Antidysrhythmic Drugs

Question 1

How do we treat arrhythmias

Answer 1

Abnormal impulse generation
abnormal calculation

treatment: suppress abnormal impulses
inhibit abnormal conduction

Question 2

vaughan williams classification

Answer 2

system that is commonly used to classify antidysrhythmic drugs
based on the electrophysiologuc effect of particular drugs on the action potentia

Question 3

class 1 mechanism

Answer 3

membrane-stabilizing drugs

fast sodium channel blockers

Question 4

class 1 a action and indications

Answer 4

quinidine(long term)
procainamide(short term)
disopyramide

block sodium channels
delay repolarization
increases action potential duration
used for atrial fibrillation, premature atrial contractions, premature ventricular contractions, ventricular tachycardia, wolff-parkinson-white syndrome

Question 5

class 1a adverse drug reactions

Answer 5

QT prolongation leading to Torsades de points
Intracardiac vagal block
GI disturbances
Cinchonism
SLE and agranulocytosis

Question 6

Class1b: action and indication

Answer 6

• phenytoin, lidocaine
• block sodium channels
• accelerate repolarization
• increase or decrease action potential duration
• used for ventricular dysrhythmias only
• premature ventricular contractions, ventricular tachycardia, ventricular fibrillation

Question 7

Class 1b Adverse Effects

Answer 7

drowsiness
Slurred speech
parasthesias
agitation
confusion
convulsions

Question 8

class 1c action and indications

Answer 8

flecainide, propafenone

• block sodium channels
• little effect on repolarization
• used for severe ventricular dysrhythmias may be used in atrial fibrillation/flutter, wolff-parkinson-white syndrome, supraventricular tachycardia dysrhythmias

Question 9

Class 1c adverse effects

Answer 9

• negative ionotropic effect, thus can aggravate HF
• dizziness
• blurred vision
• headache
• nause
• aggravate preexisting arrhythmias

Question 10

Class 2 beta blockers action and indications

Answer 10

atenolol, esmolol, metaprolol, propranolol

• reduce or block sympathetic nervous system stimulation, thus reducing transmission of impulses in the hearts conduction system
• depress phase 4 depolarization
• general myocardial depressants for both supraventricular and ventricular dysrhythmias
• also used as antianginal and antihypertensive drugs

Question 11

class 2 beta blockers adverse effects

Answer 11

hypotension
impaired lipid metabolism
bronchospasm

Question 12

class 3: action and indications

Answer 12

amiodarone, sotalol, ibulitide
potassium channel blockers
increase APD
prolong repolarization in phase 3
used for dysrhythmias that are difficult to treat
-life-threatening ventricular tachycardias or fibrillation, atrial fibrillaion or flutter-resistnt to other drugs
-sustained ventricular tachycardia

Question 13

class 4 action and indications

Answer 13

verapamil, diltiazem
calcium channel blockers
-inhibit slow-channel pathways
Depress phase 4 depolarization
reduce AV node conduction
used for paroxysmal supraventricular tachycardia, rate control for atrial fibrillation and flutter

Question 14

class 5

Answer 14

digoxin, adenosine

-have properties of several classes and are not placed into one particular class

Question 15

adenosine

Answer 15

-slows conduction through the AV node
-used to convert paroxysmal supraventricular tachycardia to sinus rhythm
-very short half life
only administered as fast IV push
may cause asystole for a few secons
other adverse effects are minimal