B4.017 - Anti-arrhythmic Drugs

Question 1

what are the extracardiac effects of amiodarone

Answer 1

peripheral vasodilation especially after IV administration

Question 2

what is lidocaine used for

Answer 2

ventricular arrhythmias most effectively associated with MI ischemia or digoxin toxicity

Question 3

which drug is used for acute tachicardias during surgery

Answer 3

esmolol

Question 4

harmful effects of beta blockers

Answer 4

negative inotropy may worsen HF in patients with acute myocardial infarction or decompensated heart failure

Question 5

how is lidocaine given and why

Answer 5

IV, high first pass metabolism

Question 6

what is Procainamide used for and why

Answer 6

it increases refractory period so can help treat atrial and ventricular tachycardia

Question 7

extracardiac effects of quinidine

Answer 7

blocks alpha adrenergic receptors to cause vasodilation which can lead to marked hypotension and reflex tachycardia

also has antimuscarinic effects

Question 8

what is disopyramide approved in US to treat

Answer 8

ventricular arrhythmias

not used often because of antimuscarinic effect

Question 9

what is the least cardiotoxic antiarrythmic drug

Answer 9

lidocaine

Question 10

does procainamide elevate digoxin levels?

Answer 10

no

Question 11

how do class 1 sodium channel blockers work

Answer 11

decrease HR by elevating threshold for excitation and decreasing phase 4 depolarization in SA node

Question 12

Lidocaine is rarely effective for what

Answer 12

normally polarized tissues like atrial flutter or fibrillation

Question 13

which drug class prolongs action potential duration in addition to being a sodium channel blocker and what can that cause

Answer 13

Class 1A

Procainamide, Quinidine, Disopyramide

QT prolongation

Question 14

Class 1C drugs

Answer 14

Flecainide, propafenone, moricizine

Question 15

which drug releases NO from endothelial cells

Answer 15

amiodarone

Question 16

cardiac effects of amiodarone

Answer 16

prolongs AP duration by blocking K channels

decreases rate of firing in pacemaker cells by blocking inactivated Na channels

blocks alpha and beta adrenergic receptors and calcium channels and thus inhibits AV node conduction to produce bradycardia

Question 17

what is the half life of amiodarone

Answer 17

short 3-10 days

slower - several weeks, toxicity long after it is discontinued

Question 18

what is sotalol used for

Answer 18

life threatening ventricular arrhythmias

maintainging sinus rhythm in a fib

treatment of supraventricular and ventricular arrhythmias in pediatrics

Question 19

what are the 2 most frequently used beta blockers and what are they used for

Answer 19

propranolol and atenolol

rate control

to treat supraventricular and ventricular arrhythmias caused by sympathetic stimulation or to prevent ventricular fibrilation

Question 20

what can procainamide cause due to a prolonged QT interval

Answer 20

life threatening arrythmias

Question 21

what are toxicities of quinidine

Answer 21

precipitates digoxin

thrombocytopenia

syncope due to torsade de pointe

chinchonism (headahce, dizziness, tinnitus)

Question 22

beneficial effects of beta blockers

Answer 22

diminished sympathetic activation of heart and blood vessels and thus diminished workload

Question 23

which drug can cause SA and AV node depression directly

Answer 23

Procainamide

Question 24

what does moricizine do

Answer 24

potent sodium channel blocker that does not prolong APD

Question 25

what are the class 1A drugs

Answer 25

Procainimide, Quinidine, Disopryramide

Question 26

what drug has a very narrow therapeutic window

Answer 26

digoxin

Question 27

what is teh difference between mexiletine and lidocaine

Answer 27

lidocaine has to be given IV because of first pass system Mexiletine can be given orally Mexiletine can also be used for relief of chornic pain especially in diabetic neuroathy and nerve injury

Question 28

what are amiodarone toxicities

Answer 28

asymptomatic bradycardia and AV block pulmonary fibrosis abnormal liver function and hepatitis grayish blue skin corneal microdeposits thyroid function needs to be evaluated before treatment blocks T4-T3 hypothyroidism or hyperthyroidism

Question 29

how is amiodarone given and why

Answer 29

orally or IV to maintain normal sinus rhythm in patietns with a fib or prevent recurrent ventricular tahcycardia

Question 30

what will enhance toxicity of digoxin

Answer 30

hypokalemia

Question 31

what effect do Class 1B drugs have on APD

Answer 31

shortened APD

Question 32

what is the main therapeutic use of adenosine

Answer 32

IV injection to convert paroxysmal supraventricular tachycardia to sinus rhythm, very short half life

Question 33

what drug type causes this

Answer 33

Class 1A Procainamide, quinidine, disopyramide moderate Na+ channel block; prolong APD

Question 34

what effect do class 1C drugs have on APD

Answer 34

minimal effect on APD

Question 35

magnesium is used for what

Answer 35

to prevent torsade de pointes

Question 36

what drug has a metallic taste

Answer 36

propafenoe

Question 37

what does digoxin do to heart rate

Answer 37

stimulates vagus nerve and decreases heart rate can be used in atrial fibrillation to decrease the rate

Question 38

why is digoxin more toxic in hypokalemic patients

Answer 38

K and digoxin compete for bidning to Na/K ATPase so if theres less potassium to compete its effects will be too strong

Question 39

what does adenosine do

Answer 39

opens inward rectifier K+ channels leading to hyperpolarization and inhibits L type calcium channels to inhibit calcium entry and conduction velocity in AV node

Question 40

digoxin toxicities

Answer 40

GI - nauseal vomiting, diarrhea, abdominal discomfort cardiac - can lead to almost all arrhythmias

Question 41

what is flecainide very effective in suppressing

Answer 41

premature ventricular contractions

Question 42

what are oral class IV antiarrhythmics used for treatment of

Answer 42

supraventricular arrhythmias and for rate control in a fib

Question 43

what drug class causes this

Answer 43

Class 1B Lidocaine, Mexiletine Shorten APD

Question 44

what does quinidine precipitate

Answer 44

digoxin toxicity

Question 45

what are the extracardiac effects of procainamide

Answer 45

ganglion blocking activity which reduces peripheral resistance and can lead to hypotension

Question 46

which effect do class 1A drugs have on APD

Answer 46

prolonged APD

Question 47

cadiotoxic effects of procainamide

Answer 47

QT prolongation inducing torsades de pointes

Question 48

class 1B drugs

Answer 48

Lidocaine, Mexiletine

Question 50

does flecainanide have antimuscarinic effects

Answer 50

no

Question 51

what is flecainide used to treat

Answer 51

supraventricular arrhythmias

Question 52

what is the similarity of class 1A antiarrhythmics

Answer 52

all block Na andK channels and induce torsade de pointes

Question 53

what does Flecainide do

Answer 53

blocks Na+ and K+ channels with no QT prologation

Question 54

procainamide long term adverse extra cardiac effects

Answer 54

reversible lupus like syndrome (rash, arthralgia, arthritis, pericarditis)

Question 55

what are the anti arrhythmic drugs that are not part of the 4 classes

Answer 55

Adenosine Digoxin Magnesium

Question 56

therapeutic use of procainamide

Answer 56

most atrial and ventricular arrhythmias short hlaf life so less useful for long term oral treatment

Question 57

what is dronedarone

Answer 57

structural analogue of amiodarone but no iodines

Question 58

what does digoxin do

Answer 58

potent and selective inhibitor of Na/K ATPase --\> increased intracellular calcium concentration --\> positive inotrope

Question 59

what drug has modest muscarinic effects

Answer 59

quinidine

Question 60

how are all class 1 C antiarrhythmics administered

Answer 60

orally

Question 61

what is sotalol

Answer 61

class 3 antiarrhythmic used as beta blocker and potassium channel blocker

Question 62

how is amiodarone metabolized

Answer 62

CYP3A4 --\> drug drug interactions

Question 63

what drug class causes this

Answer 63

Drug class 1C Minimal effect on APD Flecainide, propafenone, moricizine

Question 64

what drug has a black box warning and what is it for

Answer 64

dronedarone amiodarone analogue increased risk of death, stroke and heart failure in patients with decompensated heart failure or a fib

Question 65

what are toxicities of disopyramide

Answer 65

more antimuscarinic effects than quinidine Atropine like activity: Urinary retention Dry mouth, blurred vission, constipation worsening glaucoma

Question 66

what are the 4 classes of anti arrhythmic drugs

Answer 66

Class 1 - sodium channel blockers Class 2 - beta blockers Class 3 - potassium channel blockers Class 4 - calcium channel blockers

Question 67

what do verapamil and dilitiazem

Answer 67

block L type Ca channels in myocardium and vascular smooth muscle decreases contractility reduces SA node automaticity slow AV node conduction

Question 68

how does adenosine inhibit pacemaker current

Answer 68

decreases heart rate

Question 69

which drug is withdrawn from US market

Answer 69

moricizine

Question 70

what are common side effects of dofetilide adn ibutilide

Answer 70

prolonged QT and torsade de pointes

Question 71

compare and contrast the antimuscarinic, lupus like syndrome, plasma digoxin and alpha adrenergic block of the class 1A drugs

Answer 71

Question 72

propafenone blocks what well and what weakly

Answer 72

blocks Na well, beta blocking activity weakly because its a propranolol analogue