Anti-arrhythmic Meds

Question 1

Quinidine

MOA:

Uses:

ADRs:

Metabolism:

CI:

Drug Interactions:

Answer 1

Quinidine

MOA: Blocks Na+ and K+ channels → Prolongs AP and QT interval

Uses: Atrial/ventricular arrhythmias

ADRs: Cinchonism (tinnitus, headache), QT prolongation → Torsades de Pointes (TdP), thrombocytopenia

Metabolism: Hepatic

CI: Long QT syndrome, thrombocytopenia

Drug Interactions: Inhibits CYP2D6, interacts with digoxin

Question 2

Procainamide

MOA:

Uses:

ADRs:

Metabolism:

CI:

Drug Interactions:

Answer 2

Procainamide

MOA: Blocks Na+ and K+ channels, prolongs AP

Uses: Atrial/ventricular arrhythmias, WPW syndrome

ADRs: Drug-induced lupus, agranulocytosis, QT prolongation → TdP

Metabolism: Hepatic (N-acetylation), renal excretion

CI: Myasthenia gravis, QT prolongation

Drug Interactions: Minimal

Question 3

Disopyramide

MOA:

Uses:

ADRs:

Metabolism:

CI:

Drug Interactions:

Answer 3

Disopyramide

MOA: Na+ channel blocker with strong anticholinergic effects

Uses: Ventricular arrhythmias

ADRs: Anticholinergic (dry mouth, urinary retention), negative inotropy → HF exacerbation

Metabolism: Hepatic, renal excretion

CI: Heart failure, cardiogenic shock

Drug Interactions: CYP3A4 substrate

Question 4

Lidocaine

MOA:

Uses:

ADRs:

Metabolism:

CI:

Drug Interactions:

Answer 4

Lidocaine

MOA: Preferentially blocks inactivated Na+ channels in ischemic myocardium

Uses: Acute ventricular arrhythmias (post-MI), digitalis-induced arrhythmias

ADRs: CNS toxicity (seizures, confusion, paresthesia)

Metabolism: Hepatic

CI: Heart block, severe hepatic disease

Drug Interactions: Minimal

Question 5

Mexiletine

MOA:

Uses:

ADRs:

Metabolism:

CI:

Drug Interactions:

Answer 5

Mexiletine

MOA: Oral analog of lidocaine, preferentially affects ventricular arrhythmias

Uses: Chronic ventricular arrhythmias

ADRs: Tremor, nausea, dizziness, Hypersensitivity Rxns

Metabolism: Hepatic (CYP1A2 inhibition)

CI: Cardiogenic shock

Drug Interactions: CYP1A2 inhibitor

Question 6

Flecainide

MOA:

Uses:

ADRs:

Metabolism:

CI:

Drug Interactions:

Answer 6

Flecainide

MOA: Strong Na+ channel blockade → Slows conduction

Uses: Supraventricular tachycardia, AFib

ADRs: Proarrhythmic, especially post-MI (CI in ischemic heart disease)

Metabolism: Renal and hepatic

CI: Structural heart disease, MI

Drug Interactions: CYP2D6 substrate

Question 7

Propafenone

MOA:

Uses:

ADRs:

Metabolism:

CI:

Drug Interactions:

Answer 7

Propafenone

MOA: Strong Na+ channel blockade, weak beta-blocker activity

Uses: AFib, SVT

ADRs: Bradycardia, bronchospasm (due to beta-blockade), Metallic Taste

Metabolism: Hepatic (CYP2D6)

CI: Uncontrolled heart failure, asthma

Drug Interactions: CYP2D6 substrate

Question 8

Propranolol, Metoprolol, Esmolol, Atenolol

MOA:

Uses:

ADRs:

Metabolism:

CI:

Drug Interactions:

Answer 8

Propranolol, Metoprolol, Esmolol, Atenolol

MOA: Selective B1 Blocker, Decrease SA/AV node activity by decreasing cAMP and Ca2+ currents

Uses: Rate control in AFib, SVT, post-MI arrhythmias

ADRs: Bradycardia, bronchospasm (non-selective), fatigue

Metabolism: Hepatic (except esmolol, which is rapidly hydrolyzed)

CI: Asthma (non-selective agents), severe bradycardia

Drug Interactions: Additive effects with other AV nodal blockers

Question 9

Amiodarone

MOA:

Uses:

ADRs:

Metabolism:

CI:

Drug Interactions:

Answer 9

Amiodarone

MOA: Blocks K+, Na+, Ca2+, and beta receptors

Uses: AFib, VT, WPW

ADRs: Pulmonary fibrosis, hepatotoxicity, thyroid dysfunction, corneal deposits

Metabolism: Hepatic (CYP3A4), very long half-life (~50 days)

CI: Severe lung/liver disease

Drug Interactions: Inhibits CYP3A4, CYP2C9, P-gp

Question 10

Sotalol, Dofetilide, Ibutilide

MOA:

Uses:

ADRs:

Metabolism:

CI:

Drug Interactions:

Answer 10

Sotalol, Dofetilide, Ibutilide

MOA: Prolongs repolarization via K+ channel blockade

Uses: AFib, atrial flutter, VT

ADRs: QT prolongation → TdP

Metabolism: Renal (Sotalol, Dofetilide), Hepatic (Ibutilide)

CI: QT prolongation, renal dysfunction

Drug Interactions: Additive QT prolongation

Question 11

Verapamil, Diltiazem

MOA:

Uses:

ADRs:

Metabolism:

CI:

Drug Interactions:

Answer 11

Verapamil, Diltiazem

MOA: Blocks L-type Ca2+ channels → Slows AV conduction

Uses: SVT, rate control in AFib

ADRs: Constipation (verapamil), hypotension, bradycardia

Metabolism: Hepatic

CI: Heart block, severe HF

Drug Interactions: Additive AV block with beta-blockers/digoxin

Question 12

Digoxin

MOA:

Uses:

ADRs:

Metabolism:

CI:

Drug Interactions:

Answer 12

Digoxin

MOA: Inhibits Na+/K+ ATPase → Increased intracellular Ca2+

Uses: AFib (rate control), heart failure

ADRs: Nausea, arrhythmias, vision disturbances

Metabolism: Renal excretion

CI: Ventricular fibrillation, hypokalemia

Drug Interactions: CYP3A4, P-gp interactions

Question 13

Adenosine

MOA:

Uses:

ADRs:

Metabolism:

CI:

Drug Interactions:

Answer 13

Adenosine

MOA: Activates K+ channels → Hyperpolarizes AV node

Uses: Acute SVT termination

ADRs: Flushing, chest tightness, dyspnea

Metabolism: Very short half-life (~10 sec)

CI: Heart block, asthma

Drug Interactions: Effects blocked by theophylline, enhanced by dipyridamole

Question 14

Magnesium Sulfate

MOA:

Uses:

ADRs:

Metabolism:

CI:

Drug Interactions:

Answer 14

Magnesium Sulfate

MOA: Stabilizes cardiac membranes, prevents TdP

Uses: Torsades de Pointes, digoxin toxicity

ADRs: Hypotension, decreased reflexes

Metabolism: Renal

CI: Renal failure

Drug Interactions: Minimal