Anti-Arrhythmic Drugs

Question 1

Normal sinus rhythm phases

Answer 1

4: diastole (resting membrane potential)
0: rapid depolarisation (influx of Na)
1: early fast repolarisztion (inactivation of Na, entry of Cl, efflux of K)
2: plateau (balance of slow Ca & Na influx with K & Cl efflux)
3: repolarization (K efflux)

Question 2

Conductivity Meaning

Answer 2

Transfer of electrical impulses to next cell

Question 3

Automaticity Meaning

Answer 3

Cell generate electrical impulse without being stimulated

Question 4

Excitability Meaning

Answer 4

Cell change internal electrical balance to reach threshold

Question 5

Anti-Arrhythmic Drugs Classes

Answer 5

1: Na channel blockers (1A - Procainamide, 1B - Lidocaine, 1C - Flecainide)
2: Beta blockers (Metoprolol, Propranolol)
3: K channel blockers (Amiodarone)
4: Non-DHP Ca Channel Blockers (Verapamil, Diltiazem)
Adenosine

Question 6

Class 1A MOA

Answer 6

Lower rate of Phase 0 rise, conductivity, automaticity
Increased ERP & APD

Question 7

Class 1B MOA

Answer 7

Lower rate of Phase 0 rise, automaticity, APD
Shorten Phase 3 repolarization
No change in ERP

Question 8

Class 1C MOA

Answer 8

Lower rate of Phase 0 rise, automaticity, conductivity
Shortens Phase 3 repolarization
No/little effect on APD, ERP

Question 9

Class 1C Uses

Answer 9

Refractory ventricular tachycardias that tend to progress to VF

Question 10

Class 2 MOA

Answer 10

Lower Phase 4 depolarization, automaticity, HR & contractility
Prolong AV conduction
No change to APD, ERP

Question 11

Class 2 Uses

Answer 11

Tachycardia caused by sympathetic activation
AF
AV nodal reentrant tachycardia
Lower sudden arrhythmic death post-MI

Question 12

Class 3 MOA

Answer 12

Prolong Phase 3 repolarization
Increase ERP & APD

Question 13

Amiodarone MOA

Answer 13

Block lkr, lks, sodium channels, adrenergic receptor, calcium channels

Question 14

Amiodarone PK

Answer 14

F: 35-65%
M: by liver to desethylamiodarone (bioactive)
E1/2 life: 3-10 days (first 50%), several weeks (second 50%), after discontinuation - effects maintained for 1-3 months

Question 15

Amiodarone Uses

Answer 15

Maintain normal sinus rhythm in AF
Prevent reentrant ventricular tachycardia

Question 16

Amiodarone ADR

Answer 16

Symptomatic bradycardia
Heart block

Question 17

Class 4 MOA

Answer 17

Prolong Phase 4 depolarization
Lower AV node conductivity
Increase ERP & APD

Question 18

Verapamil Uses

Answer 18

Supraventricular tachycardia
Hypertension
Angina

Question 19

Verapamil ADR

Answer 19

Hypotension
Contraindicated in patients with preexisting depressed cardiac function

Question 20

Adenosine MOA

Answer 20

Suppress AV node conduction & increase AV nodal refractory period

Stimulate cardiac K channel, inhibit Ca current

Question 21

Adenosine PK, Uses

Answer 21

t1/2 < 10s
Use for supraventricular tachycardia

Question 22

Adenosine ADR

Answer 22

Flushing
Shortness of breath/chest burn
Induction of AV block/AF
Headache
Hypotension