Sympathomimetics

Question 1

Ephedrine dose, onset, peak, duration?

Answer 1

dose: 2.5-10 mg
onset: < 1 minute
peak: 2 - 5 minutes
duration: 10 - 60 minutes

Question 2

Is ephedrine an alpha 1, alpha 2, beta 1, and/or beta 2 agonist?

Answer 2

INDIRECT alpha 1 and beta 1

Question 3

Phenylephrine (Neosynephrine) dose, onset, peak, duration?

Answer 3

dose: 40-100 mcg
onset: < 1 minute
peak: 1 minute
duration: 15 - 30 minutes

Question 4

Is phenylephrine (Neosynephrine) an alpha 1, alpha 2, beta 1, and/or beta 2 agonist?

Answer 4

DIRECT Alpha 1

Question 5

Epinephrine dose, onset, peak, duration?

Answer 5

dose: 2-20 mcg/min
onset: 30 seconds
peak: 3 minutes
duration: 10 minutes

Question 6

Alpha 1 stimulation causes?

Answer 6

Increase inotropy and vasoconstriction

Question 7

Alpha 2 stimulation causes?

Answer 7

Vasodilation due to CNS presynaptic inhibition of norepinephrine

Question 8

Beta 1 stimulation causes?

Answer 8

Increase inotropy, chronotropy, and dromotropy

Question 9

Beta 2 stimulation causes?

Answer 9

Increase inotropy, chronotropy, vascular dilation, and bronchial dilation

Question 10

DA1 stimulation causes?

Answer 10

Vasodilation

Question 11

DA2 stimulation causes?

Answer 11

Inhibition of norepinephrine release

Question 12

Is epinephrine an alpha 1, alpha 2, beta 1, and/or beta 2 agonist?

Answer 12

All of the above

Question 13

Phenylephrine (Neosynephrine) mechanism of action.

Answer 13

DIRECT alpha agonist - binds to and agonizes sympathetic adrenergic Gq-receptors

ultimately stimulates calcium release by the sarcoplasmic reticulum (in arteries and veins, this leads to constriction)

Question 14

Cardiac effects of phenylephrine.

Answer 14

increases PVR, afterload, and BP

mild increases in chronotropy and inotropy at high doses

Question 15

How is phenylephrine metabolized?

Answer 15

monoamine oxidase (MAO)

Question 16

Ephedrine mechanism of action.

Answer 16

INDIRECT alpha 1 and beta 1 agonist - causes norepinephrine to be released, resulting in the stimulation of alpha 1 and beta 1 receptors

DIRECT beta 2 agonist (mild)

Question 17

Pulmonary and cardiac effects of ephedrine.

Answer 17

pulmonary - mild bronchodilation d/t mild beta 2 stimulation

cardiac - increases PVR, afterload, and BP; increases chronotropy and inotropy; decreases uterine blood flow

Question 18

How is ephedrine metabolized?

Answer 18

hepatic metabolism

renal elimination

Question 19

How is epinephrine metabolized?

Answer 19

monoamine oxidase (MAO) and hepatic

Question 20

What is the dose in mcg/mL of epinephrine 1:200,000? 1:100,000? 1:1000? 1:400,000?

Answer 20

1: 200,000 = 5 mcg/mL
1: 100,000 = 10 mcg/mL
1: 1000 = 1000 mcg/mL (or 1 mg/mL)
1: 400,000 = 2.5 mcg/mL

Question 21

What medication is used to reverse an overdose of phenylephrine?

Answer 21

hydralazine

Question 22

What is the max dose of ephedrine? and why?

Answer 22

50mg (the amount that’s in one ephedrine vial)

because any more than that will deplete norepinephine stores. (since ephedrine causes its release)