Chapter_018

advertisement
Chapter 18
Adrenergic Antagonists
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
Adrenergic Antagonists




Cause direct blockade of adrenergic
receptors
With one exception, all produce reversible
(competitive) blockade
Most adrenergic antagonists are more
selective than the adrenergic agonists.
Two major groups


Alpha-adrenergic blocking agents
Beta-adrenergic blocking agents
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
2
Adrenergic Antagonists




Alpha-adrenergic antagonists I: therapeutic
and adverse response to alpha blockade
Alpha-adrenergic antagonists II: properties of
individual alpha blockers
Beta-adrenergic antagonists I: therapeutic
and adverse responses to beta blockade
Beta-adrenergic antagonists II: properties of
individual beta blockers
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
3
Therapeutic Applications of
Alpha Blockade

Essential hypertension



Lowers blood pressure by blocking alpha1
receptors on arterioles and veins, causing
vasodilation
Reversal of toxicity from alpha1 agonists
Benign prostatic hyperplasia

Reduced contraction of smooth muscle in the
bladder neck and prostatic capsule
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
4
Therapeutic Applications of
Alpha Blockade

Pheochromocytoma




Catecholamine-secreting tumor
Usually located in adrenal medulla
Principal cause of hypertension is usually
activation of alpha1 receptors, but beta1 receptors
can also contribute
Treatment: best option is surgery
• Inoperable tumor: alpha1 antagonists suppress
hypertension
• Surgery: before surgery, manipulation of tumor can
cause massive catecholamine release
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
5
Therapeutic Applications of
Alpha Blockade

Raynaud’s disease




Peripheral vascular disorder
Vasospasms in the toes and fingers
Suppress symptoms by preventing alphamediated vasoconstriction
Ineffective against other peripheral vascular
disorders that involve inappropriate
vasoconstriction
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
6
Adverse Effects of Alpha1 Blockade



Detrimental effects result from blockade of
alpha1 receptors
Effects from alpha2 receptors are minor
Orthostatic hypotension





Blockade of alpha receptors on veins
Reduced muscle tone in the venous wall
Upon standing, blood pools in the veins
Return of blood to the heart reduced
Cardiac output decreased: blood pressure drops
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
7
Adverse Effects of Alpha1 Blockade

Reflex tachycardia


Nasal congestion


Dilates the blood vessels of the nasal mucosa
Inhibition of ejaculation



Reflex to increase heart rate via the autonomic nervous
system (ANS)
Alpha1 activation required for ejaculation
Impotence is reversible; resolves when drug is discontinued
Sodium retention and increased blood volume


Reduced BP promotes renal retention of sodium and water
Usually combined with diuretic when used for hypertension
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
8
Adverse Effects of Alpha2 Blockade

The most significant adverse effect
associated with alpha2 blockade—
potentiation of the reflex tachycardia
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
9
Alpha-Adrenergic Antagonists II







Prazosin
Terazosin
Doxazosin
Tamsulosin
Alfuzosin
Phentolamine
Phenoxybenzamine
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
10
Prazosin




Actions and uses
Pharmacokinetics
Adverse effects
Preparations, dosage, and administration
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
11
Terazosin




Actions and uses
Pharmacokinetics
Adverse effects
Preparations, dosage, and administration
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
12
Doxazosin




Actions and uses
Pharmacokinetics
Adverse effects
Preparations, dosage, and administration
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
13
Tamsulosin





Actions and uses
Pharmacokinetics
Adverse effects
Drug interactions
Preparations, dosage, and administration
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
14
Alfuzosin





Actions and uses
Pharmacokinetics
Adverse effects
Drug interactions
Preparations, dosage, and administration
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
15
Phentolamine



Actions and uses
Adverse effects
Preparations, dosage, and administration
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
16
Phenoxybenzamine



Actions and uses
Adverse effects
Preparations, dosage, and administration
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
17
Beta-Adrenergic Antagonists I

Therapeutic applications of beta blockade



Angina pectoris
Hypertension
Cardiac dysrhythmias
 Myocardial infarction
 Heart failure
 Hyperthyroidism
 Migraine
 Stage fright
 Pheochromocytoma
 Glaucoma
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
18
Beta-Adrenergic Antagonists I

Adverse effects of beta blockade

Adverse effects involve both beta1 and beta2
blockade.
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
19
Beta-Adrenergic Antagonists I

Adverse effects of beta1 blockade





Bradycardia
Reduced cardiac output
Precipitation of heart failure
AV heart block
Rebound cardiac excitation
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
20
Beta-Adrenergic Antagonists I

Adverse effects of beta2 blockade


Bronchoconstriction
Inhibition of glycogenolysis
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
21
Beta-Adrenergic Antagonists II:
Propranolol




Pharmacologic effects
Pharmacokinetics
Therapeutic uses
Adverse effects




Bradycardia
AV heart block
Heart failure
Rebound cardiac excitation
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
22
Beta-Adrenergic Antagonists II:
Propranolol

Adverse effects (cont’d)




Bronchoconstriction
Inhibition of glycogenolysis
CNS effects
Precautions, warnings, and contraindications



Severe allergy
Diabetes
Cardiac, respiratory, and psychiatric disorders
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
23
Beta-Adrenergic Antagonists II:
Propranolol

Drug interactions



Calcium channel blockers
Insulin
Preparations, dosage, and administration



General dosing considerations
Preparations
Dosage
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
24
Beta-Adrenergic Antagonists II:
Metoprolol






Pharmacologic effects
Pharmacokinetics
Therapeutic uses
Adverse effects
Precautions, warnings, and contraindications
Preparations, dosage, and administration
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
25
Beta-Adrenergic Antagonists II:
Other Beta-Adrenergic Blockers






Receptor specificity: selective blockade
Pharmacokinetics
Therapeutic uses
Adverse effects
Intrinsic sympathomimetic activity (partial
agonist activity)
Dosage and administration
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
26
Download
Related flashcards

Heart diseases

42 cards

Heart diseases

42 cards

Cardiac arrhythmia

57 cards

Cardiac arrhythmia

56 cards

Create Flashcards