Beta Adrenoreceptor Antagonists Flashcards
For each condition listed, give the relevant complications:
1) Aneurysms (Charcot-Bouchard/ Berry)
2) LVH
3) Arterial fibrinoid necrosis in malignant HTN
4) Atheroma
1) Intracerebral/ subarachnoid haemorrhage
2) IHD, heart failure, arrhythmias and sudden death.
3) Renal failure
4) thromboembolic strokes, IHD, aortic aneurysm, CKD, peripheral vascular disease (intermittent claudication).
Name 3 important actions of Beta blockers for reducing BP.
- reduction of HR and myocardial activity causing decreased CO.
- antagonism at renal JGA beta-1 adrenoreceptors which reduces renin secretion.
- block pre-synaptic Beta- adrenoreceptors in sympathetic neurons that supply arteriolar resistance vessels. This reduces release of NA. This attenuated reflex arterial vasoconstriction.
Name 3 beta-adrenoreceptor antagonists.
State which of these drugs has a hybrid action, and state what this action is thought to be.
Atenolol, Bisoprolol, Nebivolol, Propranolol, Metoprolol.
Nebivolol has a hybrid action, and this action is thought to be peripheral arterial vasodilation.
Name the 5 common clinical indications for the use of beta-blockers.
State the reasons that they might be indicated.
1) IHD - first line option. Improve symptoms and prognosis for angina and ACS.
2) Chronic heart failure - first line option to improve prognosis.
3) AF - first line option to reduce ventricular rate.
3a) Paroxysmal AF - to maintain sinus rhythm.
4) SVT - first line option to restore sinus rhythm. In patients with no circulatory compromise.
5) HTN - not indicated for initial therapy. Used when other drugs are insufficient or inappropriate.
1) Where are beta1 adrenoreceptors located?
2) Where are beta2 adrenoreceptors located?
1) mainly in the heart
2) smooth muscle of blood vessels and airways.
1) What is the action of beta blockers via beta1 receptors?
2) What is the result of blocking beta1 receptors?
3) How do beta blockers improve heart failure prognosis?
4) How do beta blockers slow ventricular rate in AF?
1) They reduce force of contraction and speed of conduction in the heart.
2) Relieves myocardial ischaemia by reducing cardiac work and oxygen demand. Also increases myocardial perfusion.
3) Protect the heart from effects of chronic sympathetic stimulation.
4) By prolonging the refractory period of the AVN.
1) Why can beta blockers be used for SVT?
2) Why can beta blockers be used to reduce renin secretion?
1) SVT can involve a self perpetuating re-entry circuit, involving the AVN. Beta blockers can break this re-entry circuit and restore sinus rhythm.
2) Because renin secret is from the kidney is mediated by Beta1 receptors.
Give 5 important adverse effects of beta blockers.
1) Fatigue
2) Cold extremities
3) Headache
4) GIT disturbance
5) Sleep disturbance and nightmares
6) Impotence in men.
1) Name 3 beta1 selective beta blockers.
2) Name 2 non-selective beta blockers.
1) Atenolol, Bisoprolol, Metoprolol.
2) Propranolol, Carvedilol.
1) Why are beta blockers contraindicated in patients with asthma?
2) What is the recommendation for using beta blockers in patients with COPD?
1) They can cause life threatening bronchospasm, due to blockade of beta 2 receptors.
2) Beta blockers are considered safe to use in COPD, but it is recommended to use a selective one.
1) In heart failure, why should beta blockers be started at a low dose which is gradually increased?
2) Aside from asthma, name 2 other conditions that use of beta blockers is contraindicated in.
3) In which condition do beta blockers require significant dose reduction?
1) Because they may impair cardiac function.
2) Haemodynamic instability and heart block.
3) hepatic failure.
1) What drugs must beta blockers not be used in conjunction with?
2) Why is this?
1) Non-dihydropyridjne calcium channel blockers (Verapamil and Diltiazem).
2) Because this combination can cause bradycardia, heart failure and asystole.
