Pharmacology Quiz: Hypertensive Urgency Vs Emergency
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Hypertensive Urgency Vs EmergencyQuestion 1 of 20

A 59-year-old woman with a history of severe persistent asthma is admitted with a hypertensive emergency (BP 225/130 mmHg) and signs of encephalopathy. Which of the following intravenous antihypertensive agents should be used with extreme caution or avoided in this patient?

Clevidipine
Labetalol
Fenoldopam
Nitroglycerin
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Pharmacology Quiz: Hypertensive Urgency Vs Emergency

Practice Hypertensive Urgency Vs Emergency in Pharmacology with focused quiz questions that help you check what you know, review explanations, and build confidence with test-style prompts.

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This quiz focuses on Hypertensive Urgency Vs Emergency, giving you a quick way to practice the rules, question types, and explanations that matter most for Pharmacology.

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Question 1

A 59-year-old woman with a history of severe persistent asthma is admitted with a hypertensive emergency (BP 225/130 mmHg) and signs of encephalopathy. Which of the following intravenous antihypertensive agents should be used with extreme caution or avoided in this patient?

  1. Clevidipine
  2. Labetalol (correct answer)
  3. Fenoldopam
  4. Nitroglycerin
Explanation: Labetalol is a beta-blocker with non-selective beta-1 and beta-2 receptor antagonism, as well as alpha-1 blocking activity. The blockade of beta-2 receptors in the lungs can cause bronchoconstriction, which can trigger a severe exacerbation in a patient with asthma. Therefore, non-selective beta-blockers are relatively contraindicated in patients with reactive airway disease.
  • (A) Clevidipine is a calcium channel blocker and does not affect beta-receptors.
  • (C) Fenoldopam is a dopamine-1 agonist.
  • (D) Nitroglycerin is a nitrate vasodilator. None of these other agents pose a significant risk of bronchospasm.

Question 2

A 28-year-old man is brought to the emergency department with agitation, diaphoresis, mydriasis, and chest pain after using cocaine. His blood pressure is 220/130 mmHg and heart rate is 140 bpm. Which medication, if given as monotherapy, could paradoxically worsen hypertension and coronary vasoconstriction?

  1. Phentolamine
  2. Labetalol
  3. Propranolol (correct answer)
  4. Diazepam
Explanation: Cocaine causes a massive release of catecholamines, leading to intense stimulation of both alpha- and beta-adrenergic receptors. Administering a non-selective beta-blocker without alpha-blocking properties, such as propranolol, blocks the beta-2 receptor-mediated vasodilation. This leaves the alpha-1 receptor-mediated vasoconstriction unopposed, which can lead to a paradoxical rise in blood pressure and worsening coronary vasoconstriction.
  • (A) Phentolamine is an alpha-blocker and would be beneficial.
  • (B) Labetalol has both alpha- and beta-blocking properties, which makes it a safer option than a pure beta-blocker, although benzodiazepines are typically first-line.
  • (D) Diazepam, a benzodiazepine, is a first-line treatment for sympathomimetic toxicity, as it reduces central sympathetic outflow.

Question 3

A 66-year-old patient develops a hypertensive emergency (BP 210/125 mmHg) complicated by a rise in serum creatinine from 1.5 to 2.5 mg/dL. An intravenous infusion is started with an agent that not only lowers blood pressure but also improves renal blood flow by stimulating peripheral dopamine-1 (D1) receptors. Which agent was used?

  1. Enalaprilat
  2. Fenoldopam (correct answer)
  3. Sodium nitroprusside
  4. Nicardipine
Explanation: Fenoldopam is a selective peripheral dopamine-1 (D1) receptor agonist. Stimulation of D1 receptors causes vasodilation in the renal, mesenteric, and coronary arteries. This leads to an increase in renal blood flow and can be particularly beneficial in hypertensive emergencies associated with acute kidney injury. None of the other agents share this specific mechanism of action.
  • (A) Enalaprilat (an ACE inhibitor) can worsen renal function in certain settings (e.g., bilateral renal artery stenosis).
  • (C) Sodium nitroprusside is a direct vasodilator with no specific renal-protective mechanism.
  • (D) Nicardipine is a calcium channel blocker and does not act on dopamine receptors.

Question 4

A 70-year-old patient in a nursing home is found to have a blood pressure of 195/105 mmHg. He reports a mild headache but is otherwise at his neurologic baseline. A provider administers a 10 mg immediate-release nifedipine capsule, instructing the patient to bite it and swallow. Which potential adverse event is the primary reason this practice is now strongly discouraged for hypertensive urgencies?

  1. Unpredictable and precipitous drop in blood pressure leading to end-organ ischemia. (correct answer)
  2. A paradoxical hypertensive response due to reflex sympathetic activation.
  3. High incidence of drug-induced gingival hyperplasia with acute dosing.
  4. Rapid development of tolerance, rendering the drug ineffective after one dose.
Explanation: The use of immediate-release oral or sublingual nifedipine for hypertensive urgencies is contraindicated. The primary danger is that it causes rapid, profound, and unpredictable vasodilation, which can lead to a precipitous drop in blood pressure. This can compromise perfusion to vital organs, leading to cerebral ischemia (stroke), myocardial ischemia (heart attack), or renal failure, particularly in elderly patients with pre-existing vascular disease.
  • (B) The response is hypotension, not hypertension.
  • (C) Gingival hyperplasia is a side effect of chronic, not acute, nifedipine use.
  • (D) Tachyphylaxis is not the main acute danger of this practice.

Question 5

A 55-year-old man presents to the emergency department with a sudden onset of "tearing" chest pain radiating to his back. His blood pressure is 210/120 mmHg and heart rate is 115 bpm. Aortic dissection is suspected. What is the most critical initial pharmacotherapeutic goal?

  1. Rapidly decrease systolic blood pressure to <140 mmHg using an intravenous dihydropyridine calcium channel blocker as monotherapy.
  2. Immediately reduce both heart rate to <60 bpm and systolic blood pressure to <120 mmHg, typically with an IV beta-blocker and a vasodilator. (correct answer)
  3. Administer intravenous nitroglycerin to reduce preload and alleviate chest pain while preparing for surgical consultation.
  4. Prioritize heart rate control with an IV beta-blocker, followed by gradual blood pressure reduction over 24-48 hours with oral agents.
Explanation: In a suspected aortic dissection, the primary goals are to rapidly reduce both blood pressure and the rate of rise of systolic pressure (dP/dt), which is related to heart rate. The target is a heart rate <60 bpm and a systolic blood pressure of 100-120 mmHg, achieved within minutes. This is typically accomplished with an IV beta-blocker (e.g., esmolol) to control heart rate and dP/dt, followed by or co-administered with a vasodilator (e.g., sodium nitroprusside or clevidipine) to control blood pressure. A vasodilator alone would cause reflex tachycardia, increasing dP/dt and worsening the dissection.
  • (A) A calcium channel blocker alone would not control heart rate and could cause harmful reflex tachycardia.
  • (C) While nitroglycerin may be used for pain, it is not the primary agent for hemodynamic control in dissection.
  • (D) Blood pressure reduction must be immediate and aggressive, not gradual over days.

Question 6

A patient with an acute aortic dissection requires precise, minute-to-minute control of both heart rate and blood pressure. The surgical team requests an intravenous beta-blocker that can be titrated rapidly with a very short duration of action, allowing for quick reversal if bradycardia or hypotension occurs. Which agent best fits this description?

  1. Metoprolol
  2. Labetalol
  3. Propranolol
  4. Esmolol (correct answer)
Explanation: Esmolol is an ultra-short-acting, cardioselective beta-1 blocker with a half-life of approximately 9 minutes. It is administered via continuous IV infusion and is metabolized by red blood cell esterases. Its rapid onset and offset allow for precise, minute-to-minute titration of its effects. This makes it the ideal agent for critical situations like aortic dissection where tight hemodynamic control is essential and rapid reversal of effects may be needed.
  • (A), (B), and (C) Metoprolol, labetalol, and propranolol are also available in IV formulations but have much longer half-lives (hours), making them less easily titratable and their effects less rapidly reversible.

Question 7

A patient's hypertensive emergency has been successfully controlled for 12 hours with an intravenous esmolol infusion. The patient is now asymptomatic with a stable blood pressure of 150/90 mmHg. What is the most critical step before discontinuing the esmolol infusion?

  1. Administer a diuretic to prevent rebound fluid retention from occurring.
  2. Check for orthostatic hypotension to ensure the patient can tolerate future ambulation.
  3. Rapidly taper the esmolol infusion over 30 minutes to avoid severe withdrawal symptoms.
  4. Initiate an appropriate oral antihypertensive agent and allow sufficient time for it to take effect. (correct answer)
Explanation: When transitioning patients from intravenous to oral antihypertensive therapy, the critical principle is ensuring continuous blood pressure control without dangerous gaps in coverage. This becomes especially important with short-acting IV agents like esmolol, which has an elimination half-life of only 9 minutes. The correct approach is option D: initiating an appropriate oral antihypertensive and allowing adequate time for therapeutic levels to be established before discontinuing the IV infusion. This "bridging" strategy prevents rebound hypertension, which can be life-threatening in patients who just experienced a hypertensive emergency. Most oral antihypertensives require 30 minutes to 2 hours to reach peak effect, so you must start the oral agent and wait for this overlap period. Option A is incorrect because diuretics aren't routinely needed during esmolol discontinuation, and rebound fluid retention isn't a primary concern with beta-blocker cessation. Option B, while good general practice, isn't the most critical step specific to safely discontinuing esmolol - blood pressure control takes priority. Option C contains a dangerous misconception: esmolol's ultra-short half-life means tapering isn't necessary like it would be with longer-acting beta-blockers. Rapid discontinuation is actually safe with esmolol due to its quick elimination. Remember this key transition principle: with short-acting IV antihypertensives, always establish therapeutic levels of the replacement therapy before stopping the infusion. The shorter the half-life of the IV drug, the more critical this timing becomes to prevent rebound hypertension.

Question 8

A 68-year-old male with a history of poorly controlled hypertension presents for a routine check-up. He is asymptomatic. His blood pressure is 200/115 mmHg. Physical examination, including a funduscopic and neurologic exam, is unremarkable. Serum creatinine is at his baseline of 1.2 mg/dL. What is the most appropriate next step in management?

  1. Reinstitute and intensify his oral antihypertensive regimen and arrange for close follow-up within a few days. (correct answer)
  2. Administer a single dose of oral clonidine 0.2 mg and observe for 3-4 hours before discharge.
  3. Admit the patient for an intravenous infusion of nicardipine to lower the mean arterial pressure by 20% over the first hour.
  4. Administer a dose of immediate-release sublingual nifedipine and recheck blood pressure in 30 minutes.
Explanation: This patient presents with hypertensive urgency: severely elevated blood pressure without signs or symptoms of acute, ongoing target-organ damage. The goal is to lower blood pressure gradually over 24-48 hours. The most appropriate management is to adjust the patient's long-term oral medication regimen and ensure close follow-up. Rapid reduction in blood pressure is not necessary and can be harmful, potentially causing ischemia.
  • (B) While a single dose of an oral agent like clonidine can be used, the primary goal is establishing a sustainable long-term regimen, not just temporary reduction. This option is less optimal than a comprehensive medication adjustment.
  • (C) Intravenous therapy is reserved for hypertensive emergencies, where there is evidence of acute target-organ damage. This would be overly aggressive and potentially dangerous.
  • (D) Immediate-release nifedipine (sublingual or oral) is contraindicated due to its potential to cause a precipitous and unpredictable drop in blood pressure, which can lead to cerebral or myocardial ischemia.

Question 9

A 75-year-old patient with end-stage renal disease and hepatic cirrhosis is in the ICU with a hypertensive emergency. The team needs an easily titratable intravenous calcium channel blocker. Which agent's metabolism and clearance are independent of both renal and hepatic function, making it a theoretically safer choice in this patient?

  1. Nicardipine
  2. Verapamil
  3. Diltiazem
  4. Clevidipine (correct answer)
Explanation: Clevidipine is an ultra-short-acting dihydropyridine calcium channel blocker. It is unique in that it is metabolized by esterases in the blood and extravascular tissues. This route of metabolism is independent of liver (hepatic) or kidney (renal) function, making its clearance predictable even in patients with severe organ dysfunction. This is a significant advantage over other IV agents in patients with multi-organ failure.
  • (A) Nicardipine is metabolized by the liver.
  • (B) Verapamil is metabolized by the liver.
  • (C) Diltiazem is metabolized by the liver.

Question 10

A patient with a hypertensive emergency secondary to acute decompensated heart failure is being treated. The physician wants to primarily reduce cardiac filling pressures (preload). Which intravenous agent would be more selective for this goal compared to an agent that produces balanced arterial and venous dilation?

  1. Nitroglycerin, which is a more potent venodilator at lower doses. (correct answer)
  2. Sodium nitroprusside, which is a more potent venodilator at all doses.
  3. Nicardipine, which reduces preload through calcium channel blockade in the veins.
  4. Hydralazine, which reduces preload by direct relaxation of venous capacitance vessels.
Explanation: Nitroglycerin is a vasodilator that, particularly at lower doses, has a more pronounced effect on veins than on arteries. This venodilation increases venous capacitance, reduces venous return to the heart, and thereby decreases preload (cardiac filling pressures). This effect is highly beneficial in acute pulmonary edema. In contrast, sodium nitroprusside is a balanced vasodilator, affecting both arteries (afterload) and veins (preload) more equally.
  • (B) Sodium nitroprusside is a balanced, not a selective, venodilator.
  • (C) Nicardipine is an arterial vasodilator and has minimal effect on preload.
  • (D) Hydralazine is primarily an arterial vasodilator and has minimal effect on preload.

Question 11

A 67-year-old male presents with crushing substernal chest pain. His ECG shows ST-segment elevation in the anterior leads, and his blood pressure is 185/105 mmHg. In addition to aspirin and preparation for percutaneous coronary intervention, which medication is most beneficial for managing his hypertension in this specific context?

  1. Intravenous nitroglycerin (correct answer)
  2. Intravenous hydralazine
  3. Intravenous fenoldopam
  4. Intravenous enalaprilat
Explanation: In a hypertensive emergency complicated by acute coronary syndrome (ACS), intravenous nitroglycerin is a first-line agent. It serves a dual purpose: it lowers blood pressure (primarily by reducing preload) and alleviates myocardial ischemia by dilating coronary arteries and reducing myocardial oxygen demand. Intravenous beta-blockers are also a cornerstone of therapy, but among the choices provided, nitroglycerin offers the most targeted benefit for both hypertension and ischemia.
  • (B) Hydralazine can cause reflex tachycardia, which would increase myocardial oxygen demand and potentially worsen ischemia.
  • (C) and (D) Fenoldopam and enalaprilat would lower blood pressure but lack the direct anti-ischemic effects of nitroglycerin.

Question 12

A 32-year-old woman at 34 weeks gestation presents with a blood pressure of 170/115 mmHg, proteinuria, a severe headache, and visual disturbances. During evaluation, she has a generalized tonic-clonic seizure. In addition to magnesium sulfate for seizure control, which intravenous medication is a first-line agent for controlling her severe hypertension?

  1. Enalaprilat
  2. Sodium nitroprusside
  3. Labetalol (correct answer)
  4. Amlodipine
Explanation: This patient has eclampsia. The management of severe hypertension in pregnancy and preeclampsia/eclampsia involves agents that are safe for both the mother and fetus. Intravenous labetalol and intravenous hydralazine are considered first-line agents. Oral nifedipine is also an option.
  • (A) Enalaprilat is an ACE inhibitor, which is contraindicated in pregnancy due to teratogenicity.
  • (B) Sodium nitroprusside is generally avoided due to the risk of fetal cyanide toxicity and is only used in refractory cases for a short duration.
  • (D) Intravenous amlodipine is not available for use; while oral calcium channel blockers like nifedipine are used, IV labetalol is a preferred first-line parenteral agent in this emergent situation.

Question 13

A 50-year-old patient presents with a blood pressure of 230/135 mmHg. Which of the following clinical findings would most definitively classify this presentation as a hypertensive emergency rather than a hypertensive urgency?

  1. A bilateral, throbbing headache and significant anxiety.
  2. A documented history of non-adherence to antihypertensive medications.
  3. The presence of flame hemorrhages and papilledema on funduscopic exam. (correct answer)
  4. Trace pedal edema and a reported history of high blood pressure readings.
Explanation: The critical distinction between hypertensive urgency and emergency is the presence of acute, ongoing target-organ damage in an emergency. Papilledema (swelling of the optic disc due to increased intracranial pressure) and flame hemorrhages are signs of severe (Grade IV) hypertensive retinopathy, which is a clear indicator of acute end-organ damage (hypertensive encephalopathy). This finding mandates immediate parenteral treatment.
  • (A) Headache and anxiety are common with severe hypertension but are non-specific and do not, by themselves, constitute end-organ damage.
  • (B) Non-adherence is a common cause of severe hypertension but is not a clinical finding of organ damage.
  • (D) Trace pedal edema is usually a sign of a chronic condition (like heart failure or kidney disease) rather than acute damage.

Question 14

A 62-year-old man is seen in an urgent care clinic with a blood pressure of 190/110 mmHg. He denies chest pain, dyspnea, or any neurologic symptoms. The physical exam is negative for signs of acute target organ damage. The decision is made to treat his hypertensive urgency. Which of the following is the most suitable oral agent for initiating therapy in this setting?

  1. Nifedipine extended-release
  2. Minoxidil
  3. Hydralazine
  4. Clonidine (correct answer)
Explanation: When you encounter a patient with hypertensive urgency (severely elevated blood pressure without acute end-organ damage), the key principle is achieving gradual, controlled blood pressure reduction over hours to days. Rapid reduction can cause cerebral, cardiac, or renal ischemia due to impaired autoregulation in chronically hypertensive patients. Clonidine (D) is the best choice here because it's a centrally-acting alpha-2 agonist that provides predictable, gradual blood pressure reduction without precipitous drops. It reduces sympathetic outflow from the brain, leading to decreased heart rate and peripheral vascular resistance. This makes it ideal for hypertensive urgency where you want steady, controllable reduction. Nifedipine extended-release (A) might seem logical as a calcium channel blocker, but immediate-release nifedipine is contraindicated in hypertensive urgency due to unpredictable, potentially severe hypotension. Even extended-release formulations can cause excessive reduction in some patients. Minoxidil (B) is a potent direct vasodilator typically reserved for refractory hypertension. It causes rapid, profound blood pressure drops and significant reflex tachycardia, making it inappropriate for acute settings. Hydralazine (C) is also a direct vasodilator that can cause unpredictable, precipitous blood pressure drops. Its erratic absorption and effect make it unsuitable for controlled reduction in hypertensive urgency. Study tip: Remember the "go low and slow" principle for hypertensive urgency. Look for agents that provide gradual, predictable reduction rather than powerful vasodilators that might drop pressure too quickly.

Question 15

A 72-year-old female is diagnosed with hypertensive urgency, with a blood pressure of 205/110 mmHg and no evidence of acute end-organ damage. What is the primary therapeutic objective for this patient?

  1. Achieve a blood pressure of less than 140/90 mmHg within one hour using intravenous agents.
  2. Lower the mean arterial pressure by at least 25% within the first hour to prevent progression to emergency.
  3. Prescribe or adjust an oral antihypertensive regimen to achieve gradual blood pressure reduction over 24 to 48 hours. (correct answer)
  4. Admit the patient for cardiac monitoring and initiate an oral loading dose of amiodarone for rate control.
Explanation: In hypertensive urgency, there is no acute end-organ damage, so there is no need for rapid, aggressive blood pressure reduction. In fact, lowering the blood pressure too quickly can cause hypoperfusion and ischemia. The appropriate goal is to lower the blood pressure gradually over 24 to 48 hours, typically by initiating or adjusting oral antihypertensive medications and ensuring close outpatient follow-up.
  • (A) and (B) These describe the management goals for a hypertensive emergency and would be inappropriate and potentially harmful in a case of urgency.
  • (D) Amiodarone is an antiarrhythmic drug and is not indicated for the management of hypertension.

Question 16

A 68-year-old male with a history of poorly controlled hypertension presents for a routine check-up. He is asymptomatic. His blood pressure is 200/115 mmHg. Physical examination, including a funduscopic and neurologic exam, is unremarkable. Serum creatinine is at his baseline of 1.2 mg/dL. What is the most appropriate next step in management?

  1. Reinstitute and intensify his oral antihypertensive regimen and arrange for close follow-up within a few days. (correct answer)
  2. Administer a single dose of oral clonidine 0.2 mg and observe for 3-4 hours before discharge.
  3. Admit the patient for an intravenous infusion of nicardipine to lower the mean arterial pressure by 20% over the first hour.
  4. Administer a dose of immediate-release sublingual nifedipine and recheck blood pressure in 30 minutes.
Explanation: This patient presents with hypertensive urgency: severely elevated blood pressure without signs or symptoms of acute, ongoing target-organ damage. The goal is to lower blood pressure gradually over 24-48 hours. The most appropriate management is to adjust the patient's long-term oral medication regimen and ensure close follow-up. Rapid reduction in blood pressure is not necessary and can be harmful, potentially causing ischemia.
  • (B) While a single dose of an oral agent like clonidine can be used, the primary goal is establishing a sustainable long-term regimen, not just temporary reduction. This option is less optimal than a comprehensive medication adjustment.
  • (C) Intravenous therapy is reserved for hypertensive emergencies, where there is evidence of acute target-organ damage. This would be overly aggressive and potentially dangerous.
  • (D) Immediate-release nifedipine (sublingual or oral) is contraindicated due to its potential to cause a precipitous and unpredictable drop in blood pressure, which can lead to cerebral or myocardial ischemia.

Question 17

A 55-year-old man presents to the emergency department with a sudden onset of "tearing" chest pain radiating to his back. His blood pressure is 210/120 mmHg and heart rate is 115 bpm. Aortic dissection is suspected. What is the most critical initial pharmacotherapeutic goal?

  1. Rapidly decrease systolic blood pressure to <140 mmHg using an intravenous dihydropyridine calcium channel blocker as monotherapy.
  2. Immediately reduce both heart rate to <60 bpm and systolic blood pressure to <120 mmHg, typically with an IV beta-blocker and a vasodilator. (correct answer)
  3. Administer intravenous nitroglycerin to reduce preload and alleviate chest pain while preparing for surgical consultation.
  4. Prioritize heart rate control with an IV beta-blocker, followed by gradual blood pressure reduction over 24-48 hours with oral agents.
Explanation: In a suspected aortic dissection, the primary goals are to rapidly reduce both blood pressure and the rate of rise of systolic pressure (dP/dt), which is related to heart rate. The target is a heart rate <60 bpm and a systolic blood pressure of 100-120 mmHg, achieved within minutes. This is typically accomplished with an IV beta-blocker (e.g., esmolol) to control heart rate and dP/dt, followed by or co-administered with a vasodilator (e.g., sodium nitroprusside or clevidipine) to control blood pressure. A vasodilator alone would cause reflex tachycardia, increasing dP/dt and worsening the dissection.
  • (A) A calcium channel blocker alone would not control heart rate and could cause harmful reflex tachycardia.
  • (C) While nitroglycerin may be used for pain, it is not the primary agent for hemodynamic control in dissection.
  • (D) Blood pressure reduction must be immediate and aggressive, not gradual over days.

Question 18

A 32-year-old woman at 34 weeks gestation presents with a blood pressure of 170/115 mmHg, proteinuria, a severe headache, and visual disturbances. During evaluation, she has a generalized tonic-clonic seizure. In addition to magnesium sulfate for seizure control, which intravenous medication is a first-line agent for controlling her severe hypertension?

  1. Enalaprilat
  2. Sodium nitroprusside
  3. Labetalol (correct answer)
  4. Amlodipine
Explanation: This patient has eclampsia. The management of severe hypertension in pregnancy and preeclampsia/eclampsia involves agents that are safe for both the mother and fetus. Intravenous labetalol and intravenous hydralazine are considered first-line agents. Oral nifedipine is also an option.
  • (A) Enalaprilat is an ACE inhibitor, which is contraindicated in pregnancy due to teratogenicity.
  • (B) Sodium nitroprusside is generally avoided due to the risk of fetal cyanide toxicity and is only used in refractory cases for a short duration.
  • (D) Intravenous amlodipine is not available for use; while oral calcium channel blockers like nifedipine are used, IV labetalol is a preferred first-line parenteral agent in this emergent situation.

Question 19

A 48-year-old patient with refractory hypertensive emergency has been on a continuous infusion of sodium nitroprusside at a high dose for 48 hours. The patient becomes increasingly confused and develops an anion gap metabolic acidosis. Which of the following is the most likely cause of these findings?

  1. Thiocyanate accumulation leading to neurotoxicity.
  2. Cyanide toxicity from nitroprusside metabolism. (correct answer)
  3. Methemoglobinemia induced by the nitric oxide donor.
  4. Excessive vasodilation causing cerebral hypoperfusion.
Explanation: Sodium nitroprusside is metabolized to nitric oxide and five cyanide ions. The cyanide is then metabolized in the liver to the less toxic thiocyanate, which is cleared by the kidneys. With prolonged or high-dose infusions, or in patients with renal/hepatic impairment, cyanide can accumulate. Cyanide toxicity inhibits cellular respiration, leading to lactic acidosis (an anion gap metabolic acidosis), altered mental status, and seizures.
  • (A) Thiocyanate toxicity can occur, especially with renal impairment, but typically presents with psychosis, confusion, and weakness over a longer period. The acute metabolic acidosis is more characteristic of cyanide.
  • (C) Methemoglobinemia is a rare complication of nitroprusside.
  • (D) While hypoperfusion is a risk with any potent vasodilator, the specific combination of confusion and anion gap metabolic acidosis strongly points to a metabolic poison like cyanide.

Question 20

A 28-year-old man is brought to the emergency department with agitation, diaphoresis, mydriasis, and chest pain after using cocaine. His blood pressure is 220/130 mmHg and heart rate is 140 bpm. Which medication, if given as monotherapy, could paradoxically worsen hypertension and coronary vasoconstriction?

  1. Phentolamine
  2. Labetalol
  3. Propranolol (correct answer)
  4. Diazepam
Explanation: Cocaine causes a massive release of catecholamines, leading to intense stimulation of both alpha- and beta-adrenergic receptors. Administering a non-selective beta-blocker without alpha-blocking properties, such as propranolol, blocks the beta-2 receptor-mediated vasodilation. This leaves the alpha-1 receptor-mediated vasoconstriction unopposed, which can lead to a paradoxical rise in blood pressure and worsening coronary vasoconstriction.
  • (A) Phentolamine is an alpha-blocker and would be beneficial.
  • (B) Labetalol has both alpha- and beta-blocking properties, which makes it a safer option than a pure beta-blocker, although benzodiazepines are typically first-line.
  • (D) Diazepam, a benzodiazepine, is a first-line treatment for sympathomimetic toxicity, as it reduces central sympathetic outflow.