Antiarrhythmics

Question 1

Digoxin

Answer 1

Cardiac glycoside, Na/K ATPase inhibitor
Admin: oral
Uses: CHF, atrial tachycardia
Toxicity: arrhythmias, vision changes

Question 2

Procainamide

Answer 2

Class IA antiarrhythmic, Na+ channel inhibitor
Admin: oral, IV
Uses: atrial and ventricular tachycardias, broad spectrum
Toxicity: cardiac toxicity, hypersensitivity reactions with chronic use

Question 3

Quinidine

Answer 3

Class IA antiarrhythmic, Na+ channel inhibitor, anti-muscarinic activity
Admin: oral
Uses: atrial and ventricular tachycardias, broad spectrum
Toxicity: arrhythmias, diarrhea, headache, tinnitus
Low therapeutic index due to cardiac effects

Question 4

Lidocaine

Answer 4

Class IB antiarrhythmic, Na+ channel inhibitor
Admin: IV (short half life)
Uses: ventricular arrhythmias in surgery and ICU (NOT supraventricular arrhythmias)
Toxicity: drawsiness, irritability, convulsions
High therapeutic index

Question 5

Mexiletine

Answer 5

Class IB antiarrhythmic, Na+ channel inhibitor
Admin: oral (lidocaine analogs with longer half lives)
Uses: ventricular arrhythmias, digoxin-induced arrhythmias (NOT supraventricular arrhythmias)
Toxicity: CNS

Question 6

Flecainide

Answer 6

Class IC antiarrhythmic, Na+ channel inhibitor
Admin: oral
Uses: atrial tachycardias in patients with normal ventricular function
Toxicity: arrhythmias, sudden cardiac death in patients with previous MI

Question 7

Propranolol

Answer 7

Class II antiarrhythmic, beta antagonist
Admin: oral
Uses: atrial and ventricular tachycardias

Question 8

Metoprolol

Answer 8

Class II antiarrhythmic, beta antagonist
Admin: oral
Uses: atrial tachycardia

Question 9

Amiodarone

Answer 9

Class III antiarrhythmic, K+ and Na+ channel inhibitor
Admin: oral
Uses: recurrent ventricular tachycardia or fibrillation (high dose), atrial tachycardia in patients resistant to other drugs (lower dose)
Toxicity: prolonged QT, hypotension, pulmonary fibrosis, tissue deposits, drug interactions
Poor oral absorption and bioavailability; loading dose needed

Question 10

Dronaderone

Answer 10

Class III antiarrhythmic, K+ and Na+ channel inhibitor
Admin: oral
Uses: atrial and ventricular arrhythmias
Toxicity: prolonged QT, depressed conduction (lower frequency than amiodarone)

Question 11

Dofetilide

Answer 11

Class III antiarrhythmic, K+ channel inhibitor (repolarization current)
Admin: oral
Uses: atrial arrhythmias
Toxicity: prolonged QT, ventricular arrhythmia
Prolongs AP duration and effective refractory period, patients carefully monitored via ECG when used

Question 12

Sotalol

Answer 12

Class III antiarrhythmic, K+ channel inhibitor and beta antagonist
Admin: oral
Uses: atrial and ventricular arrhythmias (decreases SA nodal automaticity and slows AV node conduction)
Toxicity: prolonged QT, arrhythmogenic
Prolongs AP duration and effective refractory period, only racemic mixture is used

Question 13

Verapamil

Answer 13

Class IV antiarrhythmic, voltage gated Ca2+ channel inhibitor (cardiac selective)
Admin: oral
Uses: atrial arrhythmias > angina and hypertension, supraventricular arrhythmias only (flutter, Afib, paroxysmal SVT)
Toxicity: hypotension, tachycardia
Slowed AV nodal conduction, increased effective refractory period

Question 14

Diltiazem

Answer 14

Class IV antiarrhythmic, voltage gated Ca2+ channel inhibitor (cardiac selective)
Admin: oral
Uses: atrial arrhythmias > angina and hypertension, supraventricular arrhythmias only (flutter, Afib, paroxysmal SVT)
Toxicity: hypotension, tachycardia

Question 15

Nifedipine

Answer 15

Antihypertensive, voltage gated Ca2+ channel inhibitor (vascular smooth muscle selective)
Admin: oral
Uses: angina, hypertension
Toxicity: hypotension, tachycardia
Not useful for arrhythmias

Question 16

Adenosine

Answer 16

Activate adenosine receptors (antagonist of sympathetic tone)
Admin: IV
Uses: acute conversion of re-entrant SVT (NOT Afib)
Rapid onset, slows AV nodal conduction and increases AV nodal effective refractory period