Antiarrythmic Drugs

Question 1

Class I mechanism of action
Class II mech of action
Class III mech of action
Class IV mech of action

Answer 1

I: Na+ channel blocker
II: B adrenoreceptor blocker
III: K+ channel blocker
IV: Ca+ channel blocker

Question 2

IA:
IB:
IC:
II:
III:
IV:

Answer 2

Slows phase 0 depo in ventricular mf
Shortens phase 3 rep in ventri
Slows phase 0 dep
Inhibut phase 4 in SA and AV
Prolong phase 3 repolarization
Inhibit action potential in SA and AV

Question 3

T or F
Most anti arrythmic drugs are pro arrythmic

Answer 3

True
Especially class I

Question 4

Class IA names:
1-
2-
3-

Answer 4

Quinidine
Procainamide
Disopyramide

Question 5

Class IA mode of action

Answer 5

Slow phase 0 and prolong AP and slow conduction
Prolong repolarization by blocking some K channels
Increase ERP

Question 6

T or F
Quinidine doesn’t have alpha adrenergic blocking effect and anticholinergic

Answer 6

False
It has

Question 7

Therapeutic uses of class IA

Answer 7

Atrial and ventriculat tachy

Question 8

Pharmakokinetics of class IA

Answer 8

Rapidly absorbed after oral adm
Extensive metabolism by CYP3A4

Question 9

Adverse effects:
1-
2-
3-
4-

Answer 9

Has atropine
Tinnitus headache blurred vision
Development of some arrythmias
SA and AV block or asystole

Question 10

Class IB
Mode of action:
Names
1-
2-
3-

Answer 10

Shorten phase 3 repolarization
Decrease the duration of AP
1-lidocaine
2-mexiletine
3-tocainide

Question 11

Lidocaine:
Therapeutic uses
Phramcokinetics
Adverse

Answer 11

Ventricular arrythmias
Lidocaine given IV (because of extensive 1st pass effect)
CNS toxicity

Question 12

Class IC
Mode of action:
Names:
1-
2-

Answer 12

Markedly slow phase 0 (conduction)
Have little effect on duration of the AP
1-flecainide
2-propafenone

Question 13

Flecainide:
Therapeutic uses:
Adverse effects:1—–2—–
Contraindications 1——-2—–

Answer 13

Ventricular arrythmias
Adverse: visual disturbances-dizziness
Contra: hypersensitivity-2nd and 3rd degree AV block

Question 14

B blockers:
Mode of action:
Names:
1-
2-
3-

Answer 14

Diminish phase 4 depo
Depress automaticity
Prolonging AV conduction
Decr HR and contractility
Esmolol
Metoprolol
Propranolol

Question 15

B blocker
Uses:

Answer 15

Tachy arrythmias
Atrial flutter and fib and AV nodal reentrat tachy

Question 16

K+ blockers
Names:
Mode of action

Answer 16

Amiodarone
Sotalol
Dofetilide
Prolongation of phase 3 without altering phase 0
Prolong duration of AP and ERP

Question 17

Amiodarone:
Uses:

Answer 17

Serious ventricular arrythmias
Taken up by tissues especially adipose

Question 18

T or F
Amiodarone antiarrythmic effects compromise class I II III and IV

Answer 18

T

Question 19

Mechanism of action:
1-
2-
3-

Answer 19

1-Prolongation of AP and refractoriness K+ channel blocker + partially Na+ blocker effect type Ia
2- slows cardiac automaticity and AV conduction as Ca2+ channel blocker type verapamil
3- weak b-adrenergic blocker (prolongation of AP)

Question 20

Contraindication:
Therapeutic uses:

Answer 20

-pre-existing depressed heart function because of their negative ionotropic
-recurrent and refractory ventricular and supra-ventricular arrythmias

Question 21

Adverse effects of amiodarone:
1-
2-
3-
4-
5-
6-

Answer 21

Gray-blue skin discoloration and photo-dermatitis
Corneal microdeposits
Pulmonary fibrosis
Hypo or hyperthyrodism
Hepatic impairment
Neurological effects

Question 22

T or F
The most used antiarrythmic drug is lidocaine

Answer 22

False
Amiodarone

Question 23

Ca2+ blockers
Mode of action
Names:
1-
2-

Answer 23

Decrease inward Ca2+ so it decrease phase 4 spintaneous dep (SA)
Slow conduction in Ca2+ current dep like AV
1-verapamil
2-diltiazem

Question 24

Uses of class IV

Answer 24

Effective in treating arrythmias that must traverse Ca2+ dependent cardiac tissue
Reentrant supraventricular tachycardia and in reducing the ventricular rate in atrial flutter and fibrillation

Question 25

T or F
Verapamil and diltiazem are more effective in ventricular arrythmias than atrial

Answer 25

False
In atrial more