49
Adrenergic blockers (cont'd)
Nonselective
alpha receptor
antagonist
Phentolamine • IV bolus dose 5 mg.
• Additional bolus
doses every 10 min
as needed to lower
BP to target.
• Used in hypertensive
emergencies
induced by
catecholamine excess
(pheochromocytoma,
interactions between
monamine oxidase
inhibitors and other
drugs or food, cocaine
toxicity, amphetamine
overdose, or clonidine
withdrawal).
Others
Dopamine
1
-
receptor selective
agonist
Fenoldopam • Initial 0.1–0.3 mcg/
kg/min.
• May be increased
in increments of
0.05–0.1 mcg/kg/
min every 15 min
until target BP is
reached.
• Maximum infusion
rate: 1.6 mcg/kg/
min.
• Contraindicated in
patients at risk of
increased intraocular
pressure (glaucoma) or
intracranial pressure
and those with sulfite
allerg y.
ACE inhibitor Enalaprilat • Initial 1.25 mg over
a 5-min period.
• Doses can be
increased up to
5 mg every 6 h as
needed to achieve
BP target.
• Contraindicated in
pregnancy and should
not be used in acute
MI or bilateral renal
artery stenosis.
• Mainly useful
in hypertensive
emergencies associated
with high plasma
renin activity.
• Dose not easily
adjusted.
• Relatively slow onset
of action (15 min) and
unpredictability of BP
response.
Table 15. Intravenous Antihypertensive Drugs for Treatment
of Hypertensive Emergencies (cont'd)
Class Drug(s) Usual Dose Range Comments
