Sympatholytics- Alpha Drugs

Question 1

Name three drugs that are competitive alpha adrenergic antagonists

Answer 1

phentolamine, prazosin, & yohimbine

Question 2

what is different about the receptor binding of phenoxbenzamine

Answer 2

binds covalently to produce an IRREVERSIBLE and insurmountable type of alpha blockade

Question 3

how does the binding of phenoxybenzamine get reversed

Answer 3

effects cannot be reversed by sympathomimetics- effects are terminated by METABOLISM

Question 4

what does phenoxybenzamine treat

Answer 4

high BP

heavy sweating due to tumor of the adrenal glands (pheochromocytoma)

Question 5

which two drugs are nonselective alpha antagonist

Answer 5

phentolamine & phenoxybenzamine

Question 6

phentolamine BP effects

Answer 6

peripheral vasodilation, decrease BP

Question 7

phentolamine manifest its effects___ and last ____

Answer 7

2 min

10-15 min

Question 8

what are the heart rate effects of phentolamine

Answer 8

cardiac dysrhythmias

angina

Question 9

why are there associated cardiac effects with phentolamine

Answer 9

alpha receptor blockade permits enhanced neural release of NE increase HR and CO

Question 10

where does phentolamine have direct action

Answer 10

vascular smooth muscle

Question 11

PNS is predominant after phentolamine what does this cause (3)

Answer 11

hyperperistalsis
abdominal pain
diarrhea

Question 12

where is phentolamine metabolized

what percent is unchanged by the kideny

Answer 12

liver

10% unchanged by the kidney

Question 13

what two condition does phentolamine treat

Answer 13

HTN emergencies from pheochromocytoma

autonomic nervous system hyperreflexia

Question 14

phentolamine push dose

Answer 14

30-70mcg/kg (1-5mg)

Question 15

phentolamine continuous infusion

Answer 15

0.1-2mg/min

Question 16

phentolamine as a local infiltration dose of extravasation of a sympathomimetic medication

Answer 16

5-15mg in 10cc ns

Question 17

phenoxybenzamine what is the GI absorption

Answer 17

incomplete

Question 18

phenoxybenzamine onset of blockade

Answer 18

slow up to 60 min to peak after IV administration. This accounts for the modification of the drug molecule to become pharmacologically active

Question 19

phenoxybenzamine elimination half time

Answer 19

24 hour

Question 20

can phenoxybenzamine accumulate

Answer 20

yes with repeated doses

Question 21

phenoxbenzamine receptor binding

Answer 21

alpha 1 more than 2

Question 22

phenoxybenzamine what are the systemic bp changes in a normovolemic patient

Answer 22

little changes

Question 23

for phenoxybenzamine what is prominent in the presence of preexisting hypertension or hypovolemia

Answer 23

orthostatic hypotension

Question 24

what are the changes to cerebral and coronary vascular resistance with phenoxybenzamine

Answer 24

no changes

Question 25

what is the result of phenoxybenzamine for maternal patients

Answer 25

If given during maternal treatment can cause neonatal hypotension and respiratory distress in first 72 hours of life

Question 26

phenoxybenzamine BP effect CO effect renal blood flow effect

Answer 26

decreasing BP increased CO renal blood flow is not greatly altered unless preexisting renal vasoconstriction is present

Question 27

phenoxybenzamine blood loss or vasodilation effects?

Answer 27

exaggerated BP decreases in response to blood loss of vasodilating drugs such as volatile anesthetics.

Question 28

phenoxybenzamine chronic therapy effects

Answer 28

sedation

Question 29

phenoxybenzamine sinus effect

Answer 29

Nasal stuffiness is d/t unopposed vasodilation in mucous membranes in the presence of alpha adrenergic block

Question 30

phenoxybenzamine alpha receptor stimulation prevents epi from doing what

Answer 30

prevents the inhibitory action of epi on the secretion of insulin

Question 31

phenoxybenzamine po dose

Answer 31

0.5-1mg/kg PO

Question 32

when do we give phenoxybenzamine

Answer 32

preop to control BP in patients with pheochromocytoma

Question 33

phenoxbenzamine HCT effects

Answer 33

expansion of intravascular fluid volume by relieving intense peripheral vasoconstriction thus will see a fall in HCT

Question 34

does phenoxbenzamine help with PVD

Answer 34

no because PVD is skeletal muscle blood flow and not cutaneous blood flow

Question 35

other than administration for pheochromocytoma what else can we give phenoxybenzamine for?

Answer 35

raynauds disease- due to the cutaneous vasoconstriction

Question 36

once volume has been restored on a patient and we still see tissue ischemia from vasoconstriction what medication relieves the vasconstriciton

Answer 36

phenoxybenzamine

Question 37

yohimibine receptor

Answer 37

alpha 2 receptor antagonist

Question 38

yohimibine past uses current uses

Answer 38

past impotence | current orthostatic hypotension

Question 39

doxazosin receptor

Answer 39

alpha 1 antagonist

Question 40

doxazosin uses

Answer 40

HTN | benign prostatic hypertrophy

Question 41

prazosin receptor

Answer 41

alpha 1 antagonist

Question 42

prazosin uses

Answer 42

pheochromocytoma

Question 43

terazosin receptor

Answer 43

alpha 1 antagonist

Question 44

terazosin uses

Answer 44

BPH

Question 45

tamsulosin receptor

Answer 45

alpha 1 antagonist

Question 46

tamsulosin uses

Answer 46

BPH

Question 47

tamsulosin which medication decreases the clearance of it

Answer 47

cimetidine

Question 48

tolazoline receptor

Answer 48

non selective alpha antagonists

Question 49

tolazoline uses

Answer 49

pul HTN in new borns replaced by nitric oxide

Question 50

alpha 2 agonist pharmacology effects (3)

Answer 50

sedation, hypotension, bradycardia

Question 51

alpha 2 receptors are found where

Answer 51

CNS- Brainstem and locus ceruleus

Question 52

where are alpha 2 receptors pre or post synpatic

Answer 52

presynaptic

Question 53

which mechanism do alpha 2 receptors use

Answer 53

negative feed back mechanism

Question 54

as a result of alpha 2 negative feed back what is not being released from the presynaptic nerve terminal

Answer 54

NE

Question 55

inhibition of alpha 2 receptors has what effect on glucose and insulin

Answer 55

inhibition of insulin release and induction of glucagon from pancreas

Question 56

is binding of alpha 2 agonist reversible

Answer 56

yes

Question 57

withdrawal from alpha 2 agonist can result in what

Answer 57

increase HR and HTN

Question 58

clonidine cardiac effects?

Answer 58

dose dependent decreases in HR and BP

Question 59

clonidine what two things does it treat

Answer 59

resistant HTN and tremors from central stimulant medication

Question 60

what forms do we give clonidine

Answer 60

IV, PO, transdermal

Question 61

clonidine terminal half life

Answer 61

12-16 hours

Question 62

clonidine partial agonists on which receptors

Answer 62

400:1 alpha 2 over alpha 1

Question 63

clonidine metabolized where and excreted where

Answer 63

liver and excreted in the bile and feces

Question 64

Dexmedetomidine: receptor

Answer 64

Selective alpha 2 agonist with 1,600:1 preference of alpha 2

Question 65

dex IV dose

Answer 65

0.1-1.5mcg/kg/min

Question 66

dex terminal elimination half life

Answer 66

2 hours

Question 67

when is dex used most often

Answer 67

icu or OR as a sedative and analgesic d/t its central sympatholytic effects

Question 68

dex is under goes what in the liver and excreted mostly in the

Answer 68

biotransformation in liver and excreted in the urine

Question 69

dex withdrawal

Answer 69

tachycardia HTN Anxiety

Question 70

Dexmedetomidine

Answer 70

Large IV boluses (0.25 to 1 mcg/kg over 3-5 min) result in a paradoxical hypertension with a decrease in HR and resembles phenylephrine and is the resultant effect of crossover alpha 1 stimulation.