CVS drugs - Anti-arrhythmics, diuretics and anti-fat

Question 1

What four types of drugs are in the vaughn williams classification?

Answer 1

Na+ channel blockers
B-blockers
K+ channel blockers
Ca2+ channel blockers

Question 2

What are the three mechanisms of action of Na+ channel blockers?

Answer 2

Decrease conduction velocity
Increase depolarisation threshold
Decrease automacity

Question 3

Why would you use fleicanide?

Answer 3

Atrial Fib

Question 4

Give two CIs for Flecainide

Answer 4

Heart failure (make it worse at beating)
History of MI (can worsen arrhythmias)

Question 5

What is the mechanism of action of felcainide?

Answer 5

Block fast, inward Na+ channels

Question 6

Give three ADRs for flecanide

Answer 6

 Dizziness, visual disturbances, arrhythmias

Question 7

What could effect metabolism of flecainide?

Answer 7

GO-DEVICES

Grapefruit juice, omeprazole

Question 8

When would you use lidocaine?

Answer 8

Ventricular arrhytmia following MI

Question 9

What is the mech of action for lidocaine?

Answer 9

Blocks fast, inward Na+ channels

Question 10

Give three adverse drug reactions for lidocaine

Answer 10

Hypotension, bradycardia (Negative inotrope)
Nystagmus (brain)
Seizures (Brain)

Question 11

What do beta blockers do to ventricular action potential?

Answer 11

Shift to right

Question 12

Give four indications for beta blockers

Answer 12

Angina
Post myocardial infarctioin
Hypertension
Arrhytmias

Question 13

How do beta blockers work as anti-arrhytmics?

Answer 13

 Antagonise β-adrenoreceptors. β1-receptors are found in the heart, when they are activated they cause increased Chronotropy and Inotropy.
 Inhibit renin release

Question 14

Give some of the 6 ADRs of beta blockers?

Answer 14

Bronchospasm
Fatigue and insomnia
Hypotension 
Bradycardia 
Decreased glucose tolerance - Don't feel adrenaline from hypoglycaemia due to B blockers

Question 15

Give two significant DDIs of beta blockers

Answer 15

 Prevents Salbutamol working (β2-adrenoagonist)

 Verapamil – Both have –‘ve inotropic action

Question 16

How do potassium channel blockers work?

Answer 16

Block potassium channels which -
Increases absolute refractory period
Increased AP duration
Suprress re-entry circuits by closing excitable gap

Question 17

What is torsades de pointes

Answer 17

Ventricular tachycardia which can result in death

Question 18

Why must you be careful using amiodarone in a patient on warfarin?

Answer 18

Amiodarione inhibits cyp450 which requires dose reduction of everything else which undergoes liver metabolism

Question 19

How do calcium channel blockers work?

Answer 19

Decrease slop of pacemaker aciton potential at SA node and AV node - Dependent on Ca2+ influx and efflux!
This increaes refractory period, chronotrophy and inotropy

Question 20

When should calcium channel blockers not be used?

Answer 20

Heart failure
Bradycardia
AV node block

Question 21

What are four ADRs of calcium channel blockers?

Answer 21

Hypotension
Bradycardia
Heart failure
Heart block

Question 22

What does adenosine effect?

Answer 22

AV node blocker

Question 23

When is digoxin used?

Answer 23

Atrial fib

Heart failure

Question 24

Give the mechanism of action and effects of digoxin

Answer 24

o	Inhibits Na/K-ATPase
o	Direct Cardiac Effects
 Increased Inotrope – Used in heart failure, no mortality benefit
o	CNS Effects
 Decreased Sympathetic outflow
 Increased Parasympathetic outflow
	Sensitises baroreceptor reflex
o	Combined Effects
	 Automaticity of SAN and AVN
	 AVN refractory period
	 Conduction velocity of AVN

Question 25

Why is digoxin dangerous?

Answer 25

Narrow therapeutic index

Question 26

What three things happen in digoxin toxicity?

Answer 26

bradycardia, AVN block, atrial tachycardia

Question 27

What amplifies toxicity of digoxin?

Answer 27

Hypokalaemia

Question 28

What increases digoxin levels in blood?

Answer 28

Quinidine, amiodarone, verapamil, spironolactone

Question 29

What increases effect of digoxin in blood already?

Answer 29

Beta blockers (both decrease AV node conduction)
Verapamil (both decrease cardiac contractility)
Loop and thiazide diuretic (both cause hypokalaemia)

Question 30

How must digoxin be given?

Answer 30

Two separate doses to minimise toxicity risk