Various Antihypertensive Drugs For Parenteral Use In The Management Of Malignant Hypertension And Other Hypertensive Crises


Mechanism of action

Onset of action Peak effect

Method of Duration of action administration

Advantages Disadvantages Side effects


Sodium Direct arteriolar nitroprusside vasodilation and venodilation


Trimethaphan camsylate


Labeta loi




Direct arteriolar vasodilation

Ganglionic blockage with venodilation and arteriolar vasodilation

Direct venodilation at low doses; combined venodilation and arteriolar dilation at higher doses Selective ay and noncardioselective (3-blocker; arteriolar and venous dilation


1-2 min



10-15 min




Phentolamine Nonselective a-blocker 2-3 min

Direct arteriolar vasodilation

10-30 min

Decrease sympathetic nervous system activity via CNS ot2 stimulation, decrease systemic vascular resistance Sympathetic dysfunction owing to central and peripheral catecholamine dysfunction; decreased SVR, decreased CO


5-50 min

5 min

30-60 min

2-3 min after infusion stopped

5-10 min after infusion stopped

1-5 min after infusion stopped

16-18 h

15-30 min

Continuous infusion: Initial, 0.5 |Jg/kg/min Average, 3 |Jg/kg/min Maximum, 10 |Jg/kg/min

IV minibolus: 50-100 mg IV given rapidly over 5-10 min. Total dose, 150-600 mg

Continuous infusion: Initial, 0.5 mg/min Maximum, 5.0 mg/min

Continuous infusion: Initially, 5 |Jg/min Increase by 5 [Jg/min over 3-5 min

IV minibolus: Initial, 20 mg over 2 min Then 40-80 mg over 10 min. Maximum, 300 mg

IV bolus: 1-5 mg over 5 min

Intramuscular: Initial, 0.5-1.0 mg 2-4 m g over 3 h 2-4 mg over 3-12 h

Precise titration of BR Consistently effective when other drugs fail. Parenteral agent of choice for hypertensive crises Long duration of action. Constant monitoring not required after initial titration

Blocks barorecep-tor-mediated sympathetic cardiac stimulation

Theoretic advantages over nitroprusside in setting of myocardial ischemia Continuous monitoring not required

Monitoring in ICU required

Sustained hypotension with C1\IS and myocardial ischemic can occur. Reflex sympathetic cardiac stimulation Parasympathetic blockade

Fails to control BP in some patients

ß-blockage can worsen congestive heart failure, bronchospasm, heart block

Useful in catecho la mine-related crises

Short duration of action

IV bolus: 5-10 mg over 20-30 min or continuous infusion 400 [Jg/mL solution Loading dose: 200-300 [Jq/min for 30-60 minlVlaintenance infusion: 50-150 |Jg/min IV of 250-500 mg over 6-8 h

Proven efficacy Delayed onset and safety in of action, hypertensive crises unpredictable of pregnancy hypotensive effect

None—not recommended for use in hyperten-

None—not recommended for use in hyperten-

N a usea, vomiting, apprehension. Thiocyanate toxicity with prolonged infusion, renal insufficiency

Nausea, vomiting, hyperglycemia, myocardial ischemia, uterine atony

Dry mouth, blurred vision, urinary retention, paralytic ileus, respiratory arrest

Headache, nausea, vomiting, palpitations, abdominal pain

Nausea, vomiting, paresthesias, headache, bradycardia

Tachycardia, arrhythmias, nausea, vomiting, diarrhea, exacerbation of peptic ulcer disease Headache, angina

Delayed onset of action, unpredictable hypotensive effect

Delayed onset of action, unpredictable hypotensive effect


Nasal congestion, CNS sedation, bradycardia, exacerbates peptic ulcer disease, depression

Discontinue if thiocyanate level >10 mg/dL

Contraindicated in aortic dissection, cerebrovascular disease, myocardial ischemia

Tilt-bed enhances effect; tachyphylaxis after 24-48 h; contrai ndicated in respiratory insufficiency and glaucoma; potentiates succinylcholine Dilates intracoronary collaterals

Contra indicated in pheoc hromocytoma, heart failure, asthma, heart block >1 degree, after coronary artery bypass graft surgery Nitroprusside equally efficacious in catecholamine-related crises

Contrai ndicated in aortic dissection, atherosclerotic coronary vascular disease

Contrai ndicated in hypertensive encephalopathy, CNS catastrophe

Contrai ndicated in hypertensive encephalopathy, CNS catastrophe, cumulative hypotensive response

BP—blood pressure; CNS—central nervous system; CO—cardiac output; ICU—intensive care unit; IV—intravenous; SVR—systemic vascular resistance.

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