MED 9408 · Vasodilators · Independent study

Explain the mechanism.
Apply it to the patient.

Choose an answer before reading the explanation. Then explain why the other choices do not fit. Use the framework questions to connect the pharmacology, and the clinical vignettes to apply it.

Target → Action → Tissue effect → Body response → Uses and outcomes → Safety → PharmacokineticsConnect the steps that explain the response. A plausible mechanism alone does not establish a clinical outcome benefit.

Topic

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Framework practice

Question 1

A venodilator is given while blood volume is initially unchanged. The veins can now hold more blood at a given pressure.

Which change most directly explains a fall in ventricular filling?

Reduced ventricular contractility
Increased venous capacitance
Reduced circulating blood volume
Increased resistance to ventricular ejection

Answer and explanations

Best answer: B.

Reduced ventricular contractility
Venous dilation changes the distribution of blood. A decrease in intrinsic myocardial contractility is not required.
Increased venous capacitance
A larger venous reservoir reduces the blood returning to the heart and can lower ventricular filling pressure.
Reduced circulating blood volume
Redistribution can occur before any fluid leaves the body. Venodilation is not equivalent to diuresis.
Increased resistance to ventricular ejection
Greater ejection resistance would increase afterload. It does not explain the primary venous effect.

Question 2

An afterload-sensitive failing left ventricle ejects against a high systemic resistance. A vasodilator reduces that resistance without directly increasing contractility.

Which immediate ventricular change is most consistent with improved forward flow?

Increased end-systolic volume at unchanged end-diastolic volume
Increased calcium-dependent force generation in each myocyte
Reduced end-systolic volume with increased stroke volume
Increased pulmonary venous pressure

Answer and explanations

Best answer: C.

Increased end-systolic volume at unchanged end-diastolic volume
More blood left after systole would reduce stroke volume if end-diastolic volume remained unchanged.
Increased calcium-dependent force generation in each myocyte
This describes positive inotropy. The question specifies improvement from unloading rather than increased intrinsic contractility.
Reduced end-systolic volume with increased stroke volume
Lower ejection load allows more complete emptying. Stroke volume can rise because less blood remains after systole.
Increased pulmonary venous pressure
Higher pulmonary venous pressure worsens congestion; it is not the explanation for improved ejection.

Question 3

Nitric oxide reaches a vascular smooth-muscle cell and initiates the signaling pathway illustrated in the lecture.

Which sequence correctly connects its target to relaxation?

sGC activation → cGMP increase → PKG signaling → reduced myosin activation
Adenylyl cyclase activation → cAMP increase → direct actin destruction
PDE-5 activation → cGMP increase → calcium influx
NAT2 inhibition → acetylation decrease → membrane hyperpolarization

Answer and explanations

Best answer: A.

sGC activation → cGMP increase → PKG signaling → reduced myosin activation
NO activates soluble guanylyl cyclase. cGMP-dependent signaling reduces the calcium/myosin activation that maintains tone.
Adenylyl cyclase activation → cAMP increase → direct actin destruction
This substitutes the cAMP enzyme for sGC and incorrectly attributes relaxation to destruction of contractile proteins.
PDE-5 activation → cGMP increase → calcium influx
PDE-5 degrades cGMP; activating it would not increase cGMP. Increased calcium entry generally favors contraction.
NAT2 inhibition → acetylation decrease → membrane hyperpolarization
NAT2 concerns hydralazine metabolism. It is not the target that transduces the NO signal.

Question 4

Isosorbide dinitrate and isosorbide mononitrate can both be used for angina prevention, but their disposition after an oral dose differs.

Which statement best explains the more predictable oral availability of isosorbide mononitrate?

It acts only in the gastrointestinal tract
It directly stimulates sGC without bioactivation
It undergoes much less first-pass loss than isosorbide dinitrate
It cannot produce any active vascular species

Answer and explanations

Best answer: C.

It acts only in the gastrointestinal tract
Its antianginal effect requires systemic vascular exposure; a local gastrointestinal effect would not explain that benefit.
It directly stimulates sGC without bioactivation
High oral availability does not mean direct receptor action. ISMN remains an organic nitrate requiring bioactivation.
It undergoes much less first-pass loss than isosorbide dinitrate
ISDN has substantial, variable first-pass metabolism and forms active mononitrates. ISMN has high oral availability with little first-pass loss.
It cannot produce any active vascular species
ISMN is pharmacologically active after bioactivation. Failure to generate an active signal would not explain preventive efficacy.

Question 5

A learner reasons that isosorbide preparations should not develop tolerance because their activation differs from the ALDH2-dependent pathway emphasized for nitroglycerin.

What is the best correction to this reasoning?

Different activation pathways can still encounter vascular adaptation and counterregulation
Isosorbide preparations are simply converted into nitroglycerin
Tolerance proves that every organic nitrate uses the same activation enzyme
Tolerance occurs only when the prescribed nitrate dose is reduced

Answer and explanations

Best answer: A.

Different activation pathways can still encounter vascular adaptation and counterregulation
ALDH2 impairment is one proposed contributor to NTG tolerance. Shared downstream adaptation, neurohormonal responses and volume expansion can also oppose isosorbide effects.
Isosorbide preparations are simply converted into nitroglycerin
ISDN forms mononitrate metabolites; neither ISDN nor ISMN must become NTG to act.
Tolerance proves that every organic nitrate uses the same activation enzyme
A shared clinical phenomenon does not establish an identical upstream biochemical pathway.
Tolerance occurs only when the prescribed nitrate dose is reduced
Tolerance means the response diminishes during maintained exposure. A dose reduction is not required.

Question 6

A transdermal nitroglycerin regimen is designed to limit tolerance while providing coverage during the patient’s usual period of exertion.

Which schedule reflects the usual U.S. patch-label approach discussed in the lecture?

Keep each patch on continuously for 24 hours
Replace the patch every hour with no gap
Wear the patch for 10 minutes before symptoms occur
Wear it for 12–14 hours, followed by 10–12 hours off

Answer and explanations

Best answer: D.

Keep each patch on continuously for 24 hours
Continuous exposure promotes tolerance, even if the patch continues to deliver drug.
Replace the patch every hour with no gap
Frequent replacement does not create the low-exposure interval needed to limit tolerance.
Wear the patch for 10 minutes before symptoms occur
The transdermal preparation provides sustained prevention; it is not the rapid sublingual rescue formulation.
Wear it for 12–14 hours, followed by 10–12 hours off
This daily interruption helps preserve the on-period response. The gap reduces nitrate coverage, so timing matters; oral schedules are formulation-specific.

Question 7

A PDE-5 inhibitor enhances a cGMP-mediated vascular response without donating nitric oxide.

Which process does it directly inhibit?

Formation of cGMP from GTP
Degradation of cGMP
Formation of nitric oxide from a nitrate
Acetylation of hydralazine

Answer and explanations

Best answer: B.

Formation of cGMP from GTP
Blocking cGMP synthesis would oppose the desired effect. sGC is involved in generating cGMP.
Degradation of cGMP
PDE-5 inhibition slows cGMP breakdown and prolongs an existing cGMP signal.
Formation of nitric oxide from a nitrate
Bioactivation is an upstream process. PDE-5 acts on the second messenger after it has been formed.
Acetylation of hydralazine
Acetylation concerns hydralazine exposure and NAT2; it does not explain PDE-5 inhibition.

Question 8

Nitroglycerin and sildenafil act at different control points in the same signaling pathway.

Why can their combination produce severe hypotension?

Both directly block cardiac β₁ receptors
Sildenafil prevents nitroglycerin absorption
Nitroglycerin accelerates cGMP breakdown
One increases cGMP formation while the other limits its breakdown

Answer and explanations

Best answer: D.

Both directly block cardiac β₁ receptors
Neither drug’s principal action is β₁ blockade. The interaction is predominantly excessive vascular relaxation.
Sildenafil prevents nitroglycerin absorption
Reduced absorption would tend to reduce nitrate activity. It does not explain the dangerous enhancement.
Nitroglycerin accelerates cGMP breakdown
Nitroglycerin-derived signaling promotes cGMP formation; it does not accelerate its degradation.
One increases cGMP formation while the other limits its breakdown
The two effects amplify cGMP-mediated dilation. Nitrate use with a PDE-5 inhibitor is contraindicated.

Question 9

Several drugs share PDE-5 inhibition, but U.S. indications and dosing regimens differ among products.

Which comparison is accurate?

Sildenafil and tadalafil have PAH regimens; an erectile-dysfunction regimen is not interchangeable with them
Every PDE-5 inhibitor is FDA-approved for PAH
A PAH regimen is intended only for use immediately before sexual activity
PDE-5 inhibitors and riociguat can routinely be combined because their targets differ

Answer and explanations

Best answer: A.

Sildenafil and tadalafil have PAH regimens; an erectile-dysfunction regimen is not interchangeable with them
The same molecular target can support different indications and exposure schedules. Product and indication must be specified.
Every PDE-5 inhibitor is FDA-approved for PAH
Vardenafil and avanafil do not acquire a PAH indication simply by sharing the mechanism.
A PAH regimen is intended only for use immediately before sexual activity
This describes on-demand erectile-dysfunction treatment, not scheduled therapy for pulmonary vascular disease.
PDE-5 inhibitors and riociguat can routinely be combined because their targets differ
Different control points can still cause excessive hypotension. PDE-5 inhibitors are contraindicated with riociguat.

Question 10

Nitroprusside dilates both venous and arterial vessels in a patient with elevated filling pressure and an afterload-sensitive failing left ventricle.

Which paired response best captures the therapeutic goal?

Higher filling pressure and lower forward output
Higher intrinsic contractility and higher myocardial oxygen demand
Lower filling pressure and greater forward output
Lower filling pressure with an obligatory rise in systemic blood pressure

Answer and explanations

Best answer: C.

Higher filling pressure and lower forward output
Those changes describe worsening congestion and perfusion rather than successful unloading.
Higher intrinsic contractility and higher myocardial oxygen demand
Nitroprusside is a vasodilator, not a direct positive inotrope. More forward flow need not require stronger intrinsic contraction.
Lower filling pressure and greater forward output
Venous unloading and improved emptying can relieve pulmonary congestion while reduced afterload improves ejection. The response depends on the patient’s loading conditions.
Lower filling pressure with an obligatory rise in systemic blood pressure
Blood pressure depends on both output and resistance. An increase in output does not require an increase in pressure.

Question 11

Two toxicities associated with nitroprusside can impair oxygen-dependent function despite an adequate arterial oxygen tension.

Which distinction between cyanide toxicity and methemoglobinemia is correct?

Both are caused solely by reduced renal elimination of thiocyanate
Cyanide impairs cellular oxygen use; methemoglobin impairs effective oxygen carriage
Cyanide only reduces dissolved oxygen in plasma
Methemoglobinemia is the same as an acute fall in hemoglobin concentration

Answer and explanations

Best answer: B.

Both are caused solely by reduced renal elimination of thiocyanate
Thiocyanate accumulation is a separate toxicity. It does not explain either mechanism named here.
Cyanide impairs cellular oxygen use; methemoglobin impairs effective oxygen carriage
Cyanide inhibits complex IV. Oxidation of hemoglobin iron reduces useful oxygen transport; arterial oxygen tension alone cannot exclude either problem.
Cyanide only reduces dissolved oxygen in plasma
The key defect is mitochondrial use of oxygen, not simply a low dissolved oxygen measurement.
Methemoglobinemia is the same as an acute fall in hemoglobin concentration
The problem is altered hemoglobin function. Hemoglobin concentration need not fall.

Question 12

During nitroprusside metabolism, cyanide is converted into thiocyanate. A patient’s renal function subsequently declines.

Which exposure-related concern becomes especially important during a prolonged infusion?

Rapid loss of all thiocyanate through the lungs
Immediate loss of nitroprusside’s vasodilator action
Conversion of thiocyanate into an active antihypertensive metabolite
Thiocyanate accumulation with neurologic toxicity

Answer and explanations

Best answer: D.

Rapid loss of all thiocyanate through the lungs
Thiocyanate elimination depends substantially on the kidneys; pulmonary elimination does not prevent accumulation.
Immediate loss of nitroprusside’s vasodilator action
Renal impairment does not reliably switch off the direct vasodilator response.
Conversion of thiocyanate into an active antihypertensive metabolite
The teaching concern is accumulation of a toxic metabolite, not prolonged therapeutic vasodilation from thiocyanate.
Thiocyanate accumulation with neurologic toxicity
Longer exposure and reduced renal clearance favor accumulation. Tinnitus and altered mental status are important clues.

Question 13

Riociguat and vericiguat stimulate soluble guanylyl cyclase. Nesiritide also increases cGMP but acts through a different receptor system.

Which target comparison is correct?

sGC stimulators act on the soluble enzyme; nesiritide acts through NPR-A membrane guanylyl cyclase
All three drugs directly inhibit PDE-5
Nesiritide activates a β₁ receptor, while the other two release norepinephrine
Riociguat and vericiguat require conversion into organic nitrates

Answer and explanations

Best answer: A.

sGC stimulators act on the soluble enzyme; nesiritide acts through NPR-A membrane guanylyl cyclase
These pathways converge on cGMP but differ at the target. Shared second-messenger signaling does not make the drugs clinically interchangeable.
All three drugs directly inhibit PDE-5
PDE-5 inhibitors limit cGMP breakdown. These drugs instead promote cGMP generation through different targets.
Nesiritide activates a β₁ receptor, while the other two release norepinephrine
This replaces the cGMP pathways with adrenergic mechanisms that do not describe these drugs.
Riociguat and vericiguat require conversion into organic nitrates
They stimulate sGC without needing conversion into nitrate drugs. They also enhance the enzyme’s response to NO.

Question 14

VICTORIA evaluated vericiguat added to background therapy in symptomatic heart failure with reduced ejection fraction after recent worsening.

Which statement best preserves the meaning of its outcome evidence?

Vericiguat replaces foundational HFrEF treatment
Vericiguat has the same CTEPH indication as riociguat
The CV-death/HF-hospitalization composite was reduced with add-on treatment
All patients with dyspnea benefit regardless of EF or recent course

Answer and explanations

Best answer: C.

Vericiguat replaces foundational HFrEF treatment
The trial tested additional therapy. Its benefit does not establish replacement of foundational treatment.
Vericiguat has the same CTEPH indication as riociguat
Clinical indications are agent-specific. A shared sGC target is not evidence for interchangeable indications.
The CV-death/HF-hospitalization composite was reduced with add-on treatment
This states the tested comparison and endpoint. A separate mortality benefit was not established.
All patients with dyspnea benefit regardless of EF or recent course
The studied population had symptomatic chronic HF, EF below 45%, and recent worsening. Generalizing to all dyspnea is unsupported.

Question 15

Early nesiritide trials showed lower filling pressures. ASCEND-HF subsequently examined clinical benefit in a much larger acute heart-failure population.

Which conclusion best illustrates the lesson of this sequence?

Any reduction in wedge pressure establishes a survival benefit
Improved hemodynamics did not establish fewer deaths or HF readmissions
ASCEND-HF confirmed a large increase in mortality
Failure to reduce mortality proves that nesiritide cannot lower filling pressure

Answer and explanations

Best answer: B.

Any reduction in wedge pressure establishes a survival benefit
A hemodynamic surrogate cannot establish a mortality effect without outcome evidence.
Improved hemodynamics did not establish fewer deaths or HF readmissions
ASCEND-HF did not show a significant 30-day death/HF-readmission benefit and found more hypotension. Useful physiology and clinical outcomes are different questions.
ASCEND-HF confirmed a large increase in mortality
The trial did not confirm a significant mortality increase. The earlier safety signal required reassessment rather than automatic acceptance.
Failure to reduce mortality proves that nesiritide cannot lower filling pressure
A drug can change a physiological measurement without improving a later clinical endpoint. These findings are not contradictory.

Question 16

Inhaled nitric oxide reaches ventilated alveoli and adjacent pulmonary vessels before entering the blood.

Which pair of properties best explains its pulmonary selectivity?

Selective delivery to unventilated alveoli and slow renal clearance
A pulmonary-only sGC receptor and irreversible receptor binding
Hepatic first-pass activation and systemic accumulation
Local inhaled delivery and rapid scavenging by hemoglobin

Answer and explanations

Best answer: D.

Selective delivery to unventilated alveoli and slow renal clearance
Inhaled gas preferentially reaches ventilated regions. Slow renal elimination does not explain localization of active NO.
A pulmonary-only sGC receptor and irreversible receptor binding
sGC is not confined to pulmonary vessels. Delivery and rapid inactivation, rather than a unique receptor, explain selectivity.
Hepatic first-pass activation and systemic accumulation
An inhaled drug reaches the pulmonary interface directly; hepatic first pass is not the relevant mechanism.
Local inhaled delivery and rapid scavenging by hemoglobin
NO acts near ventilated alveoli, then reacts rapidly in blood. Little active NO remains available for distant systemic vessels.

Question 17

A clinician distinguishes the desired effect of inhaled NO from hazards that arise in blood, the delivery circuit and withdrawal.

Which set of concerns belongs to inhaled NO therapy?

NAT2-related lupus, hypertrichosis and thiocyanate accumulation
PDE-5 inhibition, sodium-channel blockade and β₁ stimulation
Methemoglobinemia, NO₂ airway injury and rebound pulmonary hypertension
An obligatory long-term survival benefit and no withdrawal effect

Answer and explanations

Best answer: C.

NAT2-related lupus, hypertrichosis and thiocyanate accumulation
These point to hydralazine, minoxidil and nitroprusside, respectively; they are not the characteristic inhaled-NO safety set.
PDE-5 inhibition, sodium-channel blockade and β₁ stimulation
These are different drug actions rather than the relevant hazards of inhaled NO.
Methemoglobinemia, NO₂ airway injury and rebound pulmonary hypertension
Monitor oxygen carriage and gas delivery, and withdraw gradually. Pulmonary selectivity does not eliminate toxicity.
An obligatory long-term survival benefit and no withdrawal effect
An oxygenation response is not a universal survival claim, and abrupt withdrawal can worsen pulmonary vascular status.

Question 18

Endothelin receptor antagonists reduce endothelin-mediated vascular tone, but receptor selectivity and therapeutic use vary by agent.

Which pairing is correct?

Ambrisentan: relatively selective ETA blockade; bosentan and macitentan: dual ETA/ETB blockade
Ambrisentan: PDE-5 inhibition; bosentan: direct NO donation
Every endothelin antagonist: the same indication and monitoring schedule
Aprocitentan: an inhaled rescue treatment for neonatal hypoxemia

Answer and explanations

Best answer: A.

Ambrisentan: relatively selective ETA blockade; bosentan and macitentan: dual ETA/ETB blockade
These drugs treat PAH through endothelin antagonism. Aprocitentan is also dual but has a U.S. add-on systemic-hypertension indication.
Ambrisentan: PDE-5 inhibition; bosentan: direct NO donation
Neither pairing describes endothelin receptor antagonism.
Every endothelin antagonist: the same indication and monitoring schedule
Mechanistic overlap does not erase agent-specific indications or differences such as bosentan’s liver monitoring.
Aprocitentan: an inhaled rescue treatment for neonatal hypoxemia
Aprocitentan is an oral antihypertensive endothelin antagonist, not inhaled nitric oxide.

Question 19

Patients receiving the same oral hydralazine dose can have substantially different drug exposure. NAT2 genotype influences acetylator phenotype.

Which consequence follows most directly from slower acetylation?

A different molecular target in the vessel wall
Lower parent-drug exposure requiring a larger dose in every case
Elimination of all variability in blood-pressure response
Greater parent-drug exposure and potentially lower dose requirements

Answer and explanations

Best answer: D.

A different molecular target in the vessel wall
The inherited difference concerns metabolism. It does not replace hydralazine’s vascular site of action.
Lower parent-drug exposure requiring a larger dose in every case
Slower acetylation generally increases parent-drug exposure. Dose requirements must still be individualized.
Elimination of all variability in blood-pressure response
Genotype explains part of the variation, not every influence on exposure, adherence or hemodynamics.
Greater parent-drug exposure and potentially lower dose requirements
Inherited metabolism can change the BP response to a given oral dose. Greater exposure also contributes to susceptibility to adverse effects.

Question 20

Hydralazine can cause tachycardia and fluid retention, but also drug-induced lupus and peripheral neuropathy.

Which interpretation separates these mechanisms correctly?

All four effects are manifestations of the same baroreflex
Tachycardia and retention reflect compensation; lupus and neuropathy need distinct explanations
A positive ANA alone confirms symptomatic hydralazine-induced lupus
U.S. labeling gives an exact prospective incidence of hydralazine neuropathy

Answer and explanations

Best answer: B.

All four effects are manifestations of the same baroreflex
The baroreflex explains tachycardia but does not explain lupus or the possible vitamin-B₆-related neuropathy.
Tachycardia and retention reflect compensation; lupus and neuropathy need distinct explanations
Lupus is an immune-mediated toxicity influenced by exposure and susceptibility. The label links neuropathic symptoms to a possible antipyridoxine effect.
A positive ANA alone confirms symptomatic hydralazine-induced lupus
ANA positivity alone is not the clinical syndrome; symptoms and clinical assessment matter.
U.S. labeling gives an exact prospective incidence of hydralazine neuropathy
U.S. labeling does not provide a dependable numerical frequency. An unsupported percentage should not be invented.

Question 21

V-HeFT I, V-HeFT II, retrospective racial subgroup analyses and A-HeFT are presented as a sequence of evidence about hydralazine–ISDN.

Which interpretation best respects their different questions?

Preserve each comparator, population and endpoint; subgroup findings informed a later prospective trial
A-HeFT established that hydralazine–ISDN should replace enalapril in every patient
Different subgroup P values prove an inherited difference in NO biology
All trials can be pooled as if they compared the same treatments on identical background therapy

Answer and explanations

Best answer: A.

Preserve each comparator, population and endpoint; subgroup findings informed a later prospective trial
V-HeFT I compared the combination with placebo, V-HeFT II with enalapril, and A-HeFT tested add-on treatment in self-identified Black patients. Separate subgroup P values are not an interaction test.
A-HeFT established that hydralazine–ISDN should replace enalapril in every patient
A-HeFT evaluated addition to background therapy in a defined population, not universal replacement of renin–angiotensin therapy.
Different subgroup P values prove an inherited difference in NO biology
Statistical significance within one subgroup but not another does not establish an interaction, and self-identified race is not a genotype assay.
All trials can be pooled as if they compared the same treatments on identical background therapy
Comparators and background treatments changed. Ignoring those differences obscures what each trial can support.

Question 22

Minoxidil is converted to an active sulfate metabolite in the pathway shown in the lecture.

Which sequence explains its direct arteriolar effect?

KATP closure → depolarization → reduced calcium entry
β₁ blockade → slower heart rate → venous dilation
KATP opening → hyperpolarization → reduced voltage-dependent calcium entry
NPR-A activation → cGMP formation → renal nitrate clearance

Answer and explanations

Best answer: C.

KATP closure → depolarization → reduced calcium entry
Closing potassium channels tends to favor depolarization, which does not explain reduced voltage-dependent calcium entry.
β₁ blockade → slower heart rate → venous dilation
This describes neither the target nor the primary vascular effect of minoxidil.
KATP opening → hyperpolarization → reduced voltage-dependent calcium entry
The active metabolite opens ATP-sensitive potassium channels. Hyperpolarization reduces smooth-muscle activation and arteriolar tone.
NPR-A activation → cGMP formation → renal nitrate clearance
NPR-A is the natriuretic-peptide receptor pathway. It is not minoxidil’s mechanism.

Question 23

Minoxidil is used orally for reserved hypertension therapy and topically for scalp hair growth.

Which statement best connects route to clinical consequences?

The two routes always produce identical systemic exposure
Hair growth proves that cardiovascular adverse effects cannot occur
A topical regimen can be substituted for oral treatment of severe hypertension
Route changes exposure and purpose; oral use requires attention to systemic toxicity

Answer and explanations

Best answer: D.

The two routes always produce identical systemic exposure
Topical scalp use generally produces much lower systemic exposure. Formulation, dose and skin condition still matter.
Hair growth proves that cardiovascular adverse effects cannot occur
A hair-growth effect does not exclude systemic hemodynamic toxicity, especially with oral exposure.
A topical regimen can be substituted for oral treatment of severe hypertension
The exposure goals and regimens differ; topical scalp treatment is not systemic antihypertensive therapy.
Route changes exposure and purpose; oral use requires attention to systemic toxicity
Reflex tachycardia, fluid retention and pericardial toxicity are central concerns with oral antihypertensive use. Hypertrichosis connects the drug to its hair-growth application.

Question 24

Fenoldopam activates D₁ receptors and increases cAMP. Its renal vascular effects can be attractive during severe hypertension.

Which conclusion is most accurate?

An increase in renal blood flow establishes protection from dialysis or death
Its short IV action permits BP titration, but renal vasodilation does not prove renal outcome benefit
It is a dopamine-like β₁ inotrope at its usual therapeutic target
A β blocker is automatically paired with it exactly as with oral minoxidil

Answer and explanations

Best answer: B.

An increase in renal blood flow establishes protection from dialysis or death
Renal flow is a physiological measurement. Clinical renal protection requires outcome evidence.
Its short IV action permits BP titration, but renal vasodilation does not prove renal outcome benefit
Fenoldopam is an IV antihypertensive, not a proven kidney-protective therapy. Hypokalemia and increased intraocular pressure are relevant precautions.
It is a dopamine-like β₁ inotrope at its usual therapeutic target
Fenoldopam’s D₁-selective action differs from dopamine’s broader, concentration-dependent receptor effects.
A β blocker is automatically paired with it exactly as with oral minoxidil
Do not transfer minoxidil’s usual pairing indiscriminately. Fenoldopam labeling cautions that β-blocker coadministration can exaggerate hypotension.

Clinical vignettes

Question 1

A patient with a fixed coronary stenosis develops predictable chest discomfort when walking uphill. Sublingual nitroglycerin relieves the episode. The instructor asks how relief can occur without requiring a large increase in flow through the stenosis.

Which change best explains the benefit?

Increased heart rate at unchanged wall tension
Increased end-diastolic volume at unchanged ventricular pressure
Reduced ventricular filling and wall tension
Increased systemic vascular resistance
Increased intrinsic myocardial contractility

Answer and explanations

Best answer: C.

Increased heart rate at unchanged wall tension
A faster rate increases oxygen demand and shortens diastole; it does not explain the usual nitrate benefit.
Increased end-diastolic volume at unchanged ventricular pressure
Greater filling is not the expected nitrate response. Venous unloading reduces ventricular filling and wall tension.
Reduced ventricular filling and wall tension
Venous pooling lowers preload and wall tension, reducing oxygen demand despite the fixed supply limitation.
Increased systemic vascular resistance
A higher ejection load increases myocardial work rather than explaining symptom relief.
Increased intrinsic myocardial contractility
Stronger intrinsic contraction tends to increase oxygen demand. Direct positive inotropy is not the principal nitrate action.

Question 2

A patient with an inferior myocardial infarction has right ventricular involvement, low blood pressure, elevated jugular venous pressure and clear lungs. The team is concerned about giving a nitrate.

Which physiological change explains the concern?

Reduced coronary resistance with increased right ventricular oxygen demand
Reduced venous return to a preload-dependent right ventricle
Direct suppression of right ventricular calcium entry
Increased resistance opposing right ventricular ejection
Increased intravascular volume from immediate renal sodium retention

Answer and explanations

Best answer: B.

Reduced coronary resistance with increased right ventricular oxygen demand
Coronary dilation does not necessarily increase demand. Excessive unloading is the immediate concern in this preload-dependent state.
Reduced venous return to a preload-dependent right ventricle
Less filling can reduce right-sided output, left-sided filling and systemic pressure in this setting.
Direct suppression of right ventricular calcium entry
A direct negative inotropic calcium-channel effect is not the main nitrate mechanism.
Increased resistance opposing right ventricular ejection
Nitrates do not principally act by increasing right ventricular afterload.
Increased intravascular volume from immediate renal sodium retention
Retention can accompany longer-term compensation, but it does not explain the immediate danger from reduced filling.

Question 3

A patient prescribed sublingual nitroglycerin for angina reports taking sildenafil earlier the same day. The patient asks why the nitrate cannot simply be used as usual.

Which explanation best accounts for the interaction?

Reduced nitrate metabolism through inhibition of NAT2
Competitive displacement of nitroglycerin from cardiac β₁ receptors
Additive suppression of sinoatrial-node automaticity
Inhibition of the same enzyme that forms cGMP
Enhanced cGMP production combined with reduced cGMP breakdown

Answer and explanations

Best answer: E.

Reduced nitrate metabolism through inhibition of NAT2
NAT2 variation matters for hydralazine; it is not the basis of the nitrate–sildenafil interaction.
Competitive displacement of nitroglycerin from cardiac β₁ receptors
Nitroglycerin does not lower pressure by binding cardiac β₁ receptors.
Additive suppression of sinoatrial-node automaticity
Direct sinoatrial suppression is not the central action of either drug. Excessive vascular relaxation is the concern.
Inhibition of the same enzyme that forms cGMP
Sildenafil inhibits cGMP breakdown, not its formation. The drugs act at different control points.
Enhanced cGMP production combined with reduced cGMP breakdown
Amplified cGMP signaling can cause severe hypotension. Nitrates and PDE-5 inhibitors are a contraindicated combination.

Question 4

During a high-rate nitroprusside infusion, a patient develops confusion and a rising lactate. Arterial oxygen tension and measured methemoglobin are normal, and systemic pressure and cardiac output remain adequate. The team suspects impaired cellular oxygen use.

Which mechanism best explains this pattern?

Inhibition of mitochondrial complex IV by cyanide
Oxidation of hemoglobin iron to methemoglobin
Reduced tissue delivery from profound systemic hypotension
Reduced alveolar oxygen transfer
Renal accumulation of thiocyanate

Answer and explanations

Best answer: A.

Inhibition of mitochondrial complex IV by cyanide
The exposure and failure of oxygen use despite preserved delivery support cyanide toxicity. Suspected toxicity requires immediate action rather than waiting for a confirmatory level.
Oxidation of hemoglobin iron to methemoglobin
This would impair oxygen carriage, but measured methemoglobin is normal in the case.
Reduced tissue delivery from profound systemic hypotension
Excessive dilation can cause hypoperfusion, but maintained pressure and output make that less consistent with the stated pattern.
Reduced alveolar oxygen transfer
Adequate arterial oxygen tension argues against inadequate transfer as the main cause of the impaired cellular respiration.
Renal accumulation of thiocyanate
Thiocyanate mainly produces metabolite-related neurologic toxicity. Acute inhibition of mitochondrial oxygen use during high-rate exposure points to cyanide.

Question 5

A patient with advanced chronic kidney disease receives a prolonged nitroprusside infusion. Tinnitus and new confusion develop, raising concern about a renally eliminated metabolite.

Which substance is most likely accumulating?

Free nitric oxide
Cyanide
Methemoglobin
Thiocyanate
Unchanged nitroprusside

Answer and explanations

Best answer: D.

Free nitric oxide
Active NO is short-lived. It is not the renally cleared metabolite associated with prolonged-infusion neurotoxicity.
Cyanide
Cyanide is an important acute toxicity, especially when generation exceeds detoxification. The specified renally eliminated metabolite is thiocyanate.
Methemoglobin
This is altered hemoglobin with impaired oxygen transport, not the renal metabolite producing the described accumulation pattern.
Thiocyanate
Reduced renal clearance and prolonged exposure favor accumulation, with tinnitus and altered mental status as clues.
Unchanged nitroprusside
The parent drug has a rapid pharmacodynamic offset. The prolonged renal accumulation issue is its thiocyanate metabolite.

Question 6

An adult has persistent pulmonary hypertension after surgery for chronic thromboembolic disease. Specialist reassessment identifies a role for an oral sGC stimulator with a U.S. indication for this condition.

Which drug fits this clinical role?

Vericiguat
Aprocitentan
Riociguat
Nesiritide
Sildenafil

Answer and explanations

Best answer: C.

Vericiguat
Vericiguat is an sGC stimulator, but its U.S. indication is selected symptomatic chronic HF after worsening, not CTEPH.
Aprocitentan
Aprocitentan is an endothelin antagonist used as add-on therapy for inadequately controlled systemic hypertension.
Riociguat
Riociguat is indicated for inoperable or persistent/recurrent CTEPH after surgery. CTEPH is WHO group 4 pulmonary hypertension, distinct from group 1 PAH.
Nesiritide
Nesiritide acts through a membrane guanylyl-cyclase receptor and does not have this CTEPH indication.
Sildenafil
Sildenafil inhibits PDE-5 and has PAH regimens, but it is not the sGC stimulator with the specified CTEPH indication.

Question 7

A patient with symptomatic chronic HFrEF, an EF of 30% and a recent HF hospitalization remains symptomatic on tolerated foundational therapy. Vericiguat is being considered as an additional agent.

Which description most accurately states the evidence supporting this use?

A mortality reduction from substituting vericiguat for an ACE inhibitor
A reduction in the CV-death/HF-hospitalization composite with add-on treatment after recent worsening
A reduction in hospitalizations specifically in HF with preserved EF
An immediate reduction in mortality from an IV rescue infusion
A survival benefit inferred from a lower pulmonary wedge pressure alone

Answer and explanations

Best answer: B.

A mortality reduction from substituting vericiguat for an ACE inhibitor
VICTORIA did not test substitution for foundational renin–angiotensin treatment.
A reduction in the CV-death/HF-hospitalization composite with add-on treatment after recent worsening
This matches VICTORIA’s population, comparison and endpoint. A separate mortality benefit was not established.
A reduction in hospitalizations specifically in HF with preserved EF
The relevant trial studied symptomatic HF with EF below 45%, not a preserved-EF population.
An immediate reduction in mortality from an IV rescue infusion
Vericiguat is oral therapy; the trial did not study an IV rescue strategy.
A survival benefit inferred from a lower pulmonary wedge pressure alone
Clinical endpoint evidence supports the role; a pressure surrogate alone could not establish a survival claim.

Question 8

A self-identified Black patient has persistent NYHA class III HFrEF symptoms despite tolerated guideline-directed therapy. The team discusses adding hydralazine–isosorbide dinitrate and reviews A-HeFT.

Which explanation most appropriately supports the decision?

Evidence that an abnormal NO genotype was identified in each participant
Evidence that the combination was superior to enalapril as replacement therapy
Evidence limited to a lower wedge pressure, without clinical endpoints
Evidence from an exclusively asymptomatic left-ventricular-dysfunction population
Evidence of lower mortality and fewer first HF hospitalizations with add-on treatment in a similar enrolled population

Answer and explanations

Best answer: E.

Evidence that an abnormal NO genotype was identified in each participant
Trial enrollment used self-identified race, not an individual NO-pathway genotype test.
Evidence that the combination was superior to enalapril as replacement therapy
That is not A-HeFT’s comparison. V-HeFT II compared the combination with enalapril and favored enalapril for two-year survival.
Evidence limited to a lower wedge pressure, without clinical endpoints
A-HeFT assessed clinical outcomes, including mortality and HF hospitalization.
Evidence from an exclusively asymptomatic left-ventricular-dysfunction population
A-HeFT enrolled symptomatic HF patients. The clinical setting is part of interpreting its result.
Evidence of lower mortality and fewer first HF hospitalizations with add-on treatment in a similar enrolled population
This preserves the tested population and comparison. The combination supplements tolerated foundational treatment in the relevant clinical role.

Question 9

A 38-week neonate has hypoxic respiratory failure with echocardiographic evidence of pulmonary hypertension despite ventilatory support. Inhaled nitric oxide is added.

Which benefit is best supported for this U.S.-labeled setting?

Improved oxygenation and reduced need for ECMO
A reduction in mortality demonstrated independently of ECMO use
Correction of hypoxemia primarily through systemic arterial dilation
Sustained pulmonary benefit after a single brief inhalation
Improved oxygen carriage through increased hemoglobin synthesis

Answer and explanations

Best answer: A.

Improved oxygenation and reduced need for ECMO
This is the supported goal in term and near-term neonates with hypoxic respiratory failure and pulmonary hypertension.
A reduction in mortality demonstrated independently of ECMO use
A reduction in ECMO use should not be restated as a separately established mortality benefit.
Correction of hypoxemia primarily through systemic arterial dilation
The inhaled route directs activity to pulmonary vessels near ventilated alveoli.
Sustained pulmonary benefit after a single brief inhalation
The short-lived effect requires controlled delivery; it does not behave as a long-acting one-time dose.
Improved oxygen carriage through increased hemoglobin synthesis
The principal response is pulmonary vasodilation. NO can actually impair carriage through methemoglobin formation.

Question 10

A patient’s pulmonary pressures and oxygenation improve during inhaled NO therapy. After the delivery is abruptly interrupted, oxygenation deteriorates and pulmonary artery pressure rises.

Which explanation best fits the timing?

Methemoglobinemia newly triggered by stopping the gas
NO₂-induced airway injury from ongoing delivery
Pulmonary edema from increased flow into a poorly functioning left ventricle
Loss of systemic NO accumulation through renal excretion
Rebound pulmonary hypertension after sudden loss of vasodilator support

Answer and explanations

Best answer: E.

Methemoglobinemia newly triggered by stopping the gas
Methemoglobinemia can arise during exposure. A rapid pressure rise immediately after interruption more directly indicates withdrawal-related rebound.
NO₂-induced airway injury from ongoing delivery
NO₂ is a delivery-related hazard, but cessation followed by an abrupt pulmonary-pressure rise is more consistent with rebound.
Pulmonary edema from increased flow into a poorly functioning left ventricle
This can occur during treatment in LV dysfunction. It is less consistent with deterioration immediately on removing the vasodilator.
Loss of systemic NO accumulation through renal excretion
Active NO does not depend on prolonged systemic accumulation or renal removal for its offset.
Rebound pulmonary hypertension after sudden loss of vasodilator support
The timing and pressure rise support rebound. Discontinuation requires a controlled wean with monitoring.

Question 11

A patient with pulmonary arterial hypertension is starting bosentan. The clinician plans a laboratory test before treatment and monthly thereafter because of an agent-specific toxicity.

Which test is central to that monitoring plan?

Plasma thiocyanate
Serum potassium
Hemoglobin concentration
Liver aminotransferases
Serum creatinine

Answer and explanations

Best answer: D.

Plasma thiocyanate
This measures a nitroprusside metabolite; it does not assess bosentan hepatotoxicity.
Serum potassium
Potassium assessment can matter in clinical care, but it is not the required monthly hepatic screen described here.
Hemoglobin concentration
Anemia is also relevant with endothelin antagonists. Hemoglobin monitoring does not replace the specified baseline and monthly liver testing.
Liver aminotransferases
Bosentan can cause hepatotoxicity. U.S. labeling calls for aminotransferases before treatment and monthly thereafter.
Serum creatinine
Renal function may need assessment, but creatinine does not provide the required screen for hepatocellular injury.

Question 12

Two patients with similar adherence and organ function receive the same oral hydralazine dose. One has substantially higher measured parent-drug exposure. Genotyping identifies that patient as a slow NAT2 acetylator.

Which interpretation best explains the difference?

Greater vascular sensitivity with unchanged drug exposure
Faster conversion to an inactive acetylated metabolite
Reduced acetylation with greater parent-drug exposure
More rapid renal elimination of unchanged hydralazine
Slower gastrointestinal absorption with unchanged overall exposure

Answer and explanations

Best answer: C.

Greater vascular sensitivity with unchanged drug exposure
A PD sensitivity difference would not explain the measured higher parent-drug concentration.
Faster conversion to an inactive acetylated metabolite
Faster inactivation would tend to lower, not raise, parent-drug exposure.
Reduced acetylation with greater parent-drug exposure
Inherited metabolism changes the response to a given oral dose and can alter maintenance-dose requirements. Titration still depends on BP and tolerability.
More rapid renal elimination of unchanged hydralazine
Greater elimination would tend to decrease exposure and does not match the identified acetylator phenotype.
Slower gastrointestinal absorption with unchanged overall exposure
An absorption-rate change alone does not explain the demonstrated greater overall exposure associated with slower metabolism.

Question 13

After many months of oral hydralazine therapy, a patient develops new arthralgia, fever and pleuritic discomfort. Evaluation finds positive ANA and anti-histone antibodies, and hydralazine-induced lupus is suspected.

Which statement best connects the findings to the drug?

An immune-mediated toxicity influenced by exposure and susceptibility
A baroreflex response to arteriolar dilation
A clinical syndrome established by ANA positivity alone
Reduced functional vitamin B₆ availability
Volume expansion from renal sodium retention

Answer and explanations

Best answer: A.

An immune-mediated toxicity influenced by exposure and susceptibility
The clinical pattern supports drug-induced lupus. Longer exposure, higher dose and slower acetylation can contribute; the historical approximately 7% three-year estimate is not an annual rate.
A baroreflex response to arteriolar dilation
The baroreflex explains tachycardia, not the fever, joint and serosal findings.
A clinical syndrome established by ANA positivity alone
Symptoms and clinical assessment distinguish lupus from isolated antibody positivity.
Reduced functional vitamin B₆ availability
A possible antipyridoxine effect is associated with peripheral neuropathy, not the central explanation for this lupus-like syndrome.
Volume expansion from renal sodium retention
Retention explains edema but not this inflammatory clinical and antibody pattern.

Question 14

A patient with severe hypertension refractory to other therapy begins oral minoxidil. Blood pressure improves, but heart rate and body weight rise over the following days.

Which combination most directly addresses the expected compensatory responses?

A β blocker plus a second arteriolar vasodilator
A β blocker or other sympathetic suppressant plus an effective diuretic
A diuretic plus additional minoxidil without sympathetic suppression
A nitrate plus a PDE-5 inhibitor
Two diuretics without any strategy for the increased heart rate

Answer and explanations

Best answer: B.

A β blocker plus a second arteriolar vasodilator
Sympathetic suppression addresses tachycardia, but a second vasodilator does not directly address retained sodium and water.
A β blocker or other sympathetic suppressant plus an effective diuretic
The first limits reflex cardiac stimulation; the second addresses fluid retention. These are usual accompanying measures for oral antihypertensive minoxidil.
A diuretic plus additional minoxidil without sympathetic suppression
A diuretic addresses retention, but escalation alone can intensify reflex tachycardia.
A nitrate plus a PDE-5 inhibitor
This unsafe combination can cause severe hypotension and is not the appropriate response to minoxidil compensation.
Two diuretics without any strategy for the increased heart rate
Volume control alone does not directly address reflex cardiac stimulation.

Question 15

A patient receiving oral minoxidil develops progressive dyspnea and chest discomfort. Echocardiography identifies a new substantial pericardial effusion.

Which interpretation is most appropriate?

The effusion is simply the expected direct arteriolar effect
Improved systemic BP excludes a clinically important pericardial process
Pericardial effusion is specific for hydralazine-induced lupus
A recognized serious minoxidil toxicity requires assessment
Hypertrichosis and pericardial effusion reflect the same harmless local effect

Answer and explanations

Best answer: D.

The effusion is simply the expected direct arteriolar effect
Vascular relaxation is the intended effect; pericardial fluid is a separate potential toxicity.
Improved systemic BP excludes a clinically important pericardial process
A beneficial BP response does not rule out an effusion that compromises filling.
Pericardial effusion is specific for hydralazine-induced lupus
Hydralazine-related serositis is one differential, but minoxidil also has a recognized association with pericardial effusion.
A recognized serious minoxidil toxicity requires assessment
Pericardial effusion, potentially with tamponade, warrants evaluation for hemodynamic compromise and alternative causes.
Hypertrichosis and pericardial effusion reflect the same harmless local effect
Hypertrichosis is distinct from potentially serious pericardial toxicity during systemic treatment.

Question 16

An adult with severe hypertension receives a titrated fenoldopam infusion. The patient has glaucoma, and the clinician also follows serum potassium during treatment.

Which pair of drug-related changes motivates these precautions?

Reduced intraocular pressure and hyperkalemia
Increased intraocular pressure and hyperkalemia
Increased intraocular pressure and hypokalemia
Reduced intraocular pressure and hypokalemia
Unchanged intraocular pressure and potassium because of D₁ selectivity

Answer and explanations

Best answer: C.

Reduced intraocular pressure and hyperkalemia
This reverses both of the relevant label precautions.
Increased intraocular pressure and hyperkalemia
The eye-pressure concern is correct, but the relevant potassium risk is a decrease.
Increased intraocular pressure and hypokalemia
These are recognized fenoldopam precautions. Renal vasodilation does not remove the need to monitor adverse effects.
Reduced intraocular pressure and hypokalemia
The potassium concern is correct, but fenoldopam can increase, rather than reduce, intraocular pressure.
Unchanged intraocular pressure and potassium because of D₁ selectivity
Receptor selectivity does not exclude downstream changes in eye pressure or electrolyte handling.