Hypotensive Agents Flashcards
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
Is Sodium nitroprusside commonly used for controlled hypotension during surgery?
Yes
What is the primary clinical use of sodium nitroprusside?
Management of hypertensive emergencies and controlled hypotension during surgery.
How quickly does sodium nitroprusside begin to act when administered IV?
Immediately—onset is within seconds
What major complication is associated with prolonged or high-dose infusion of sodium nitroprusside?
Cyanide or thiocyanate toxicity.
How is sodium nitroprusside administered?
As a continuous IV infusion.
What monitoring is important when a patient is receiving sodium nitroprusside?
Continuous blood pressure monitoring and monitoring for signs of toxicity (e.g., metabolic acidosis, confusion).
Can Sodium nitroprusside cause Coronary Steal?
Yes
What is the mechanism of action of nitroglycerin?
Conversion to nitric oxide leading to vasodilation
Which vessels does nitroglycerin primarily affect at lower doses?
Veins
What is the typical onset time for IV nitroglycerin?
15–30 seconds
Which of the following is a common side effect of nitroglycerin?
Headache
Which clinical scenario is nitroglycerin NOT typically used for?
Bradycardia
What is typical Nitroglycerin concentration and dosage?
Concentration of 100mcg/ml; Infusion rates of 0.5-5mcg/kg/min
Is Nitroglycerin metabolized to nitric oxide, which increases cGMP and causes smooth muscle relaxation?
Yes
Is the duration of IV nitroglycerin longer than 1 hour?
No – Duration is typically 3–5 minutes after stopping infusion.
Does Nitroglycerin cause arterial dilation at all doses?
No – It primarily causes venodilation at low doses; arterial dilation at higher doses.
Does sublingual nitroglycerin have a rapid onset?
Yes – Onset is typically 1–3 minutes.
Should Nitroglycerin be used with caution in patients with right ventricular infarction?
Yes
What is the usual starting IV infusion dose of nitroglycerin?
Infusion rates of 0.5-5mcg/kg/min
What is a serious risk associated with long-term nitroglycerin use?
Tolerance (tachyphylaxis), nitrate dependence, metabolism can cause Methemoglobinemia (rarely)
What are two primary clinical indications for nitroglycerin use?
- Angina pectoris
- Hypertensive emergency
How is nitroglycerin administered in acute angina?
Sublingually (0.3–0.6 mg tablets) every 5 minutes as needed, up to 3 doses.
What is the primary mechanism of action of hydralazine?
Direct arterial vasodilation via smooth muscle relaxation
Which type of blood vessel is primarily affected by hydralazine?
Arteries
What is the usual IV dose of hydralazine for hypertensive emergency in adults?
5–10 mg
What is a common side effect of hydralazine?
Reflex tachycardia (bad for patients that are elderly and have CAD)
Which clinical scenario is hydralazine most often used in?
Hypertensive emergency during pregnancy
Does Hydralazine act primarily as a venous dilator?
No – It is a direct arterial vasodilator.
Is Hydralazine commonly used to manage eclampsia-related hypertension?
Yes
Is Hydralazine’s onset of action is about 15 minutes when given IV?
Yes
One potential adverse effect of chronic hydralazine use is a lupus-like syndrome?
Yes
Can Hydralazine cause a decrease in cardiac output?
No – It may increase cardiac output due to reflex sympathetic activation.
What is the typical IV dose range of hydralazine for acute hypertension?
5–10 mg IV every 4–6 hours as needed.
What is the onset time of IV hydralazine?
15 minutes
How long does the effect of IV hydralazine typically last?
2–4 hours.
Name one major side effect of hydralazine due to reflex sympathetic stimulation.
Tachycardia or palpitations.
What autoimmune condition can be triggered by chronic use of hydralazine?
Drug-induced lupus erythematosus.
Why should hydralazine be used cautiously in patients with coronary artery disease?
Because it can cause reflex tachycardia, increasing myocardial oxygen demand and potentially precipitating angina.
