Class II and IV Antiarrythmics

Question 1

What is the main effect of class III antiarrhythmic agents?

Answer 1

Class III agents prolong the repolorizing phase of Phase 3 in the myocardium.

It does this by blocking potassium channels.

Question 2

What channels are blocked by Amiodarone?

Answer 2

Amiodarone works by blocking potassium, sodium, and calcium channels to slow conduction through the AV node.

It also acts by noncompetitively blocking alpha, beta and muscarinic receptors.

Question 3

What is the drug of choice in the Class III drugs used to slow Afib while maintaining sinus rhythm?

Answer 3

Amiodarone.

Question 4

What problems can Amiodarone be used to treat?

Answer 4

Used to treat Afib by controling rhythmn

Controls AV nodal reentrant tachycardia.

IV for acute termination of Ventricular tachycardia or Ventricular fibriliation.

Replacing lidocaine for termination of cardiac arrest

Question 5

Why can early arrythmias occur in amiodarone therapy if it is discontinued too soon/

Answer 5

Amiodarone takes 13-103 days to saturate all of the tissues.
Thus if the drug is stopped too soon it can work its way out of the heart.

Question 6

What are the side effects caused by amioderone?

Hint 3 main ones

Answer 6

Lethal pulmonary fibrosis

Hyerthyroidism or Hypothyroidism

Elevated Serum Hepatic enzyme levels.

Minor: Accumulation of corneal microdeposits and photosensitivity with blue/gray skin deposits.

Question 7

What tests should be ran when using amiodarone?

Answer 7

Pulmonary Function tests
Thyroid function tests
Liver function tests.

Question 8

What is the mechanism of action for the Class III drug Ibutilide?

Answer 8

Blocks delayed rectifier potassium current to slow cardiac repolarization. Activates slow inward sodium current prolonging the AP.

Question 9

What is the indicated use for the drug ibutilide?

Answer 9

Ibutilide is used for atrial FLUTTER

It can also be used for atrial fibrillation.

Question 10

What are the potential side efffects of Ibutilide?

Answer 10

Ibutilide can lead to torsades de pointes.

Question 11

What is the mechanism of action for the class III drug Dofetilide?

Answer 11

This drug is a dose dependent blocker of the delayed rectifier K+ current.

It does not block other K+ channels.

Question 12

What is the medical use of Dofetilide and what class of antiarrythmics is it?

Answer 12

Class III

Used to restore normal RHYTHM in patients with Afib.

Question 13

What is the side effect of the drug dofetilide?

Answer 13

This drug can prolong the QT interval and lead to ventricular arrythmias.

Question 14

What is the mechanism of action for the drug sotalol?

Answer 14

Sotalol is a class III antiarrythmic that works by blocking potassium channels and prolonging the action potential..

Iteresting enough it has Beta blocking properties as well.

Question 15

What are the uses for the drug Stalol and what are the possible side effects?

Answer 15

Sotalol is a Class III antiarythmic.

Used for life threatening ventricular arrythmias.

Can cause DOSE RELATED TORSADES DE POINTES.

Question 16

In general what do Class IV antiarrhythmic drugs do?

Answer 16

these are calcium channel antagonists.

thus these primarily effect phase 0 depolarization slowing SA automaticity and AV nodal conduction. decreasing ventricular contractility.

Question 17

In general, what function do class IV antiarrythmics have?

Answer 17

These drugs are calcium channel antagonists!

Work by effecting phase 0 depolarization supressing SA nodal automaticity, AV nodal conduction and ventricular contractility.

Question 18

What two drugs fit within the non-dihydropyridine class of calcium channl blockers?

Answer 18

Verapamil and Dilitizem` working mostly in the heart.

Question 19

What should be known about the calcium channel blocker Nifedipine?

Answer 19

Nifedipine is a DHP calcium channel blocker and works mostly by dilating arterial vessels in the periphary.

Question 20

Just for fun haha what are the main clinical applications of calcium channel blockers?

Answer 20

Angina pectoris
Systemic hypertension
Supraventricular tachycardia
Post infarction protection.

Question 21

What type of drug is Verapamil and how does it work?

Answer 21

Verapamil is a non DHP calcium channel blocker that works by decreasing HR (SA automaticity)

and decreases AV conduction velocity increasing the PR interval.

Question 22

What effect does Verapamil have on the Effective refractory period?

Answer 22

Verapamil works to increase the effective refractory period and overall causes cardiac depression.

Question 23

Are calcium channel blockers good for arrhythmias?

Answer 23

these have no effect on sodium at all and thus are not for rhythm control at all.

Question 24

What are the two side effects of Verapamil?

Answer 24

Constipation and Exacerbate CHF.

Question 25

What are th two contraindications for Verapamil use?

Answer 25

WPW syndrome with Afib

Ventricular tachycardia.