Lecture 8: Sympatholytics

Question 1

a1 receptor ANTAGONIST

Answer 1

-phenoxybenzamine
-phentoalmine
-prazosin
-terazosin
-doxazosin

Question 2

a1 ANTAGONIST side effects

Answer 2

-orthostatic HTN
-inhibit ejaculation
-nasal stiffness
-tachycardia

Question 3

non-selective a receptor ANTAGONISTs

Answer 3

-B-Haloalkylamines
-imidazolines

Question 4

B-haloalkylamines

Answer 4

-non selective a ANTAGONIST
-also blocks Acetylcholine, histamine, and serotonin receptors
-IRREVERSIBLE (form covalent bond)

Question 5

B-haloalkylamines example

Answer 5

-phenoxybenzamine

Question 6

B-haloalkylamines mechanism

Answer 6

Slide 13

Question 7

Imidazolines

Answer 7

-non selective a ANTAGONIST
-also blocks 5-HT receptors
-also muscarinic and histmaine AGONIST
-reversible

Question 8

Imidazoline effects

Answer 8

-vasodilator BUT induces tachycardia
-blocks presynaptic a2 receptors may promote release of NE

Question 9

Imidazoline medication

Answer 9

-phentolamine

Question 10

a1 vs non selective a blockers

Answer 10

slide 15

Question 11

Reversible vs irreversible a antagonism

Answer 11

slide 16

Question 12

Phenoxybenzamine action

Answer 12

-IRREVERSIBLE
-a1 and a2 ANTAGONIST
-new receptors must be synthesized in order to restore receptor function leading to a long drug effect

Question 13

Phentolamine action

Answer 13

-competitive (REVERSIBLE)
-a1 and a2 ANTAGONIST

Question 14

Phenozybenzamine and phentolamine use

Answer 14

-perioperative management of pheochromocytoma (tumor of adrenal medulla that results in excessive epinephrine and NE synthesis and release)

Question 15

Phenozybenzamine and phentolamine problems

Answer 15

-not useful in treatment of HTN due to a2 effects

Question 16

Effect of blocking a2

Answer 16

-greater release of NE at the heart
-increase HR

Question 17

a1 ANTAGONISTS

Answer 17

-vary in half life
-undergo high metbaolism
-excreted in bile
-“-osins”
-quinazolines

Question 18

a1 ANTAgonist effects

Answer 18

-vasoDILATION
-relax smooth muscle in enlarged prostate and bladder base

Question 19

Quinizolines

Answer 19

-a1 ANTAGONIST
-prazosin, terazosin, doxazosin
-produce vasodilation without causing tachycardia or increased Cardiac Output

Question 20

Prazosin mechanism

Answer 20

=decrease TPR
-activate baroreceptor reflex
-increase NE release to heart
-increase HR via B2
-negative feedback via a2 receptors in myocardia mitigates NE release

Question 21

Tamsulosin (Flomax)

Answer 21

-a1a ANTAgonist
-very selective to prostate (rich in a1a receptors)
-less prone to induce fall in BP compared to a1 blockers

Question 22

Benign Prostatic Hyperplasia (BPH)

Answer 22

-problem with voiding leads to overactive bladder
-stimulation of a1a makes bladder resist pissing
-treat with a1 blocker (tamulosin)

Question 23

a2 ANTAgonists

Answer 23

-yohimbine

Question 24

yohimbine

Answer 24

-indole alkaloid
-found in Rubaceae and other trees
-block a2
-increase sympathetic discharge
-might treat male impotence