Sympathomimetics

Question 1

What is a monoamine?

Answer 1

-one amino group connected to aromatic ring by two-carbon chain
-serotonin, dopamine, Norepinephrine, epinephrine, Histamine

Question 2

What is a catecholamine?

Answer 2

monoamine + catechol group [benzene w/2 hydroxyl groups]
-dopamine, Norepinephrine, epinephrine

Question 3

Describe the metabolism of catecholamines.

Answer 3

COMT: liver, nerve terminals; metabolism of circulating and administered catecholamines
MAO: liver, nerve terminals, kidney, gut; surface membrane protein of mitochondria

Question 4

What effects are observed at a1 (Gq) receptor?

Answer 4

Vasoconstriction (innervated), Pupillary dilation, Ejaculation, Inhibition of micturition, GI inhibition

Question 5

What effects are observed at a2 (Gi) receptor?

Answer 5

Vasoconstriction (uninnervated), Prejunctional inhibition of NE release, In CNS: decrease cardiovascular SNS input

Question 6

What effects are observed at B1 (Gs) receptor?

Answer 6

Cardiac stimulation (innervated), Secretion of renin

Question 7

What effects are observed at B2 (Gs) receptor?

Answer 7

Cardiac stimulation (uninnervated, minor), Bronchodilation, Uterine relaxation, GI inhibition, Vasodilation (uninnervated)

Question 8

What receptor is not metabolized by both MAO and COMT?

Answer 8

B2

Question 9

What agonists are Norepinephrine selective for?

Answer 9

-a1 and B1
-metabolized by MAO and COMT

Question 10

What agonists are Epinephrine selective for?

Answer 10

a1 (high doses), B1, and B2
-extra methyl group makes for B2 selectivity
-metabolized by MAO and COMT

Question 11

What agonists are Dopamine selective for?

Answer 11

low doses- D1 & B1
high doses- a1

Question 12

What is a1 clinically manipulated for?

Answer 12

Agonists-
Nasal decongestion
Vascular failure in shock and tachycardia
Antagonists-
Hypertension
Benign prostatic hyperplasia
Pheochromocytoma

Question 13

What is Phenylephrine?

Answer 13

-direct a1 agonist
-metabolized by MAO
-nasal decongestant

Question 14

What are imidazolines?

Answer 14

-partial agonists at a-receptors
-much more hydrophobic/lipophillic

Question 15

What is a2 clinically manipulated for?

Answer 15

Agonist
-Hypertension
-Pain
-Glacoma

Question 16

What is Clonidine?

Answer 16

-direct a2 agonist
-Hypertension, Neuropathic pain, ADHD
-imidazoline structure noted

Question 17

What is the relationship with Methyldopa and Methyldopate?

Answer 17

Methyldopa (Aldomet) is a prodrug given orally due to low water solubility
Methyldopate is a prodrug with good water solubility given parenteral
-hypertension

Question 18

What a2 agonist can help with treatment of glaucoma?

Answer 18

Brimonidine
-inhibits production and increase outflow of aqueous humor; decreases intraocular pressure

Question 19

What is B1 clinically manipulated for?

Answer 19

Agonist
-shock
-Congestive heart failure
Antagonist
-Hypertension
-Angina
-Arrhythmia’s
-Congestive heart failure

Question 20

What is B2 clinically manipulated for?

Answer 20

Agonist
-asthma
-premature labor
Antagonist
-Glaucoma (not common)

Question 21

What is B3 clinically manipulated for?

Answer 21

Agonist
-overactive bladder

Question 22

What is isoproterenol?

Answer 22

-B1 & B2 selective
-used to increase heart rate, patients with systolic dysfunction, asthma and COPD

Question 23

What is the baroreceptor reflex?

Answer 23

-detects changes in blood pressure
low blood pressure: induces tachycardia and vasoconstriction to increase BP
high blood pressure: induces bradycardia to decrease BP

Question 24

What are the B2 selective agonists that are Resorcinol derivatives?

Answer 24

-Metaproterenol (Alupent, Metaprel)
-Terbutaline (Bricanyl, Brethine)
-used for Asthma, COPD, premature labor

Question 25

What are the B2 selective agonists that are meta hydroxymethyl derivatives?

Answer 25

-Albuterol (Ventolin, Proventil)
-Salmeterol (Serevent)
-Formoterol (Foradil)
-used for Asthma, COPD