Sympathomimetic- Phenylephrine

Question 1

Is a 3-hydroxyphenylethylamine and a synthetic noncatecholamine. Differs from epinephrine in that it lacks a 4-hydroxyl group on the benzene ring

Answer 1

Phenylephrine

Question 2

phenylephrine mimics effects of NE -how is potency and duration different

Answer 2

less potent than NE and longer lasting then NE

Question 3

which receptor does phenylephrine directly stimulate

Answer 3

alpha-1 adrenergic receptors

Question 4

which receptor does phenylephrine indirectly stimulate

Answer 4

beta adrenergic receptors

Question 5

phenylephrine dose to stimulate alpha 1 receptors vs alpha 2 receptors

Answer 5

smaller doses stimulate alpha 1 than the dose to stimulate alpha 2

Question 6

CNS stimulation for phenylephrine

Answer 6

minimal

Question 7

IV bolus dose for phenylephrine

Answer 7

50-200mcg iv

Question 8

name two type of patient conditions phenylephrine is beneficial to

Answer 8

patients with CAD and AS

Question 9

why is phenylephrine good for patients with CAD and AS

Answer 9

it increases coronary perfusion pressure without chronotropic side effects- unlike most sympathomimetics

Question 10

what is the primary effect of phenleyphrine

Answer 10

vasoconstriction

Question 11

what is the continuous infusion dose of phenlyephrine

Answer 11

20-100mcg/min

Question 12

how is phenylephrine used for SVT

Answer 12

reflex vagal effects are used to slow HR

Question 13

when phenylephrine is used with nitric oxide what is the effect

Answer 13

can improve arterial oxygenation

Question 14

what is the effect of rapid administration of 1mg/kg to anesthetized patients with cad

Answer 14

transient impairment of lv global function

Question 15

oral clonidine premedication plus phenylephrine create what response

Answer 15

auguemtns the pressor response to phenylephrine presumably due to clonidine induced potentiation of alpha 1 mediated vasoconstricito

Question 16

Rapid IV injection of phenlyphrine to patients with CAD produce what effects to the heart

Answer 16

vasoconstriction, increase BP, decreased CO

Question 17

why does phenlephrine create a decrease in CO

Answer 17

due to increased after load - likely due to baroreceptor mediated bradycardia in response to increases in DBP

Question 18

phenylephrine increases blood flow in these two places

Answer 18

coronary blood flow

pulmonary artery pressure

Question 19

phenylephrine decreases blood flow in these three places

Answer 19

renal
splanchnic
cutaneous blood flow

Question 20

which receptor disrupts the potassium load from shifting into the cells while phenylephrine is infusing

Answer 20

alpha

Question 21

what is the result of phenylephrine infusion and potassium infusion.

Answer 21

increased serum potassium because potassium is unable to shift into the cells

Question 22

in the absence of acute potassium load- does phenylephrine affect plasma potassium concentration

Answer 22

no

Question 23

phenylephrine 3 things seen with overdose

Answer 23

HTN
tachycardia
baroreceptor medicated Bradycardia

Question 24

which medication is appropriate to treat phenylephrine toxicity

Answer 24

phentolamine- alpha 1 antagonist

Question 25

vascular absorption of phenlyphrine when used as a topical or injected vasconstrictors in the surgical field COULD result in what complication

Answer 25

overdose

Question 26

where does blood pool in phenlyphrine overdose

Answer 26

pulmonary vascular beds

Question 27

the natural protection of pulmonary vascular overload is to maintain what function

Answer 27

CO

Question 28

can we beta block a patient with phenylephrine overdose

Answer 28

Since Beta-1 receptor blockades reduces CO treatment of phenylephrine induced hypertensive crisis with Beta adrenergic blocking drugs is CONTRAINDICATED can cause cardiac collapse

Question 29

which medication do we administer to help with phenylephrine overdose

Answer 29

NTG and phentolamine

Question 30

do we always treat phenylephrine overdose

Answer 30

Systemic hypertension induced by IV administered administered alpha agonists may not require treatment. This is b/c duration of action of IV phenylephrine and epinephrine are brief and hypertension may resolve spontaneously
Severe hypertension treatment must not decrease the ability of the stressed myocardium to increase contractility and HR. Thus vasodilating drugs such as nitroprusside or NTG maybe helpful (as well as phentolamine)

Question 31

Explain phenylephrine’s indirect acting action:

Answer 31

its ability to evoke the release of norepinephrine

Question 32

explain phenylephrine’s direct acting effect:

Answer 32

Principally stimulates alpha-1 adrenergic receptors

Question 33

Is Phenylephrine primarily direct or indirect acting?

Answer 33

Direct

*stimulation of alpha 1