31
Adrenergic blocking
antagonists
Learning objectives
Upon completion of this chapter, you should be able to:
1.
Describe the effects of adrenergic blocking agents on adrenergic receptors, correlating these effects with
their clinical effects.
2.
Describe the therapeutic actions, indications, pharmacokinetics, contraindications and cautions, most
common adverse reactions and important drug–drug interactions associated with adrenergic blocking
agents.
3.
Discuss the use of adrenergic blocking agents across the lifespan.
4.
Compare and contrast the prototype drugs labetalol, phentolamine, doxazosin, propranolol and atenolol with
other adrenergic blocking agents.
5.
Outline the care considerations, including important teaching points, for people receiving an adrenergic
blocking agent.
Glossary of key terms
adrenergic-receptor-site specificity:
a drug’s affinity for only adrenergic receptor sites; certain drugs may have specific affinity for
only alpha- or only beta-adrenergic receptor sites
alpha
1
-selective adrenergic blocking agents:
drugs that block the postsynaptic alpha
1
-receptor sites, causing a decrease in vascular
tone and a vasodilation that leads to a fall in blood pressure; these drugs do not block the presynaptic alpha
2
-receptor sites, and
therefore the reflex tachycardia that accompanies a fall in blood pressure does not occur
beta-adrenergic blocking agents:
drugs that, at therapeutic levels, selectively block the beta-receptors of the sympathetic nervous
system
beta
1
-selective adrenergic blocking agents:
drugs that, at therapeutic levels, specifically block the beta
1
-receptors in the
sympathetic nervous system while not blocking the beta
2
-receptors and resultant effects on the respiratory system
bronchodilation:
relaxation of the muscles in the bronchi, resulting in a widening of the bronchi; an effect of sympathetic stimulation
phaeochromocytoma:
a tumour of the chromaffin cells of the adrenal medulla that periodically releases large amounts of
noradrenaline and adrenaline into the system with resultant severe hypertension and tachycardia
sympatholytic:
a drug that lyses, or blocks, the effects of the sympathetic nervous system
Test your current knowledge of adrenergic blocking antagonists with a PrepU Practice Quiz!
NON-SELECTIVE ADRENERGIC
BLOCKING AGENTS
amiodarone
carvedilol
labetalol
NON-SELECTIVE
ALPHA-ADRENERGIC
BLOCKING AGENTS
phentolamine
ALPHA
1
-SELECTIVE
ADRENERGIC BLOCKING
AGENTS
alfuzosin
doxazosin
prazosin
tamsulosin
terazosin
NON-SELECTIVE BETA-
ADRENERGIC BLOCKING
AGENTS
nebivolol
oxprenolol
pindolol
propranolol
sotalol
timolol
BETA
1
-SELECTIVE ADRENERGIC
BLOCKING AGENTS
atenolol
betaxolol
bisoprolol
esmolol
metoprolol
