Drug Class: Beta Blockers (class 2 Anti-arrhythmics)

Question 1

Example of Beta 1 blockers

Answer 1

BISOPROLOL- first line for AFib
CARVEDIOL
ATENOLOL
METOPROLOL

Question 2

Example of beta 1+2 blockers

Answer 2

PROPANOLOL

Question 3

Mode of action of Beta 1 receptor blockers

Answer 3

Beta 1 receptors found in SA, AV nodes and myocytes
• Slows SA discharge and AV conduction-> prolongs phase 4 repolarisation
• Reduces excitability in non-nodal cardiac tissue-> ↓ ectopic firing
• Slow HR and conduction
• Increases diastolic filling time
• Reduces BP
• Decreases contractility (phase 2- Ca2+ entry)
• Reduce renin secretion

Question 4

Mode of action of beta 2 receptor blockers

Answer 4

Beta 2 receptors found in smooth muscle of airways, peripheral vasculature, and skeletal muscle

Question 5

Side effects of beta blockers

Answer 5

• Tiredness/fatigue
• Lethargy
• Impotence
• Bradycardia
• Bronchospasm
• Rebound (taper off dose over 1-2 weeks)

Question 6

Drug-drug interactions of beta blockers

Answer 6

• Hypotension when w/ hypotensive agents
• Bradycardia w/ verapamil or diltiazem
• Heart failure w/ verapamil or diltiazem
• Exaggerate/ mask insulin induced hypoglycaemia

Question 7

Contraindications of beta blockers

Answer 7

• Use with caution in HF- patients dependent on sympathetic drive
• Do NOT use in Acute HF if fluid overload
• Do not use in asthma (no beta blocker is fully selective)
• Peripheral vascular disease
• Raynaud’s syndrome
• Existing bradycardia/ heart block