Hypotensive Agents Flashcards
(62 cards)
What is the mechanism of action of phentolamine?
Non-selective alpha-adrenergic antagonist
Phentolamine blocks both alpha-1 and alpha-2 adrenergic receptors.
What is the typical onset time of phentolamine when given intravenously?
1–2 minutes
Which clinical scenario would phentolamine be most appropriate?
Hypertensive crisis due to pheochromocytoma
What is the typical duration of action of phentolamine?
10–30 minutes
What is a major side effect of phentolamine use?
Reflex tachycardia
Is Phentolamine commonly used to treat extravasation of vasopressors like norepinephrine?
Yes
Can Phentolamine increase blood pressure by stimulating alpha-adrenergic receptors?
No – It blocks alpha receptors, leading to vasodilation and decreased blood pressure.
Is reflex tachycardia a known side effect of phentolamine?
Yes
Does Phentolamine selectively block alpha-1 receptors only?
No – It is a non-selective alpha blocker (alpha-1 and alpha-2).
Is Phentolamine contraindicated in patients with known coronary artery disease?
Yes
What receptors does phentolamine block?
Alpha-1 and alpha-2 adrenergic receptors.
What is the primary clinical use of phentolamine in anesthesia or emergency medicine?
Reversal of local vasoconstriction from vasopressor extravasation; hypertensive crisis due to pheochromocytoma.
What is the usual IV dosage for treating hypertensive emergencies?
5 mg IV bolus; may be repeated as needed.
Describe the cardiovascular response caused by phentolamine.
Vasodilation leading to reduced blood pressure, often accompanied by reflex tachycardia.
Why should phentolamine be used with caution in patients with coronary artery disease?
Reflex tachycardia and hypotension can worsen myocardial ischemia.
What is the mechanism of action of sodium nitroprusside?
Direct nitric oxide donor causing vasodilation
What is the typical onset of action for sodium nitroprusside when given intravenously?
Immediate (within seconds)
Which of the following is a serious potential side effect of sodium nitroprusside?
Cyanide toxicity; cumulative daily dose of 500mcg/kg or rate of 2mcg/kg/min
What is the usual starting dosage for sodium nitroprusside IV infusion?
0.25-5mcg/kg/min
What is the duration of action of sodium nitroprusside?
Less than 5 minutes
Does Sodium nitroprusside lower blood pressure by releasing nitric oxide, which leads to both arterial and venous dilation?
Yes
Do the effects of sodium nitroprusside continue for several hours after stopping the infusion?
No – The effect stops within minutes after discontinuation.
Is Sodium nitroprusside safe for long-term use in all patients?
No – Risk of cyanide toxicity limits long-term use.
Is Sodium nitroprusside photosensitive and must be protected from light?
Yes