Antiarrhythmics

Question 1

Class Ia, Ib, and Ic antiarrhythmics block primarily which channels?

Answer 1

Na+ channels

Question 2

Quinidine, procainamide, disopyramide: Class, MOA

Answer 2

Class: Ia
MOA: Blocks Na and K channels = prolonged depolarization, prolonged QT interval (**risk for Torsades)
Decreases conduction velocity
Anticholinergic properties from K+blockade (disopyramide>quinidine»proc)

Question 3

AE of quinidine:

Answer 3

Diarrhea, nausea, HA, dizziness
Metabolized by CYP 450 systems
Increases dig levels (competes with enzymes)

Question 4

AE of procainamide:

Answer 4

Lupus-like syndrome, thromobcytopenia, neutropenia, anemia
Requires renal and hepatic adjustments
NAPA active metabolites (prolong effects)

Question 5

Which Class Ia antiarrhythmic should never be used with HF patients?

Answer 5

Disopyramide. It is a negative inotrope that depresses cardiac contractility

Question 6

Lidocaine, Mexilitine: Class, route of administraiton, MOA, met

Answer 6

Class Ib
Lidocaine- IV, Mexilitine- oral
MOA: Binds to both open and inactivated Na+ channels, shortens repolarization of QT interval (dec. likelihood of Torsades)
**Tx of ventricular arrhythmias (not SVT)
Metabolized by CYP 450

Question 7

AE of Lidocaine and Mexilitine:

Answer 7

Neurological- paresthesias, agitation, slurred speech, somnolence, confusion, psychosis, seizure

Question 8

Flecainide, propafenone, moricizone, encainide: class, MOA, AE

Answer 8

Class Ic
MOA: Most potent Na channel blockade
Depressive effects on cardiac function, proarrythmic effects
AE: sinus-node dysfunction, marked decrease in conduction velocity, conduction block, blurred vision, dizziness

Question 9

Class II Antiarrhythmics are also known as:

Answer 9

B-blockers

Question 10

Atenolol, metoprolol, acebutolol, bisoprolol, esmolol: Class, MOA, AE

Answer 10

Class II
Block sympathetic stimulation of B-1 receptors in the SA and AV nodes (rate control)
Negative inotropic effect, slows SA node firing and conduction throughout AV node
Decrease rate of depolarization, prolongs repolarization

Overall: Decreases cardiac contractility and slows HR

AE: Excessive neg. inotropic effects, HB, brady, bronchospasm (off target), insomnia

Question 11

Class III Antiarrythmics primarily affect:

Answer 11

K channels

Question 12

Sotalol: Class, MOA, AE

Answer 12

Class III
Block K channels= prolong repolarization
Also blocks beta receptors
Treatment for ventricular arrhythmias and prevention of Afib/flutter
AE: bradycardia, fatigue, Torsades

Question 13

Amniodarone: Class, MOA

Answer 13

Class III
Blocks K channels prolonging repolarization
Also blocks Ca, K, and beta receptors
Treatment of ventricular and atrial arrhythmias

Question 14

Dronedarone: Class III

Answer 14

Class III
Blocks K channels prolonging repolarization
Similar to amniodarone but less liphophilic= shorter half-life and does not contain iodine which decreases AE
Caution with systolic HF
May causes hepatotoxicity

Question 15

Amniodarone AE:

Answer 15

Decreased AV/SA node function, bradycardia
Pneumonitis, pulmonary fibrosis, toxicity
Hyper or hypo- thyroidism
Elevated LFTs
Corneal microdeposits, optic neuritis
Peripheral neuropathy, HA, ataxia, tremors, skin discoloration (blue apppearing), GI upset, photosensitivity
Several CYP 450 interactions (including warfarin)

R/t idoine content and long half life 20-50days (prolong AE but not pharm effects)

Need routine LFTs, TFTs, pulm test, opthalmic exams

Question 16

Ibutilide and Dofetilide:

Answer 16

Class III antiarrythmic
Blocks K channels prolonging repolarization
Ibutelide-IV
Dofetilide-Oral (must be monitored inpatient for 72hrs)
Effective for chemical cardioversion in setting of Afib/Aflutter
Can causes Torsades (monitor inpatient, monitor K, Mag?

**Dofetilide= practitioner and pt must register with company for continued monitoring

Question 17

Class IV Antiarrhythmics are also known as_______.

Answer 17

CCB

Verapamil and diltiazam

Question 18

Verapamil and Dilt: MOA, Use

Answer 18

MOA: Decrease flow of Ca into cardiac cells
Slowed firing of SA node
Slowed conduction of AV node
Negative inotropic effect
Use: Treatment of SVT and rate control for afib/aflutter
**Not for ventricular arrhythmias

Question 19

Verapamil and Dilt AE:

Answer 19

May increase dig levels

Bradycardia, excess AV block, HF, Hypotension, constipation(verapamil)