prazosin.
Fenoldopam, nitroprusside, and propranolol are the drugs in the list that have been
used in hypertensive emergencies. Fenoldopam and nitroprusside are used by
infusion only, but nitroprusside releases nitric oxide, which acts on intracellular
guanylyl cyclase.
Fenoldopam used in severe hypertensive emergencies, is short-acting, acts on a G-
protein-coupled receptor, and must be given by intravenous infusion
TABLE 11–2 Mechanisms of action of vasodilators.
Mechanism of Smooth
Examples
Muscle Relaxation
Dihydropyridines: vessels > heart
Reduction of calcium influx via
L-type channels
Verapamil, diltiazem: heart ≥ vessels
Nitroprusside(short
acting/min), hydralazine (hours)
Release of nitric oxide from hydralazine has a duration of action of
drug or vascular endothelium hours, whereas nitroprusside acts for
seconds to minutes and must be given by
intravenous infusion
Hyperpolarization of vascular
smooth muscle through Minoxidil sulfate, diazoxide
opening of potassium channels
Activation
Fenoldopam
of dopamine D1 receptors
,
,
,
Fenoldopam, nitroprusside, and propranolol are the drugs in the list that have been
used in hypertensive emergencies. Fenoldopam and nitroprusside are used by
infusion only, but nitroprusside releases nitric oxide, which acts on intracellular
guanylyl cyclase.
Fenoldopam used in severe hypertensive emergencies, is short-acting, acts on a G-
protein-coupled receptor, and must be given by intravenous infusion
TABLE 11–2 Mechanisms of action of vasodilators.
Mechanism of Smooth
Examples
Muscle Relaxation
Dihydropyridines: vessels > heart
Reduction of calcium influx via
L-type channels
Verapamil, diltiazem: heart ≥ vessels
Nitroprusside(short
acting/min), hydralazine (hours)
Release of nitric oxide from hydralazine has a duration of action of
drug or vascular endothelium hours, whereas nitroprusside acts for
seconds to minutes and must be given by
intravenous infusion
Hyperpolarization of vascular
smooth muscle through Minoxidil sulfate, diazoxide
opening of potassium channels
Activation
Fenoldopam
of dopamine D1 receptors
,
,
,
