Anti-arrhythmic Drug Pharmacology

Question 1

What are Class I agents?

Answer 1

They are Na transport blockers.

Question 2

What do Class 1a drugs do?

Answer 2

Lengthen the AP

Question 3

What do Class 1b drugs do?

Answer 3

Shortens action potential

Question 4

What do Class 1c drugs do?

Answer 4

No effect on duration of AP but reduces the amplitude of the AP

Question 5

What are Class 2 agents?

Answer 5

β-Blockers.
Has predominant action of the sinus node.
(Propranolol, esmolol, atenolol, bisoprolol)

Question 6

What does Class 2 drugs do?

Answer 6

Causes hyperpolarisation of the pacemaker potentials so it takes longer for a heart beat to occur which causes a reduction in heart rate.

Question 7

What are Class 3 agents?

Answer 7

K+ channel blockers
(Soltalol) ventricular tachycardia & AF
(Ibutilide) Atrial flutter & AF

Question 8

What do Class 3 drugs do?

Answer 8

Work on the cardiomyocytes cells to increase the length of the AP.

Question 9

What are Class 4 agents?

Answer 9

CCB
Verapamil , Diltiazem

Question 10

What do Class 4 drugs do?

Answer 10

Prevent further recurrence of paroxysmal super ventricular tachy
Decreases rate in PT with atrial fibrillation.

Question 11

What are non-Vaughen William antiarrhythmic drugs?

Answer 11

Adenosine, Digoxin, magnesium sulphate.
Used in super ventricular arrhythmias, especially in HF with AF
C/I in ventricular arrhythmias

Question 12

How does Digoxin work?

Answer 12

–| of Na/K ATPase pump
- Increases Na[ ] inside the cell
- Increases the exchange of Na for Ca
- Increases intracellular Ca
- Increases influx of Ca from sarcoplasmic reticulum
- Increases the contractility of cardiac muscle.

Question 13

How does adenosine work?

Answer 13

Decreases firing of SA node