Selective1-blockers promote vascular smooth muscle relaxation by antagonizing the binding of norepinephrine to the
1-adrenergic receptor in this tissue. Drugs in this class (prazosin, terazosin, and doxazosin) have a similar effect on
smooth muscle in the prostate and therefore are indicated for
both hypertension and prostatic hypertrophy with symptoms
of lower urinary tract outlet obstruction. The principal target
population for which monotherapy with these drugs might
be considered is elderly men with both hypertension and
prostatic hypertrophy.
63 An added benefit of selective
-blocker therapy in older patients at increased risk for coronary artery disease–related events is a modest reduction in
low-density lipoprotein cholesterol and triglyceride levels accompanied by a slight increase in high-density lipoprotein
cholesterol levels.
64
However, thereisconcernabout anincreased incidence of first-dose orthostatic hypotension in this
same patient population because older individuals have diminished autonomic nervous system compensatory responsestohypotensivestimuli.
65
Other Drugs
Direct-Acting Vasodilators
Hydralazine and minoxidil are drugs that act directly on vascular smooth muscle cells to promote vasorelaxation although the cellular mechanisms by which this is accomplished differ. These potent hypotensive agents usually are
prescribed as part of a therapeutic regimen for the patient
whosehypertensionisrefractorytomultidrugtherapy.
66
Hydralazine also has been used effectively as part of a multidrug
regimen in the management of heart failure. Recently, hydralazine combined with isosorbide dinitrate has been reported
to reduce cardiovascular mortality more than conventional
therapyinAfricanAmericanswithsevereheartfailure
67
and
historically more than the same therapy in Caucasian Americans,
68
althoughthefactorscontributingtothisethnicdifference have not been defined clearly. Both drugs reduce
peripheral resistance and have far less effect on venous capacitance. Decreasing arterial pressure by this mechanism
causes reflex activation of the sympathetic nervous system
and the renin-angiotensin system, resulting in tachycardia
andrenal retentionof sodium.
69
Consequently, thesedrugs
are given most frequently with diuretics and -blockers,
combined–-blockers such as labetalol or carvediolol, or
sympatholyticagentssuchasclonidineorreserpine.
70,7
Selective1-blockers promote vascular smooth muscle relaxation by antagonizing the binding of norepinephrine to the
1-adrenergic receptor in this tissue. Drugs in this class (prazosin, terazosin, and doxazosin) have a similar effect on
smooth muscle in the prostate and therefore are indicated for
both hypertension and prostatic hypertrophy with symptoms
of lower urinary tract outlet obstruction. The principal target
population for which monotherapy with these drugs might
be considered is elderly men with both hypertension and
prostatic hypertrophy.
63 An added benefit of selective
-blocker therapy in older patients at increased risk for coronary artery disease–related events is a modest reduction in
low-density lipoprotein cholesterol and triglyceride levels accompanied by a slight increase in high-density lipoprotein
cholesterol levels.
64
However, thereisconcernabout anincreased incidence of first-dose orthostatic hypotension in this
same patient population because older individuals have diminished autonomic nervous system compensatory responsestohypotensivestimuli.
65
Other Drugs
Direct-Acting Vasodilators
Hydralazine and minoxidil are drugs that act directly on vascular smooth muscle cells to promote vasorelaxation although the cellular mechanisms by which this is accomplished differ. These potent hypotensive agents usually are
prescribed as part of a therapeutic regimen for the patient
whosehypertensionisrefractorytomultidrugtherapy.
66
Hydralazine also has been used effectively as part of a multidrug
regimen in the management of heart failure. Recently, hydralazine combined with isosorbide dinitrate has been reported
to reduce cardiovascular mortality more than conventional
therapyinAfricanAmericanswithsevereheartfailure
67
and
historically more than the same therapy in Caucasian Americans,
68
althoughthefactorscontributingtothisethnicdifference have not been defined clearly. Both drugs reduce
peripheral resistance and have far less effect on venous capacitance. Decreasing arterial pressure by this mechanism
causes reflex activation of the sympathetic nervous system
and the renin-angiotensin system, resulting in tachycardia
andrenal retentionof sodium.
69
Consequently, thesedrugs
are given most frequently with diuretics and -blockers,
combined–-blockers such as labetalol or carvediolol, or
sympatholyticagentssuchasclonidineorreserpine.
70,7
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