Beta-blockers (selective and non-selective) Flashcards
Name examples of selective and non-selective beta-blockers.
selective - bisoprolol, atenolol
non-selective - propranolol
What are the general indications of beta-blockers?
hypertension, angina, myocardial infarction and prophylaxis of, arrhythmias, heart failure, thyrotoxicosis, anxiety, prophylaxis of migraine.
What are additional indications of propranolol?
thyrotoxic crisis, prophylaxis of variceal bleeding in portal hypertension, phaechromocytoma with an alpha blocker, hypertrophic cardiomyopathy, anxiety tachycardia, essential tremor.
What are the contraindications of beta-blockers?
second/third-degree heart block, unstable heart failure, asthma, cardiogenic shock, hypotension, marked bradycardia, metabolic acidosis, phaeochromocytoma (without an alpha blocker), Prinzmetal’s angina, severe peripheral arterial disease, sick sinus syndrome.
What is the mechanism of action of beta-blockers?
Beta-blockers/beta-adrenoceptor blockers block the beta-adrenoceptors in the heart, peripheral vasculature, bronchi, pancreas and liver, and therefore inhibit the release of adrenaline and noradrenaline which leads to a reduction in heart rate and reduced contractility.
Non-selective beta blockers work at multiple sites within the body, selective beta blockers tend to work on the cardiac muscle only.
What is the theorised mechanism of action of beta-blockers in hypertension?
The mode of action in hypertension is not fully understood, but they reduce cardiac output, alter baroreceptor reflex sensitivity, block peripheral adrenoceptors and some depress plasma renin secretion which all influence blood pressure.
What is the mechanism of action of beta-blockers in angina?
In angina, as beta-blockers reduce cardiac work they improve exercise tolerance and relieve symptoms of angina.
What is the mechanism of action of beta-blockers in arrhythmias?
They act as anti-arrhythmic drugs by reducing the effects of the sympathetic nervous system on automaticity and conductivity within the heart.
How do beta-blockers help in heart failure?
They may be of benefit in heart failure by blocking sympathetic activity.
What are the common/very common unwanted side effects of beta-blockers?
cold hands/feet, worsening of Reynaud’s syndrome, nightmares/vivid dreams (lipid soluble beta-blockers), tiredness, insomnia, erectile dysfunction, altered lipid and glucose metabolism.
What are the monitoring requirements of beta-blockers?
Monitor lung function in patient with history of obstructive airway disease.
What is the treatment cessation protocol for beta-blockers?
Avoid abrupt withdrawal, especially in ischaemic heart disease, as sudden cessation can cause rebound worsening of myocardial ischaemia.
