Adrenergics - Indirect Acting Agonists

Question 1

What is an indirect acting adrenergic agonist?

Answer 1

releases endogenous NE from nerve terminals

Question 2

What is tyramine’s only mechanism of action?

Answer 2

Indirect release of NE (ONLY INDIRECT)

Question 3

Where is Tyramine found?

Answer 3

In foods, not a drug

Question 4

What types of foods contain high levels of tyramine?

Answer 4

Fermented foods -> wine, beer, some cheeses and sausages

Question 5

Without any drug interactions, what normally happens to tyramine?

Answer 5

Degraded in liver by MAO (rapidly) and tyramine never enters system/has a negative impact

Question 6

What happens (clinically) if tyramine acts?

Answer 6

HTN (crisis) b/c too much release of NE

Question 7

Why can tyramine be an issue with some drugs?

Answer 7

Drugs that block MAO, will lead to increase in Tyramine in system -> HTN crisis

Question 8

What are the mechanisms of action of amphetamine? (broadly)

Answer 8

Direct and indirect action -> increase NE release and stimulate adrenergic receptors

Question 9

What are the mechanisms of action of amphetamine (specifically)?

Answer 9

Release NE from adrenergic neurons
Weakly stimulate A and B receptors
Inhibits NET -> important b/c it competes with NE for uptake back into cell leaving more NE in synaptic cleft

Question 10

Where does amphetamine act?

Answer 10

CNS (a lot), weaker direct actions in PNS

Question 11

What are the therapeutic uses of amphetamine?

Answer 11

narcolepsy, ADD (paradoxal effect in kids)

Question 12

What is the route of administration of amphetamine?

Answer 12

Oral

Question 13

What is the relative half life of amphetamine?

Answer 13

Long (several hours)

Question 14

How does amphetamine increase presence of NE?

Answer 14

Competes for uptake into storage granules, so increased NE in cytoplasm of cell -> a carrier moves it out into synaptic cleft. This system overrides the MAO pathway too

Question 15

What is the mechanism of action of ephedrine?

Answer 15

Direct - A and B agonist

Indirect - releases NE to activate adrenergic receptors

Question 16

What is the main effect of an indirect agonist (general)?

Answer 16

Cause increase release of NE, so going to do all the things NE does. Increase BP and TVR, but no change in HR

Question 17

How is ephedrine administered?

Answer 17

Orally

Question 18

Where does ephedrine act? (CNS or PNS)

Answer 18

CNS

Question 19

What is clinically significant about ephedrine?

Answer 19

Was found in many herbal concoctions with unknown consumption of high amounts -> importance of knowing what herbal supplements a pt is on

Question 20

What is the mechanism of action of pseudoephedrine?

Answer 20

Direct - A1 activity with little B2 agonist activity

Question 21

What is the route of administration of pseudoephedrine?

Answer 21

orally

Question 22

What is the major therapeutic use of pseudoephedrine?

Answer 22

Nasal decongestant - b/c of A1 agonist effects

Question 23

What are the side effects of all A agonists and why? (3)

Answer 23

Throbbing headaches due to potent vasoconstriction
cerebral hemmorhage - b/c increased systemic blood pressure
Restlessness and anxiety

Question 24

What are the side effects of all B agonists and why?

Answer 24

Increased heart rate (palpatations)
Cardiac arrhythmias (b/c increase HR)
Pericardial pain (angina) b/c of increased HR ->especially in pts with CAD
restlessness and anxiety