Beta-blockers Flashcards
What are some examples of B-blockers
-Bisoprolol, propanolol, atenolol
What are the indications for use
- HTN
- Arrthymias - AF + other tachyarrhythmia
- Angina
- Phaechromocytoma
- Anxiety
- Migraine prophylaxis
What is the mechanism of action of andrenergic receptors
- 2 types andrenergic receptors (stimulated by sympathetic NS) - alpha + beta
- A1 = vasoconstriction + bronchoconstriction
- A2 = reg andrenergic receptors
- B1 = increase cardiac contractility, HR + renin release
- B2 = Vasodilate, bronchodilate, increase HR, tremor, gluconeogenesis
- B3 = thermogenesis, lypolysis
What is the mechanism of action of different types of beta blockers and give examples + use
Non-selective B- antagonists
- equal B1 + B2 activity e.g. propanolol
- HTN + anxiety
B1 selective antagonists
- cardioselective e.g. atenolol, bisoprolol
- HTN + angina
Non-selective B- and A- antagonists
- Vasodilate + slow heart e.g. carvedilol
- Heart failure
What is the overall mechanism of action for beta-blockers
Block β-adrenergic receptors. Initially β-blockers ↓ BP by ↓ contractility and HR (β1)
Eventually CO returns to normal but vascular tone stays reduced
higher doses also block β2 in lungs+ vessels
- decrease renin production by kidneys = anti-HTN
- decrease conduction/AP initiation in heart = antiarrhythmic effect
- decrease HR + BP + CO
What are the side effects of B-blockers
Cold hands and worsens PVD (β2) Fatigue Bronchospasm and wheeze (β2) Bradycardia and hypotension Exacerbates psoriasis Overdose can cause heart block
What are the contraindications for b-blockers
Asthma and COPD Bradycardia Hypotension 2nd or 3rd degree heart block Severe peripheral artery disease Diabetes (masks hypoglycaemia – β2) CKD
What are the interactions of B-blockers
Ca Channel Blockers –> ↓ cardiac conduction too
Digoxin (also ↓HR)
Diuretics (also ↓BP)
Insulin (beta blockers mask hypoglycaemia)
