Alpha Blockers

Question 1

What are Alpha Blockers?

Answer 1

Drugs that block α adrenoceptors profoundly affect blood pressure. Because normal sympathetic control of the vasculature occurs in large part through agonist actions on α-adrenergic receptors, blockade of these
receptors reduces the sympathetic tone of the blood vessels, resulting in decreased peripheral vascular resistance.

Question 2

What do Phenoxybenzamine and Phentolamine do?

Answer 2

These are the NON-Selective alpha blockers but their use is limited due to the excessive tachycardia

Question 3

What is the contradictory side effect of phenoxybenzamine and phentolamine?

Answer 3

Cardiovascular stimulation opposes the vasodilatory effect intended.

Question 4

What are some of the uses of phenoxybenzamine?

Answer 4

Rx of sympathetic excess 2° to pheochromocytoma, Raynaud’s phenomenon, frostbite, and acrocyanosis

Question 5

What is a consequence of the decreased sympathetic induced by alpha blockers.

Answer 5

This induces a reflex tachycardia resulting from the lowered blood pressure. The magnitude of the response depends on the sympathetic tone of the individual when the agent is given.Effects are more profound in an individual who is standing and less in a
person who is supine.

Question 6

What drug is used to treat symptoms of BPH?

Answer 6

Alfuzosin [Uroxatral] is more specific for alpha-1a receptors than other alpha1-receptor antagonists.

Question 7

How does Alfuzosin work in treating BPH?

Answer 7

Blockade of alpha-1a in bladder neck and prostate can improve urine flow rate and reducing symptoms of benign prostatic hypertrophy (BPH)

Question 8

What are some of the uses of phentolamine?

Answer 8

Pheochromocytoma & hypertensive emergency

Question 9

What is interesting about Phenoxybenzamine?

Answer 9

Slightly Alpha-1 selective but more importantly it irreversibly binds and is long acting.

Question 10

What are Yohimbe and Rauwolscine?

Answer 10

Alpha-2 selective antagonist

Question 11

What kind of agonists are the Alpha Blockers?

Answer 11

All are competitive agonist except except Phenoxybenzamine.

Question 12

What is the consequence of Non selective Alpha Blocker use?

Answer 12

A Baroreceptor mediated reflex tachycardia due to:

1: BP pressure drop
2: Block of modulation @ Alpha-2 receptor

Question 13

What drug can be used to counteract the effects (hypertension) of drug (cocaine amphetamine ) overdose?

Answer 13

Alpha Blocker

Question 14

What are Alpha-2 receptors?

Answer 14

Presynaptic autoreceptors with modulating effect by inhibiting Adenylate Cyclase and reducing the generation of cAMP and reduction of release of transmitter