Adrenergic Blockers

Question 1

Phenoxybenzamine

Answer 1

1. irreversible alpha blocker; insurmountable blockade, forms covalent bond with receptors
2. non-selective alpha 1 & 2
3. only therapeutic drug that has noncompetitive antagonism
4. graphically will level off (flatten on y axis) rather than move to right on x axis

Question 2

Reversible alpha blockers

Answer 2

1. Phentolamine (nonselective alpha 1 & alpha 2)
2. Prazosin (alpha 1 selective)
3. Terazosin (alpha 1 selective)
4. Doxazosin (alpha 1 selective)
5. Tamsulosin (alpha 1 selective)
6. Yohimbine (alpha 2 selective)

Question 3

alpha 1 selective blockers

Answer 3

1. Prazosin
2. Terazosin
3. Doxazosin
4. Tamsulosin (specific alpha 1A antagonist)

These are all REVERSIBLE blockers

Question 4

alpha 2 selective blockers

Answer 4

Yohimbine

this is a REVERSIBLE blocker

Question 5

Irreversible alpha blocker

Answer 5

phenoxybenzamine; nonselective

Question 6

CVS effects of alpha blockers

Answer 6

1. decrease PVR & BP

Convert a pressor response of Epi to a depressor response. Called Epinephrine Reversal

Cause orthostatic hypotension & reflex tachycardia, esp with nonselective blockers due to increase release of NE (due to alpha2 blockade)

Question 7

adverse effects of alpha blockers

Answer 7

Cause orthostatic hypotension & reflex tachycardia, esp with nonselective blockers due to increase release of NE (due to alpha2 blockade)

Question 8

Effects of alpha blockers on urinary bladder

Answer 8

1. alpha 1 receptors are expressed in base of bladder & prostate & blockade–>decrease resistance to flow or urine–> used to tx urinary symptoms in men with BPH

alpha 1A subtype may be the most important subtype in mediating prostate smooth muscle contraction; Tamsulosin=specific alpha 1A antagonist

Question 9

specific alpha 1A antagonist

Answer 9

Tamsulosin

has greater potency than other alpha 1 blockers bc alpha 1A subtype may be the most important subtype in mediating prostate smooth muscle contraction

Question 10

alpha blockers used to treat pheochromocytoma

Answer 10

phenoxybenzamine & phentolamine

Question 11

Drugs used to treat hypertension

Answer 11

prazosin (selective alpha1 blocker)

Question 12

patient presents with decreased heart rate, sweating, malignant hypertension

Answer 12

Dx: pheochromocytoma

increased epi bc tumor–>

Question 13

alpha blocker used to treat HTN due to clonidine withdrawal, cheese reaction

Answer 13

phentolamine

Question 14

alpha blocker used to treat peripheral vascular disease & Raynauds

Answer 14

Prazosin (selective alpha1 blocker)

Question 15

What’s causing urinary difficulty in BPH?

Answer 15

in BPH activation of alpha1A receptors in bladder trigone, prostate & prostatic urethra increases smooth muscle tone

blockade of these receptors relaxes the structures–> increases urinary flow rate & allows more complete emptying of bladder.

DO NOT REVESE THE HYPERPLASIA, only provide symptomatic relief!!

Question 16

Toxicity of alpha blockers

Answer 16

1. orthostatic hypertension
2. reflex tachycardia w nonselective blockers (due to increased NE by alpha2 blockade
   * *tachycardia is less common with alpha1 selective blockers

Question 17

1. drugs with partial agonist activity or “intrinsic sympathomimetic activity
2. what is this?

Answer 17

1. pindolol & acebutolol

2. advantage of treating patients with asthma bc the drugs are less likely to cause bronchospasm

Question 18

1. drugs with local anesthetic activity or ‘membrane stabilizing activity
2. what is this?

Answer 18

1. propranolol

2. the result of blockade of Na channels & can be demonstrated experimentally; no clinical effect

Question 19

longterm use of an agonist has what effect on receptors

Answer 19

down regulation of receptors

Question 20

longterm use of an antagonist has what effect on receptors

Answer 20

up regulation of receptors

Question 21

why don’t you abruptly stop beta blockers

Answer 21

rebound hypertension

Question 22

B1 blockers safe for asthmatics

Answer 22

1. Betaxolol
2. Esmolol
3. Atenolol
4. Metoprolol

“a BEAM of beta blockers”

Question 23

Why is Timolol the preferred beta blocker to treat glaucoma?

Answer 23

when used topically in the eye some beta blockers decrease protective reflexes & increase the risk of corneal ulceration. this is ABSENT in Timolol

Question 24

beta blocker used to treat pheochromocytoma

Answer 24

Labetalol

Question 25

side effects of beta blockers

Answer 25

1. bradycardia 2. bronchospasm* 3. chronic use assoc w increased lipid levels (LDL & TG) 4. may mask premonitory symptoms of hypoglycemia (tachycardia, tremor, anxiety) 5. CNS effects: mild sedation, vivid dreams, rarely depression

Question 26

Why should beta blockers be used cautiously in patients with CHF?

Answer 26

because beta blockers depress myocardial contractility & excitability

Question 27

premonitory symptoms of hypoglycemia

Answer 27

tachycardia, tremor, anxiety can be masked by beta blockers

Question 28

Beta blockers used to treat heart failure

Answer 28

1. metoprolol 2. bisoprolol 3. carvedilol

Question 29

beta blockers used to treat cardiac arrhythmias & MOA

Answer 29

Sotalol works by increasing the AV nodal refractory period has anti arrhythmic effects involving ion channel blockade in addition to its beta blocking action

Question 30

how do beta blockers treat hypertension

Answer 30

1. decreasing CO | 2. decrease renin secretion

Question 31

beta blocker used during surgery as an antiarrhythmic

Answer 31

Esmolol; half-life = 10m

Question 32

Acebutolol: 1. selectivity 2. side effects 3. uses

Answer 32

1. beta1 selective 2. sedation 3. Tx Angina & HTN

Question 33

atenolol: 1. selectivity 2. side effects 3. uses

Answer 33

1. beta1 selective 2. increases lipid levels 3. Tx Angina & HTN

Question 34

Metoprolol: 1. selectivity 2. side effects 3. uses

Answer 34

1. Beta1 selective 2. sedation & increases lipid levels 3. Angina, HTN, post-MI, antiarrhythmic

Question 35

Pindolol: 1. selectivity 2. side effects 3. uses

Answer 35

1. beta 1 & 2 2. partial agonist-->less likely to cause bronchospasm in patients with asthma 3. HTN, Angina

Question 36

epinephrine reversal

Answer 36

alpha blockers convert a pressor response of epinephrine to a depressor response one of the CVS effects of alpha blockers: they cause a lowering of PVR and BP.