Antiarrythmic Drugs

Question 1

What is the general mechanism by which Class I antiarrythmic work?

Answer 1

These are broken into 3 classes.
All three of which involve sodium channels specifically in the Conducting tissues of the heart.

Act to increase the ERP/APD

Question 2

What are the three class I antiarrythmic drugs?

Answer 2

Quinidine
Procainamide
Disopyramide

Question 3

What is the channel specificity for the Class Ia agents in general?

Answer 3

These bind to Sodium channels in a state dependent manner binding only the active and inactive forms.

Question 4

What is the function of the drug Quinidine?

Answer 4

Class 1a antiarrythmic drug.
Binds to open Na+ channels decreasing Vmax of phase O.

Also blocks the potassium channels increasing the APD.

Quinidine also has alpha and muscarinic effects. This means BP will be lowered and HR will be increased.

Question 5

What are the side effects of quinidine?

Answer 5

Can cause cinchism
Hypotension
As well as proarythmic (Muscarinic block = ^HR)

Question 6

What makes procainamide different than quinidine?

Answer 6

Does not have the alpha effects or the muscarinic effects.

Question 7

What are the indications for procainamide/

Answer 7

Reentrant SVT
Aib
A flutter with WPW.

Question 8

What drug makes for good use in digitalis and Mi induced arrhythmia?

Answer 8

Class 1b antiarrhythmic drugs

Lidocaine and Mexiletine

Question 9

What type of tissue is lidocaine best indicated for?

Answer 9

ischemic heart tissue best post MI.

Question 10

What is the MoA for the drug flecainide?

Answer 10

Slows intravascular intraventricular conduction.

Question 11

What is Flecainide indicated for?

Answer 11

Indicated for ischemic heart disease.

Question 12

What are the class II agents?

Answer 12

These are beta blockers.

Question 13

How do the beta blockers work?

Answer 13

These work by decreasing cAMP and calcium currents decreasing SA automaticity (phase 4), AV nodal conduction and ventricular contractility.

Question 14

What class of drugs are the only antiarrhythmic drugs found to be clearly effective in preventing sudden cardiac death in patients with prior MI?

Answer 14

Class II antiarryhthmics Beta Blockers!

Question 15

Why is Esmolol a good Beta blocker to know for the exam?

Answer 15

It has a very short half life for IV use.

Deffinetly useful when short termed beta blockade is desired.

Question 16

What are the side effects of Class II agent Beta blockers?

Answer 16

Impotence
Exacerbation of COPD and asthma
Bradycardia, AV block etc
Can mask hypoglycemia etc.

Question 17

What is the use of the beta blocker carvedilol and Labetalol?

Answer 17

These beta blockers are excellent for patients with pheochromocytoma or cocaine toxicity as they block both Alpha and Beta receptors.