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Flashcards in adrenoceptor blockers Deck (51):
1

 All active by
 Oral route
 Parenteral route

alpha blocking drugs

2

IRREVERSIBLE LONG-ACTING

 Prototype
 Only slightly alpha1 selective
 Short elimination half life
 Long duration of action (48 hours)
 Binds covalently to the alpha receptors

PHENOXYBENZAMINE

3

DoA of PHENOXYBENZAMINE

48 hours)

4

REVERSIBLE SHORT-ACTING

• Prototype
• Nonselective (alpha1=alpha2)
 Duration of action
 Oral (2-4 hours)
 IV (20-40 minutes)

PHENTOLAMINE

5

ALPHA1 SELECTIVE

 Prototype
 Selective reversible alpha1 blocker
 Duration of action 8-24 hours
 Doxasozin, terazosin and tamsulosin

PRAZOSIN

6


• Prototype
• Selective alpha2 competitive blockers
• Used primarily in research application

YOHIMBINE, RAUWOLSCINE

7

NONSELECTIVE BLOCKERS
 Most important effects are on the ??

CVS system

8


 Predictable result of the use of an agonist in a patient who has received
an alpha-blocker
 Reversal in the BP effect of large doses of epinephrine
 From pressor response (alpha receptors) to a depressor response (beta receptors)
 Not observed with phenylephrine or NE because they lack sufficient beta2 effects

EPINEPHRINE REVERSAL

9


 Block alpha1 receptors much more effectively
 Cause much less tachycardia than the nonselective blockers when reducing BP

SELECTIVE ALPHA1 BLOCKERS

10


• Tumor that secretes cathecolamines

pheochromocytoma

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type of BLOCKERS
• Severe hypertension caused by overdose with drugs of abuse such as amphetamine, cocaine, or phenylpropanolamine

NONSELECTIVE ALPHA

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type of BLOCKERS
 Prazosin, doxazosin, and terazosin are used in hypertension
 Used together with tamsulosin for urinary hesitancy and prevention of urinary retention with benign prostatic hyperplasia


SELECTIVE ALPHA

13

Prazosin, doxazosin, and terazosin Used together with ? for urinary hesitancy and prevention of urinary retention with benign prostatic hyperplasia

tamsulosin

14

• TOXICITY of alpha blockers

Main manifestation is orthostatic hypotension

15


 Competitive pharmacologic antagonists
 Propranolol is the prototype
 Developed for chronic oral use
• Bioavailability and duration of action vary widely

BETA BLOCKING DRUGS

16

Beta1 receptor selectivity

Acebutolol
Atenolol
Esmolol
Metoprolol

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Advantage when treating patients with asthma

Beta1 receptor selectivity
PARTIAL AGONIST ACTIVITY

18

Nonselective beta-blockers

 Nadolol
 Propranolol
 Timolol
 Pindolol

19

 Combined alpha and beta-blockers
 Optically active

Labetalol
 Carvedilol

20

PARTIAL AGONIST ACTIVITY
 ”Intrinsic sympathomimetic activity”

 May be an advantage in treating patients with asthma
 At maximum dose, can cause some bronchodilatation

Pindolol
 Acebutolol
 Labetalol

21


 ”Membrane stabilizing ability”
 Disadvantage when a beta-blocker is used topically in the eye because it decreases protective reflexes and increases the risk of corneal ulceration

LOCAL ANESTHETIC ACTIVITY

22

LOCAL ANESTHETIC ACTIVITY

 Acebutolol
 Labetalol
 Metoprolol
 Propranolol
 Pindolol

23


• Short-acting ester
• Used only parenterally

ESMOLOL

24


4. Longest acting beta-blocker

NADOLOL

25


 Less lipid soluble
 Enter the CNS to a lesser extent

ACEBUTOLOL, ATENOLOL and NADOLOL

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 EFFECTS of beta blockers in CVS

 Decrease BP
 Antagonize renin secretion
 (-) inotropic effect
 (-) chronotropic effect

27

 EFFECTS of beta blockers in RESPIRATORY

Bronchoconstriction
Increase airway resistance

28

EFFECTS of beta blockers in EYE

• Decrease intraocular pressure
• Decrease production of aqueous humor

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EFFECTS of beta blockers inMETABOLIC AND ENDOCRINE

• Reduce insulin secretion
• Caution for insulin dependent DM

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 CLINICAL USES of beta blockers

 Open-angle glaucoma
 Hypertension
 Angina
• Arrhythmias
• Chronic heart failure
• Pheochromocytoma

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TOXICITY in CVS

1. CVS
1. Bradycardia
2. AV blockade
3. Heart failure

32

TOXICITY in RESPIRATORY

1. Worsen the asthma

33

TOXICITY in CNS


1. Sedation
2. Fatigue
3. Sleep alteration
4. Depression
5. Psychosis

34

TOXICITY in CNS


1. Sedation
2. Fatigue
3. Sleep alteration
4. Depression
5. Psychosis

35

Conversion of the pressor response to epinephrine (typical of large doses) to a blood
pressure–lowering effect; caused by α blockers, which unmask the β2 effects of epinephrine

Epinephrine reversal

36

Partial agonist action by adrenoceptor blockers; typical of several β blockers (eg, pindolol,
acebutolol)

Intrinsic sympathomimetic
activity (ISA)

37

Local anesthetic action; typical of several β blockers (eg, propranolol)

Membrane-stabilizing
activity (MSA)

38

Hypotension that is most marked in the upright position; caused by venous pooling (typical of α blockade) or inadequate blood volume (caused by blood loss or excessive diuresis)

Orthostatic hypotension

39

A tumor consisting of cells that release varying amounts of norepinephrine and epinephrine
into the circulation

Pheochromocytoma

40

Drugs used in glaucoma.
Beta blockers

Timolol, others

41

Drugs used in glaucoma
Prostaglandins

Latanoprost, others

42

Drugs used in glaucoma.
Cholinomimetics

Pilocarpine, physostigmine

43

Drugs used in glaucoma.
Alpha agonists
Nonselective:

epinephrine

44

Drugs used in glaucoma.
Alpha2-selective agonists

Apraclonidine, brimonidine

45

Drugs used in glaucoma.
Carbonic anhydrase inhibitors

Acetazolamide, dorzolamide

46

Drugs used in glaucoma.
Osmotic agents

Mannitol

47

Clinical Applications
Pheochromocytoma, antidote to overdoseof α agonists

Phentolamine

48

Clinical Applications
Pheochromocytoma,
carcinoid, mastocytosis, Raynaud’s
phenomenon

phenoxybenzamine

49

Clinical Applications
Hypertension, benign
prostatic hyperplasia

PRAZOSIN

50

Clinical Applications
Obsolete use for
erectile dysfunction •
research use

YOHIMBINE

51

Clinical Applications
Angina, arrhythmias
(treatment and prophylaxis), hypertension, thyrotoxicosis,
tremor, stage fright,
migraine

PROPRANOLOL

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