Adrenergic Blockers Flashcards Preview

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Flashcards in Adrenergic Blockers Deck (36):
1

Phenoxybenzamine

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

2

Reversible alpha blockers

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)

3

alpha 1 selective blockers

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

These are all REVERSIBLE blockers

4

alpha 2 selective blockers

Yohimbine

this is a REVERSIBLE blocker

5

Irreversible alpha blocker

phenoxybenzamine; nonselective

6

CVS effects of alpha blockers

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)

7

adverse effects of alpha blockers

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

8

Effects of alpha blockers on urinary bladder

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

9

specific alpha 1A antagonist

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

10

alpha blockers used to treat pheochromocytoma

phenoxybenzamine & phentolamine

11

Drugs used to treat hypertension

prazosin (selective alpha1 blocker)

12

patient presents with decreased heart rate, sweating, malignant hypertension

Dx: pheochromocytoma

increased epi bc tumor-->

13

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

phentolamine

14

alpha blocker used to treat peripheral vascular disease & Raynauds

Prazosin (selective alpha1 blocker)

15

What's causing urinary difficulty in BPH?

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!!

16

Toxicity of alpha blockers

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

17

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

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

18

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

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

19

longterm use of an agonist has what effect on receptors

down regulation of receptors

20

longterm use of an antagonist has what effect on receptors

up regulation of receptors

21

why don't you abruptly stop beta blockers

rebound hypertension

22

B1 blockers safe for asthmatics

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

"a BEAM of beta blockers"

23

Why is Timolol the preferred beta blocker to treat glaucoma?

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

24

beta blocker used to treat pheochromocytoma

Labetalol

25

side effects of beta blockers

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

26

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

because beta blockers depress myocardial contractility & excitability

27

premonitory symptoms of hypoglycemia

tachycardia, tremor, anxiety

can be masked by beta blockers

28

Beta blockers used to treat heart failure

1. metoprolol
2. bisoprolol
3. carvedilol

29

beta blockers used to treat cardiac arrhythmias & MOA

Sotalol works by increasing the AV nodal refractory period

has anti arrhythmic effects involving ion channel blockade in addition to its beta blocking action

30

how do beta blockers treat hypertension

1. decreasing CO
2. decrease renin secretion

31

beta blocker used during surgery as an antiarrhythmic

Esmolol; half-life = 10m

32

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

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

33

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

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

34

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

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

35

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

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

36

epinephrine reversal

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.