esophagitis (rare). CNS: Syn cope, headache, confusion, excitement, vertigo, apprehension, delirium, dementia, ataxia, depression. Dermatologic: Rash, urticaria, exfoli-ative dermatitis, photosensitivity, flushing with intense pruritus, eczema, psoriasis, pigmentation abnormalities. Allergic: Acute asthma, angion-eurotic edema, respiratory arrest, dyspnea, fever, vascular collapse, purpura, vasculitis, hepatic dysfunction (including granulomatous hepatitis), hepatic toxicity. Hematologic: Hypoprothrombinemia, acute hemo-lytic anemia, thrombocytopenic purpura, agranulocytosis, thrombocytope-nia, leukocytosis, neutropenia, shift to left in WBC differential. Ophthalmo-logic: Blurred vision, mydriasis, alterations in color perception, decreased field of vision, double vision, photophobia, optic neuritis, night blindness, scotomata. Other: Liver toxicity including hepatitis, lupus nephritis, tinnitus, decreased hearing acuity, arthritis, myalgia, increase in serum skeletal muscle CPK, lupus erythematosus. Drug Interactions Anticholinergic agents, Atropine / Additive effect on blockade of vagus nerve action

Barbiturates / i Effect of quinidine due to T breakdown by liver Cholinergic agents / Quinidine antagonizes effect of cholinergic drugs Neuromuscular blocking agents / T Respiratory depression Skeletal muscle relaxants / T Skeletal muscle relaxation Sodium bicarbonate / T Effect of quinidine due to i renal excretion Tricyclic antidepressants / T Effect of antidepressant due to i clearance How Supplied: Quinidine bisulfate: Sustained-release tablet: 250 mg. Quinidine gluconate: Injection: 80 mg/mL; Tablet, extended release: 324 mg. Quinidine polygalacturonate: Tablet: 275 mg. Quinidine sulfate: Tablet: 200 mg, 300 mg; Tablet, extended release: 300 mg

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