AntiArrhythmic Classes

Question 1

Class 1 are?

Answer 1

antiarrhythmic drugs are sodium channel blockers

Question 2

Class 1A MOA and example drug

Answer 2

Depress phase 0 and prolong the action potential duration
-Disopyramide

Question 3

Disopyramide MOA

Answer 3

Depresses phase 0 and prolongs the action potential duration.

Question 4

Disopyramide side effects

Answer 4

Dry mouth, constipation, urinary retention, hypotension

Question 5

Contraindications of Disopyramide

Answer 5

Cardiogenic shock, second- or third-degree AV block (without pacemaker)

Question 6

Class 1B MOA and example drug

Answer 6

Depress phase 0 slightly and may shorten the action potential duration
-Mexiletine
block both activated and inactivated sodium channels

Question 7

Class 1C MOA and example drug

Answer 7

primarily block the sodium fast channel during phase 0 of the action potential

-Flecainide
-Propafenone

Depress phase 0. Slowing of conduction

Question 8

Class II MOA and example drug

Answer 8

BetaBlockers: reduce adrenergic activity in the heart. Blockade by these drugs increases threshold potential and prolongs ERP, thereby decreasing heart rate and conduction velocity.

Depress phase 4 depolarization
- propranolol

Question 9

Class III MOA and example drug

Answer 9

Produce a prolongation of phase 3 (repolarization)
o Amiodarone
o Dronedarone
o Sotalol
prolong the ERP by some mechanism other than sodium channel blockade, often by blocking potassium channels, which results in a decreased rate of automaticity of ventricular ectopic beats

Question 10

Class IV MOA and example drug

Answer 10

Depress phase 4 depolarization and lengthen phases 1 and 2 of repolarization.
-Diltiazim
-Verapamil
They are good for rate control, increasing O2 supply via vasodilation and afterload reduction

Question 11

Half life of Amio

Answer 11

26 or more days for amiodarone.

Question 12

Thyroid effects of Amio

Answer 12

Amiodarone inhibits the enzyme that converts T4 to T3, and iodine is a major component of this drug; therefore, about 5% of patients with underlying predisposition to thyroid disease may develop thyrotoxicosis or hypothyroidism.

Question 13

The NP orders a thyroid panel for a patient on amiodarone. The patient tells the NP that he does not have thyroid disease and wants to know why the test is ordered. Which is a correct response?
1. Amiodarone inhibits an enzyme that is important in making thyroid hormone and
can cause hypothyroidism.
2. Amiodarone damages the thyroid gland and can result in inflammation of that
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gland, causing hyperthyroidism.
3. Amiodarone is a broad spectrum drug with many adverse effects. Many different
tests need to be done before it is given.
4. Amiodarone can cause corneal deposits in up to 25% of patients

Answer 13

1. Amiodarone inhibits an enzyme that is important in making thyroid hormone and
   can cause hypothyroidism.