beta blockers (selective and non-selective)

Question 1

MOA of all B-blockers (simplified)

Answer 1

Beta blockers/ beta adrenoreceptor antagonists block adrenergic (adrenaline) receptors and noradrenaline receptors leading to a reduction in heart rate and reduced contractility. Non- selective B-blockers work at multiple sites in the body e.g. B2 receptors on the lungs and B1 adrenoreceptor pace maker cells and heart muslce. whereas selective ones only work on B1 receptors

Question 2

MOA of B-blockers (longer version)

Answer 2

Beta blockers = beta-adrenoreceptor antagonists; antagonistically block adrenergic (adrenaline) receptors. the sympathetic neurons release the neurotransmitter adrenaline and this stimulates B1 adrenoreceptors on the heart pace maker cells and the heart muscle. This increases both the heart rate and contractility which in turn increases the work loads of the heart and so relating to angina, proabably increases the pain. Beta blockers tend to bind to and block B1 receptors on the heart and this reduces its responsiveness to sympathic activity. This lowers the hearts workload which leads to a reduction in heart rate and contractility. B blockers also reduce blood pressure by a mechansim that isnt fully understood. When BP is reduced in the aorta, this means that the heart has to beat less forcefully to push blood into the artieral system.

Question 3

contraindications of all B-blockers:

Answer 3

asthma, cardiogenic shock, hypotension, marked bradycardia, metabolic acidosis, severe peripheral arterial disease, sick sinus syndrome, uncontrolled heart failure.

Question 4

common side effects of all B blockers?

Answer 4

cold hands/ feet, worsening of reynauds syndrome, tiredness, insomnia, erectile dysfunction, altered lipid and glucose metabolism, nightmares/ vivid dreams.

Question 5

monitoring requirements: all b blockers?

Answer 5

monitor lung function in patients with history of obstructive airway disease.

Question 6

treatment cessation:

Answer 6

avoid abrupt withdrawal, especially in ischaemic heart disease. Sudden cessation of beta-blockder can cause rebound worsening of mycocardial ischaemia and therefore gradual reduction of dose is perferable when b- blockers are to be stopped.

Question 7

what is the name of the non-selective B-blocker?

Answer 7

propanaolol

Question 8

what are the names of the selective B-blockers?

Answer 8

Bisoprolol and Atenolol.