Antiarrhythmic Drugs

Question 1

Class 1 antiarrhytmics block which channels?

Answer 1

Fast Na

Question 2

So class 1 antiarrhytmics block which PHASE of the myocyte AP?

Answer 2

Phase 0

Question 3

And if you block phase 0, what happens to the conduction velocity and refractory period in myocytes?

Answer 3

decrease CV and increase RP

Question 4

Which receptors do class 2 antiarrhytmics block?

Answer 4

Beta adrenergic receptors (B-blockers)

Question 5

Which receptors do class 3 antiarrhytmics block?

Answer 5

K channels

Question 6

Blocking K channels by class 3 antiarrhytmics does what to the AP?

Answer 6

Prolong it cuz it takes longer to repolarize the membrane

THIS ALSO INCREASES THE REFRACTORY PERIOD. BITCH.

Question 7

Which channels do class 4 antiarrhytmics block?

Answer 7

Ca++ channels

Question 8

Procainamide, Quinidine, and disopyramide belong to which class?

Answer 8

Class 1A

Question 9

Class 1A drugs (DQP) moderately block the Na channel, thus increasing the time it takes for the cell to reach what?

Answer 9

Threshold

Question 10

Class 1A drugs also block which channel, which prolongs the AP duration and increases the refractory period?

Answer 10

K+ channel

Question 11

Lidocaine and Mexiletine belong to which class of drugs?

Answer 11

Class 1B

Question 12

Why are class 1B antiarrhytmics called weak Na channel blockers, even though they bind to open and inactivated Na channel?

Answer 12

It has fast dissociation

Question 13

This weak blockage of the Na channel by 1B drugs does what to the AP duration and refractory period?

Answer 13

Make them shorter

Lidocaine + Mexiletine = “L”ittle “M”an = little AP

Question 14

For which conditions are 1B antiarrhytmics good for?

Answer 14

ischemia or any use-dependent problem

Question 15

What are the 2 class 1C antiarrhytmics?

Answer 15

Propafenone, Flecainide

“P”retty “F”reaky

Question 16

True or False: Class 1C drugs have no effect on AP duration.

Answer 16

True

Question 17

True or False: Class 1C drugs have no effect on the speed of phase 0.

Answer 17

FALSE. it decreases it a lot.

Question 18

True or False: Class 1C drugs have no effect on repolarization.

Answer 18

True!

Question 19

Since class 2 drugs inhibit the B1 receptors, what does it do to phase 4 depolarization at the nodal tissues?

Answer 19

Decrease it.

Question 20

Since B1 receptors normally increase Ca current into the cell, what happens to CV and RP with class 2 administration?

Answer 20

CV increases and RP decreases

Question 21

Amiodarone, dronedarone, sotalol, Dofetilide, and Ibutilide belong to which class of antiarrhytmics?

Answer 21

Class 3

Question 22

Since you prolong the RP and AP of the myocyte when u give a class 3 (cuz it blocks K channels), what arrhythmia are u putting the pt at risk for?

Answer 22

Torsade de Pontes

Question 23

True or False: class 3 drugs affect the slope of the phase 0 depolarization in myocytes.

Answer 23

False. They do nothing with it.

Like a wife 20 years into marriage.

Question 24

Verapamil and Diltiazem belong to which class of antiarrhytmics?

Answer 24

Class 4

WE TALKED ABOUT THIS LAST TEST KINDA YEAH. WOOOOOOOOOOOOOOOO

Question 25

Which channels do class 4 antiarrhytmics block?

Answer 25

Ca++

Question 26

True or False: class 4 antiarrhytmics do not affect Na-dependent tissues like purkinje fibers, atrial and ventricular muscle.

Answer 26

True

Question 27

So where do class 4 antiarrhytmics block Ca++ channels?

Answer 27

SA and AV nodes

Question 28

Since class 4 antiarrhytmics block the nodes and slow the conduction through them, which type of arrhythmia can they treat?

Answer 28

Re-entry

Question 29

This is the antiarrhytmic that opens G protein coupled K channels, which inhibit the node coductions, and also inhibits the Ca channel.

Answer 29

Adenosine