Alpha blockers

Question 1

antagonists shift the dose response curve

Answer 1

to the right

Question 2

all alpha blocking agents are ______ except _______

Answer 2

competitive antagonists

phenoxybenzamine

Question 3

phenoxybenzamine is a

Answer 3

non-competitive irreversible antagonist

Question 4

nonocompetitive irreversible antagonists

Answer 4

diminish maximum response

shift curve to the right

Question 5

competitive antagonists

Answer 5

the maximum effect is the same

shift curve to the right

Question 6

alpha blockade decreases

Answer 6

vasoconstriction, blood pressure, PVR

Question 7

reflex tachycardia occurs with alpha blockade due to

Answer 7

1. decreased BP decreases vagal tone by baroreceptor reflex

2. a2 blockage increases NE–> B1

Question 8

postural hypotension occurs due to

Answer 8

blockage of a1 receptors in venous smooth muscle

Question 9

blocking alpha receptors means that giving epi will have effects

Answer 9

similar to those of isoproterenol

Question 10

alpha blockers are widely used to treat

Answer 10

BPH (decreased resistance to urine flow)

Question 11

phentolamine blocks

Answer 11

a1 and a2

Question 12

phentolamine CV effects

Answer 12

1. block a1 –> decrease PVR

2. block a2 –> increased NE release

Question 13

phentolamine short term tx

Answer 13

htn crises in pheochromocytoma or MAO + tyramine

Question 14

if NE/vasoconstrictor is accidentally injected into tissues, treat necrosis with

Answer 14

phentolamine

Question 15

phenoxybenzamine effects lasts

Answer 15

days, until new receptors are produced

Question 16

phenyoxybenzamine effects are most pronounced when

Answer 16

standing up

Question 17

phenoxybenzamine is used to treat

Answer 17

pheochromocytoma (too much sympathetic tone)

Question 18

phenyoxybenzamine causes severe hypotension if

Answer 18

hypovolemic
using vasodilators
using ETOH

Question 19

pheochromocytoma is indicated by

Answer 19

sudden onset severe htn, tachycardia, arrhythmia

tumor which releases Epi/NE

Question 20

your patient is an old man with hypertension and BPH, what’s your DOC

Answer 20

prazosin

Question 21

prazosin is less likely to increase HR bc

Answer 21

its highly selective for a1

Question 22

give prazosin

Answer 22

2x daily, duration of action 7-10 hrs

Question 23

decrease dose of prazosin

Answer 23

CHF

Question 24

first dose phenomenon is associated with

Answer 24

prazosin, terazosin, doxazosin

Question 25

first dose phenomenon is

Answer 25

postural hypotension/syncope 30-90 minutes after first dose of drug.

To avoid, start prazosin at night

Question 26

alpha blockers + ED drugs (sildenafil) =

Answer 26

SEVER HYPOTENSION

Question 27

sildenafil

Answer 27

viagra

Question 28

2 a1 specific blockers that are similar to prazosin, but are dosed once daily

Answer 28

terazosin, doxazosin

Question 29

tamsulosin is selective for

Answer 29

a1a

Question 30

a1a is found in

Answer 30

prostate

Question 31

a1b is found in

Answer 31

blood vessels

Question 32

tamsulosin BP effects

Answer 32

FEW bc it’s more selective

Question 33

your patient has BPH and postural hypotension when he takes a1 receptors. what are your DOC

Answer 33

tamsulosin, alfuzosin

Question 34

alfuzosin is

Answer 34

tamsulosin + dizziness

Question 35

anti-clonidine

Answer 35

yohimbine

Question 36

yohimbine is dangerous in

Answer 36

htn

Question 37

yohimbine is

Answer 37

a2 selective antagonist

Question 38

a2 antagonism

Answer 38

increases NE release —> increased sympathetic tone