Quinidine

A to Z Drug Facts

(KWIN-ih-deen)

Quinidine Sulfate

Quinidex Extentabs, Quinora,  Apo-Quinidine

Quinidine Gluconate

Quinaglute Dura-Tabs, Quinalan,  Quinate

Quinidine Polygalacturonate

Cardioquin

Class: Antipsychotic

 Action Depresses myocardial excitability, conduction velocity and contractility; prolongs effective refractory period and increases conduction time; indirect anticholinergic effects; may decrease vagal tone at low doses paradoxically increasing conduction through the AV node.

 Indications Treatment of premature atrial, atrioventricular junctional, and ventricular contractions; treatment of paroxysmal supraventricular tachycardia, paroxysmal atrioventricular junctional rhythm, atrial flutter, paroxysmal and chronic atrial fibrillation, and paroxysmal ventricular tachycardia not associated with complete heart block; maintenance therapy after electrical conversion of atrial fibrillation or flutter.

Quinidine gluconate (IV administration): Treatment of life-threatening Plasmodium falciparum malaria.

 Contraindications Myasthenia gravis; history of thrombocytopenic purpura associated with quinidine administration; digitalis intoxication; complete heart block; left bundle branch block; complete atrioventricular (AV) block with AV nodal or idioventricular pacemaker; aberrant ectopic impulses and abnormal rhythms because of escape mechanisms; history of drug-induced torsade de pointes; history of long QT syndrome.

 Route/Dosage

The following oral doses are expressed as quinidine sulfate salt:

Premature Atrial and Ventricular Contractions

ADULTS: PO 200 to 300 mg tid/qid. CHILDREN: PO 30 mg/kg/day or 900 mg/m ²/day in 5 divided doses.

Paroxysmal Supraventricular Tachycardia

ADULTS: PO 400 to 600 mg q 2 to 3 hr until event is abated.

Atrial Flutter

Administer after digitalization and individualize dose.

Conversion of Atrial Fibrillation

ADULTS: PO 200 mg q 2 to 3 hr for 5 to 8 doses, then maintain with 200 to 300 mg tid to qid (immediate-release tablets) or 300 to 600 mg bid to tid (sustained-release tablets); do not exceed 3 to 4 g/day.

QUINIDINE GLUCONATE

ADULTS: PO 324 to 648 mg (1 to 2 tablets) q 8 to 12 hr.

Quinidine Polygalacturonate

ADULTS: PO Maintenance dose: 275 mg q 8 to 12 hr.

PARENTERAL QUINIDINE GLUCONATE

ACUTE TACHYCARDIA: ADULTS: IM 600 mg initially, then 400 mg prn up to q 2 hr. CHILDREN: IV 2 to 10 mg/kg/dose q 3 to 6 hr prn. P. FALCIPARUM MALARIA: ADULTS: IV 15 mg/kg infused over 4 hr initially, then 7.5 mg/kg over 4 hr q 8 hr for 7 days or until oral therapy can be instituted or 10 mg/kg over 1 to 2 hr initially, then 0.02 mg/kg/min for up to 72 hr or until oral therapy can be instituted.

 Interactions

Amiodarone, antacids, cimetidine, verapamil: May increase quinidine levels. Anticoagulants: May increase effect of anticoagulant; may cause hemorrhage. Barbiturates, nifedipine, primidone, sucralfate: May decrease quinidine levels. Beta-blockers: May increase effect of beta-blocker. Dextromethorphan: May increase plasma dextromethorphan concentrations. Digitoxin, digoxin: May increase digoxin plasma levels. Hydantoins: May reduce therapeutic effect of quinidine. Nondepolarizing neuromuscular blocking agents, succinylcholine: May increase neuromuscular blockade effect. Propafenone: Increased propafenone levels. Rifampin: May increase quinidine metabolism.

 Lab Test Interferences Triamterene will interfere with the fluorescent measurement of quinidine levels.

 Adverse Reactions

CV: Widening of QRS complex; cardiac asystole; ventricular ectopy; hypotension; paradoxical tachycardia. CNS: Headache; fever; vertigo; excitement; confusion; delirium; syncope. DERM: Rash; urticaria; pruritus; flushing; photosensitivity. EENT: Mydriasis; blurred vision; photophobia, diplopia, night blindness; tinnitus. GI: Nausea; vomiting; anorexia; abdominal pain; diarrhea. GU: Lupus nephritis. HEPA: Hepatitis. HEMA: Acute hemolytic anemia; agranulocytosis; thrombocytopenic purpura. OTHER: Lupus erythematosus-like syndrome; cinchonism (headache, tinnitus, nausea, disturbed vision, deafness, dizziness, vertigo, lightheadedness); hypersensitivity reactions; arthralgia; myalgia.

 Precautions

Pregnancy: Category C. Lactation: Excreted in breast milk. Children: Safety and efficacy not established. Atrial flutter or fibrillation: Pretreat these patients with digitalis preparation. Bioequivalency: Different salts have different amounts of quinidine base. Do not interchange without taking this into consideration. Cardiotoxicity: May occur; immediately discontinue drug. Hepatotoxicity (including granulomatous hepatitis): Has occurred. Consider possibility if unexplained fever or elevated hepatic enzymes develop. Hypersensitivity reactions: May occur; administer single 200 mg tablet of quinidine sulfate or 200 mg IM injection of quinidine gluconate before starting therapy to determine if patient has idiosyncrasy to quinidine. Malaria: Dose schedules may result in hypotension, ECG changes, and cinchonism. Parenteral therapy: Use only when oral therapy is not possible or when rapid therapeutic effect is required. Potassium balance: Effect of quinidine is enhanced by potassium and reduced if hypokalemia is present. Renal, hepatic, or cardiac impairment: Use drug with caution because of potential for toxicity. Syncope: Occasionally occurs in patients on long-term therapy; may be fatal. Often caused by torsades de pointes. Vagolytic effects: May antagonize vagal maneuvers or administration of cholinergic drugs used to terminate paroxysmal supraventricular tachycardia.

 Administration/Storage

• Use IV route only when rapid response is needed or oral route is not feasible.
• Give test dose of 200 mg as ordered to evaluate intolerance/sensitivity.
• Position patient supine during IV administration to minimize hypotension.
• For direct IV push, administer slowly at 1 ml/min.
• For intermittent IV infusion, dilute 800 mg/50 ml or more with D5W; give at a rate of 16 mg/min or less. Use infusion device for accuracy/safety.
• Administer IM injection in deltoid muscle.
• Give oral preparation with full glass of water on empty stomach (1 hr before or 2 hr after other medication) to enhance absorption; if GI distress develops, administer with or just after meal.
• Do not break or crush or allow patient to chew sustained-release preparations. Instruct patient to swallow whole.
• Store vial at room temperature. Parenteral solution must be clear and colorless. Solution is stable for 24 hr.
• Store tablets in tight, light-resistant container.

 Assessment/Interventions

• Obtain patient history, including drug history and any known allergies.
• Determine if patient has myasthenia gravis.
• When drug is used as antiarrhythmic agent, assess ECG prior to and continuously throughout therapy. Therapy is discontinued if severe heart block occurs (50% widening of QRS complex, PR, or QT interval are prolonged) or tachycardia or frequent ventricular ectopic beats develops.
• Obtain baseline BP and pulse and assess continuously during therapy.
• Monitor CBC and hepatic and renal function tests during long-term therapy.
• When drug is used as antimalarial agent, monitor BP, ECG, and plasma quinidine levels closely during therapy, especially if drug is being administered parenterally.
• If patient had been receiving digoxin, measure digoxin concentration to ensure it does not increase to toxic levels.
• Observe for hypotension, tachycardia, and arrhythmias.

 Patient/Family Education

• Instruct patient/family to administer medication around clock as directed and to continue taking medication even if symptoms improve.
• Advise patient to take with food if GI upset occurs.
• Tell patient that sustained-release tablet should not be crushed or chewed.
• Instruct patient/family how to take pulse. Advise them to check pulse prior to each dose and to contact health care provider if rate or rhythm changes.
• Advise patient to carry identification (eg, Medi-Alert) indicating disease and drug therapy at all times.
• Advise patient to notify other health care providers/dentist prior to other therapy/surgery.
• Emphasize importance of regular medical follow-up, even in absence of side effects or problems related to this drug therapy.
• Caution patient to wear dark glasses as needed to decrease light sensitivity and inform patient that dark glasses may be needed both indoors and outside.
• Instruct patient to report these symptoms to health care provider immediately: Visual disturbances (eg, blurring), tinnitus, bleeding, bruising, fever, headache, dizziness, severe diarrhea, or skin rash/eruption.
• Advise patient that drug causes dizziness and blurred vision and to use caution while driving or performing other tasks requiring mental alertness.
• Caution patient to avoid exposure to sunlight and to use sunscreen or wear protective clothing to avoid photosensitivity reaction.
• Instruct patient not to take otc medications without consulting health care provider.

Books@Ovid
Copyright © 2003 Facts and Comparisons
David S. Tatro
A to Z Drug Facts