Adrenergic antagonists: Beta blockers

Question 1

What are adrenergic antagonists ?

Answer 1

These are medications that inhibit the post synaptic alpha and beta adrenergic receptors from being stimulated by catecholamines epinephrine and nor-epinephrine.

Question 2

What are the subtypes of beta adrenergic receptors ?

Answer 2

Beta 01 and 02.

Question 3

Where are beat 01 adrenergic receptors located ?

Answer 3

*In the heart responsible for increasing HR and contractility.
* In the juxta-glomerular cells responsible for increasing Rennin secretion.

Question 4

What is the action of Rennin ?

Answer 4

It is part of the Rennin-angiotestin-aldosterone system which increase the BP by retaining sodium and water in the body.

Question 5

What is the action of beta 2 adrenergic receptors and their location ?

Answer 5

*These receptors stimulate vasodilation and increase blood flow to the muscles, and brain.
*It also cause bronchodilation in the lungs.
* In the GI system it decrease motility and slow digestion.
* In the eyes it acts on the ciliary body to promote the secretion of aqueous humour.
* In the liver they promote gluconeogenesis and in the pancreatic islets they stimulate alpha cells to release glucagone.

Question 6

What is the role of beta two receptors on triglycerides ?

Answer 6

It activates the enzyme lipoprotein lipase to breakdown triglyceride to fatty acid and cholesterol.

Question 7

What are the first generation beta blockers ?

Answer 7

They are non selective beta blockers
Propranolol
Nadolol
Sotalol
Pindolol
Timolol

Question 8

Pindolol is a __________of beta receptors

Answer 8

partial agonist

Question 9

What are the physiological effects of first generation beta blockers ?

Answer 9

• Reduction in HR and cardiac contractility.
• Reduction in cardiac O2 and energy demand as well as drop in BP.
• In the kidney it inhibits the Rennin angiotestin aldosterone system leading to reduced BP.
  *

Question 10

Which is the only one beta blocker that can cause Blood brain barrier ?

Answer 10

the first generation beta blocker Propranolol.

Question 11

What are the undesired effects of non selective beta blockers?

Answer 11

• Bronchoconstriction.
• Increased GI motility
• Drop in intra-occular pressure due to reduced aqueous fluid production.
• Hypoglycemia due to hepatic and pancreatic beta receptor inhibition.
• Increase in triglycerides due to inhbition of lipoprotein lipase.

Question 12

What are the clinical indications of first generation beta blockers?

Answer 12

• HTN, CAD, and CHF.
• Thyroid storm related severe tachycardia.
• Anxiety and migraine prophylaxis
• To reduce IOP in glaucoma.

Question 13

What are the side effects of first generation non selective Beta blockers ?

Answer 13

• Rebound tachycardia
• Hypotension and bradycardia
• Braddy arrhythmia
• fatigue, dizziness, depression, insomnia and nightmares.

Question 14

What are the cardio selective beta 01 blockers ?

Answer 14

• Atenolol, Metoprolol
• Bisoprolol, Esmolol
• Acebutolol

Question 15

What is the advantage of beta 01 selective blockers ?

Answer 15

They only act on the beta 01 receptors of the heart and juxtaglomerular cells of the kidney. Hence they are safer drugs for rate, contraction and BP control with minimal side effects. They are also safe choices in people with Asthma and COPD and are the preferred beta blockers for those with diabetes.

Question 16

What are the third generation beta blockers ?

Answer 16

Labetalol and Carvedelol. they have alpha 01 agonism also in addition to beta 1 agonism. They are therefore, useful in peripheral arterial disease with HTN.

Question 17

Labetalol is the prefered beta blocker for treating HTN in _______.

Answer 17

Pregnancy.