Adrenergic Pharmacology II

Question 1

Phenylephrine acts on which receptors?

Answer 1

Low doses- A1

Higher doses- B1

Question 2

Phenylephrine associated with which G protein? What are the systemic effects?

Answer 2

Acts on Gq protein.

Causes increased BP and increased TPR

Question 3

Clinical indications for Phenylephrine (4)

Answer 3

1. Antihypotensive agent
2. Paroxysmal atrial tachycardia
3. Nasal decongestant
4. Mydriatic (accommodation still present because M3 receptors are normal)

Question 4

4 examples of A2 agonists

Answer 4

Clonidine (catapres)
A-methyldopa (aldomet)
Apraclonidine (lodipine)
Brimonidine (alphagan)

Question 5

Which A2 agonists are used to treat HTN? How do they work?

Answer 5

Clonidine and A-methyldopa.

They activate A2 receptors which decreases sympathetic outflow, which decreases BP

Question 6

Which A2 agonists treat glaucoma? How do they work?

Answer 6

Apraclonidine and brimonidine.
By binding to the A2 receptors on the ciliary body epithelium, they cause a decrease in aqueous humor production which causes a decrease in ocular pressure

Question 7

Metaproterenol (metaprel) selectively acts on which receptor? which receptor might also be activated?

Answer 7

Metaproterenol acts selectively on B2 receptors but may act on B1 receptors

Question 8

Therapeutic uses for metaproterenol (2)

Answer 8

1. Long-term treatment of COPD and asthma

2. Acute bronchospasm

Question 9

Terbutaline (bricanyl) acts on which receptor?

Answer 9

Terbutaline acts on B2 receptors

Question 10

Therapeutic uses for Terbutaline?

Answer 10

1. Long-term treatment of COPD and asthma
2. Acute bronchospasm
3. Emergency treatment of status asthmaticus (IV)

Question 11

Albuterol acts on which receptor preferably?

Answer 11

Albuterol is a B2 receptor agonist

Question 12

Ritodrine acts on which receptor?

Answer 12

Ritodrine is a B2 receptor agonist

Question 13

Previous therapeutic uses for Ritodrine?

Answer 13

Uterine relaxant to arrest premature labor or prolong pregnancy

Question 14

Fenoldopam acts preferably on which receptor? What other receptor may it act on and how?

Answer 14

Fenoldopam acts preferentially as a D1 agonist but may stimulate A2 autoreceptors (which would decrease NE release)

Question 15

Clinical use of Fenoldopam? Why?

Answer 15

Used for hypertensive crisis

Causes vasodilation in renal, mesenteric, peripheral, and coronary vasculature

Question 16

Isoproterenol acts on which receptors? Which receptors does it not act on?

Answer 16

Isoproterenol is a strong B1 and B2 receptor agonist. It does not act on A receptors

Question 17

Cardiovascular and respiratory effects of Isoproterenol?

Answer 17

Cardiovascular: decrease TPR, increase HR (reflex tachycardia due to decreased BP), increase inotropy
Respiratory: bronchodilation (not as much as albuterol)

Question 18

Therapeutic uses for Isoproterenol (3)

Answer 18

1. Bradycardia
2. AV block
3. Torsades de Pointes

Question 19

Dobutamine can act on which receptors (3)? Which receptor does it prefer to act on?

Answer 19

Dobutamine can act on B1, B2, and A2.

It preferentially binds to B1 at therapeutic doses

Question 20

Cardiovascular effects on dobutamine (3)

Answer 20

1. Positive inotropic effect (more than isoproterenol)
2. Positive chronotropic effect (somewhat)
3. TPR is not affects because B2 and A1 balance