MED 9408 · 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

Choose an answer to begin.

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Framework practice

Question 1

A drug rapidly lowers arterial pressure by relaxing arteriolar smooth muscle. It has no direct action on the SA node or autonomic receptors, and reflex pathways are intact.

Which compensatory pattern is most likely?

Baroreceptor firing increases; sympathetic output decreases
Baroreceptor firing decreases; sympathetic output increases
Baroreceptor firing decreases; sympathetic output decreases
Baroreceptor firing increases; sympathetic output increases

Answer and explanations

Best answer: B.

Baroreceptor firing increases; sympathetic output decreases
Lower arterial pressure reduces stretch and firing; this pattern would instead follow increased pressure.
Baroreceptor firing decreases; sympathetic output increases
Less arterial stretch reduces baroreceptor firing. The brainstem increases sympathetic output and withdraws cardiac vagal influence, tending to increase heart rate.
Baroreceptor firing decreases; sympathetic output decreases
The sensor response is correct, but sympathetic withdrawal would aggravate the pressure fall.
Baroreceptor firing increases; sympathetic output increases
The sympathetic response is compensatory, but increased baroreceptor firing is inconsistent with reduced stretch.

Question 2

β₁ activation in cardiac muscle and β₂ activation in vascular smooth muscle both increase cAMP, yet the tissues respond differently.

What best explains the different mechanical responses?

β₂ receptors couple to Gq rather than Gs
cAMP increases calcium entry through the same channels in every tissue
Different downstream proteins connect cAMP signaling to each tissue’s contractile machinery
Cardiac cAMP acts only on the nucleus

Answer and explanations

Best answer: C.

β₂ receptors couple to Gq rather than Gs
Both receptor subtypes couple to Gs; different G proteins do not explain this comparison.
cAMP increases calcium entry through the same channels in every tissue
Identical responses in every tissue would not explain cardiac stimulation with smooth-muscle relaxation.
Different downstream proteins connect cAMP signaling to each tissue’s contractile machinery
Cardiac signaling enhances calcium handling, whereas smooth-muscle signaling reduces activation of contraction, including MLCK activity. The tissue’s downstream machinery determines the effect.
Cardiac cAMP acts only on the nucleus
Cardiac cAMP has important effects on ion channels and calcium-handling proteins; its actions are not confined to the nucleus.

Question 3

After renal sympathetic stimulation, plasma renin activity rises even though renal perfusion pressure is held constant in an experiment.

Which receptor action most directly accounts for the renin response?

β₁ activation on juxtaglomerular cells
α₁ activation on renal vascular smooth muscle
β₂ activation on bronchial smooth muscle
Nicotinic activation on adrenal chromaffin cells

Answer and explanations

Best answer: A.

β₁ activation on juxtaglomerular cells
Juxtaglomerular β₁ signaling stimulates renin secretion. Sympathetic activation can therefore recruit a hormonal response as well as immediate cardiac and vascular effects.
α₁ activation on renal vascular smooth muscle
This changes renal vascular tone; the question isolates sympathetic stimulation with perfusion pressure held constant and asks for the direct secretory receptor.
β₂ activation on bronchial smooth muscle
This supports bronchodilation rather than direct renin release.
Nicotinic activation on adrenal chromaffin cells
This releases adrenal catecholamines; it is distinct from the receptor on the renin-secreting cell.

Question 4

A centrally acting α₂ agonist lowers sympathetic nerve activity. A student expects an adrenergic agonist to increase sympathetic effects.

Which explanation resolves this apparent contradiction?

It blocks nicotinic receptors in autonomic ganglia
It directly blocks cardiac β₁ receptors
It activates α₁ receptors on vascular smooth muscle
It activates inhibitory receptors in sympathetic-control networks

Answer and explanations

Best answer: D.

It blocks nicotinic receptors in autonomic ganglia
Ganglionic blockade can reduce autonomic transmission, but it is not the action of an α₂ agonist.
It directly blocks cardiac β₁ receptors
Direct β₁ antagonism is a different mechanism and does not explain an α₂ agonist.
It activates α₁ receptors on vascular smooth muscle
That peripheral action favors vasoconstriction rather than explaining reduced central sympathetic output.
It activates inhibitory receptors in sympathetic-control networks
Central α₂ receptors signal through Gi/o and parallel ion-channel pathways to reduce neuronal activity. Receptor activation can inhibit the output of the circuit containing that receptor.

Question 5

Methyldopa lowers sympathetic influence after entering catecholamine-synthesizing neurons.

Which sequence best explains its central antihypertensive action?

Conversion to dopamine followed by peripheral D₁ blockade
Conversion to α-methylnorepinephrine followed by stimulation of central inhibitory α receptors
Direct irreversible inhibition of vascular α₁ receptors
Conversion to acetylcholine followed by ganglionic blockade

Answer and explanations

Best answer: B.

Conversion to dopamine followed by peripheral D₁ blockade
This is not the relevant active transmitter or target.
Conversion to α-methylnorepinephrine followed by stimulation of central inhibitory α receptors
The active metabolite α-methylnorepinephrine stimulates central inhibitory α-adrenergic pathways, reducing sympathetic outflow. Methyldopa must be distinguished from direct receptor antagonists.
Direct irreversible inhibition of vascular α₁ receptors
That describes neither methyldopa’s activation nor its central action.
Conversion to acetylcholine followed by ganglionic blockade
Methyldopa is processed through catecholamine pathways, not converted into acetylcholine.

Question 6

A patient’s oral clonidine regimen is being changed to a weekly patch. The first patch has just been applied.

Which property makes an immediate equivalent effect unlikely?

Therapeutic drug levels develop gradually after the first application
A new population of α₂ receptors must be synthesized before clonidine can act
The parent drug requires slow conversion to an active catecholamine
Rapid renal elimination prevents sustained drug exposure from any patch

Answer and explanations

Best answer: A.

Therapeutic drug levels develop gradually after the first application
Initial transdermal delivery is slow; therapeutic levels generally develop over 2–3 days. Weekly delivery does not imply immediate onset, so transition planning matters.
A new population of α₂ receptors must be synthesized before clonidine can act
The onset delay arises from delivery and development of drug levels, not a need to replace the target receptors.
The parent drug requires slow conversion to an active catecholamine
Clonidine acts directly; it does not require methyldopa’s catecholamine-metabolite pathway.
Rapid renal elimination prevents sustained drug exposure from any patch
The patch can sustain systemic delivery; the problem is the delay after the first application, not inability to maintain exposure.

Question 7

Two α antagonists produce a similar fall in arterial pressure. One also blocks presynaptic α₂ autoreceptors.

Why can the nonselective drug produce more tachycardia?

It directly stimulates cardiac β₁ receptors
It prevents all baroreflex activation
It increases vagal discharge by blocking vascular α₁ receptors
It removes feedback inhibition of norepinephrine release in addition to recruiting the baroreflex

Answer and explanations

Best answer: D.

It directly stimulates cardiac β₁ receptors
An α antagonist need not be a β₁ agonist to increase cardiac adrenergic stimulation.
It prevents all baroreflex activation
Vasodilation still recruits a compensatory baroreflex.
It increases vagal discharge by blocking vascular α₁ receptors
Vagal withdrawal, not increased vagal influence, contributes to reflex tachycardia after a pressure fall.
It removes feedback inhibition of norepinephrine release in addition to recruiting the baroreflex
Vascular α₁ blockade recruits the reflex. Presynaptic α₂ blockade can additionally increase NE release by removing inhibitory feedback. Selective α₁ blockers preserve that feedback.

Question 8

Vascular responsiveness remains suppressed after phenoxybenzamine has largely disappeared from plasma.

Which property best explains the persistent response?

A shorter plasma half-life necessarily prolongs receptor occupancy
Cardiac β₁ selectivity increases after the drug is cleared
Irreversible receptor binding, with recovery requiring functional receptor replacement
Reversible competitive binding becomes stronger as free drug concentration falls

Answer and explanations

Best answer: C.

A shorter plasma half-life necessarily prolongs receptor occupancy
A short plasma half-life alone does not explain an effect that outlasts circulating drug.
Cardiac β₁ selectivity increases after the drug is cleared
Phenoxybenzamine’s prolonged effect concerns α-receptor binding, not a late change in β₁ selectivity.
Irreversible receptor binding, with recovery requiring functional receptor replacement
Phenoxybenzamine’s irreversible interaction can outlast measurable plasma exposure. Duration of effect is not determined by plasma half-life alone.
Reversible competitive binding becomes stronger as free drug concentration falls
Lower free concentration generally reduces reversible occupancy; this does not explain persistent irreversible blockade.

Question 9

Doxazosin lowers blood pressure. In ALLHAT, its treatment arm nevertheless had more heart-failure events than the chlorthalidone arm.

What principle does this comparison illustrate?

A favorable physiological effect does not establish equivalent clinical outcomes
α₁ blockade cannot lower vascular resistance
Every antihypertensive has identical effects once clinic BP falls
A receptor mechanism establishes a survival benefit without trials

Answer and explanations

Best answer: A.

A favorable physiological effect does not establish equivalent clinical outcomes
Lower BP is a useful physiological effect, but drug-specific outcome trials are needed to establish effects on heart failure and other clinical events.
α₁ blockade cannot lower vascular resistance
α₁ blockade does lower vascular resistance; that fact alone does not settle comparative outcomes.
Every antihypertensive has identical effects once clinic BP falls
Drugs with BP-lowering activity can differ in clinical outcomes and adverse effects.
A receptor mechanism establishes a survival benefit without trials
Mechanistic plausibility cannot substitute for outcome evidence.

Question 10

A β₁-preferring antagonist is given at progressively higher exposure. At the highest exposure, bronchial β₂ blockade becomes more apparent.

Which statement best explains this observation?

β₁ and β₂ receptors have identical drug affinity at every concentration
Selectivity is relative and diminishes as drug exposure increases
Cardioselectivity depends entirely on delivery to the heart, with no drug reaching the lungs
Higher exposure selectively removes β₂ receptors from bronchial tissue

Answer and explanations

Best answer: B.

β₁ and β₂ receptors have identical drug affinity at every concentration
Identical affinity would not explain a concentration range with relative β₁ preference.
Selectivity is relative and diminishes as drug exposure increases
Preference reflects relative affinity, not exclusive binding. Increasing exposure can recruit blockade of less-preferred receptors, so pulmonary risk is reduced rather than eliminated.
Cardioselectivity depends entirely on delivery to the heart, with no drug reaching the lungs
Systemically administered β₁-preferring blockers reach other tissues; preference is not exclusive anatomical delivery.
Higher exposure selectively removes β₂ receptors from bronchial tissue
Receptor removal is not required; increased occupancy of less-preferred receptors explains the effect.

Question 11

A β antagonist with intrinsic sympathomimetic activity produces less resting bradycardia than a pure antagonist, yet limits stimulation when catecholamine concentrations rise.

Which receptor property best explains this pattern?

Irreversible binding without receptor activation
Exclusive vascular α₁ antagonism
Partial agonism at β receptors
Full agonism with greater efficacy than norepinephrine

Answer and explanations

Best answer: C.

Irreversible binding without receptor activation
Irreversibility does not supply the residual stimulation that explains the resting response.
Exclusive vascular α₁ antagonism
α₁ blockade does not define intrinsic sympathomimetic activity at β receptors.
Partial agonism at β receptors
A partial agonist provides some receptor stimulation at low adrenergic tone but competes with higher-efficacy agonists when tone rises.
Full agonism with greater efficacy than norepinephrine
A full agonist would not explain the antagonistic effect during strong catecholamine stimulation.

Question 12

An evidence-based β blocker is started cautiously in stable HFrEF. Its initial negative inotropic effect seems inconsistent with the goal of improving long-term outcomes.

Which explanation best accounts for the time-dependent benefit?

The drug immediately acts as a positive inotrope
All β blockers provide identical HFrEF survival benefits
Reduced contractility proves that cardiac output must always fall permanently
Reducing persistent adrenergic stress can provide long-term protection despite early cardiac suppression

Answer and explanations

Best answer: D.

The drug immediately acts as a positive inotrope
Initial β blockade reduces adrenergic inotropic support rather than directly increasing it.
All β blockers provide identical HFrEF survival benefits
The evidence is agent- and formulation-specific.
Reduced contractility proves that cardiac output must always fall permanently
Cardiac output depends on heart rate, loading conditions and ventricular function as well as contractility; long-term remodeling also matters.
Reducing persistent adrenergic stress can provide long-term protection despite early cardiac suppression
Chronic excessive sympathetic activity contributes to injury and remodeling. Selected β blockers improve outcomes when introduced in appropriately stable patients; this does not justify initiation during shock.

Question 13

Ivabradine slows sinus rate by inhibiting HCN-channel funny current (I_f).

Which change most directly explains the slower rhythm?

A reduced slope of spontaneous phase-4 depolarization in SA-node cells
Blockade of ventricular fast sodium channels during phase 0
Increased calcium entry into ventricular myocytes
Increased norepinephrine release from sympathetic terminals

Answer and explanations

Best answer: A.

A reduced slope of spontaneous phase-4 depolarization in SA-node cells
Less inward pacemaker current delays the next sinus-node threshold crossing.
Blockade of ventricular fast sodium channels during phase 0
Ventricular fast sodium current is not the target responsible for ivabradine’s sinus slowing.
Increased calcium entry into ventricular myocytes
Increased ventricular calcium entry would favor stronger contraction, not explain selective sinus slowing.
Increased norepinephrine release from sympathetic terminals
Greater sympathetic transmitter release would tend to accelerate sinus firing.

Question 14

Two patients have ventricular rates of 90/min. One has sinus rhythm; the other has atrial fibrillation.

Why does the rhythm affect the suitability of sinus-node I_f inhibition?

Ventricular rate alone identifies whether I_f is driving the rhythm
Ivabradine primarily blocks AV-nodal calcium current in either rhythm
During atrial fibrillation, ventricular activation is not paced by regular sinus-node discharge
AF makes β₁ blockade and I_f inhibition pharmacologically equivalent

Answer and explanations

Best answer: C.

Ventricular rate alone identifies whether I_f is driving the rhythm
Equal ventricular rates can arise from different impulse-generating mechanisms.
Ivabradine primarily blocks AV-nodal calcium current in either rhythm
Its relevant target is sinus-node I_f, not the AV-nodal calcium current used by non-DHP CCBs.
During atrial fibrillation, ventricular activation is not paced by regular sinus-node discharge
Sinus-node slowing does not address the mechanism governing ventricular rate in AF. Target location explains why sinus rhythm is required for the studied HFrEF use.
AF makes β₁ blockade and I_f inhibition pharmacologically equivalent
Different target locations continue to matter; these drugs are not interchangeable for AF rate control.

Question 15

An adult meets the labeled criteria for ivabradine treatment of stable symptomatic chronic HFrEF.

Which benefit should be emphasized when explaining this indication?

Immediate reversal of cardiogenic shock
Reduced hospitalization for worsening heart failure
Established prevention of all sudden cardiac deaths
Routine relief of angina in every patient with coronary disease

Answer and explanations

Best answer: B.

Immediate reversal of cardiogenic shock
Acute decompensated HF is a contraindication, not the intended use.
Reduced hospitalization for worsening heart failure
The adult indication is reduction of worsening-HF hospitalization in a defined eligible population.
Established prevention of all sudden cardiac deaths
A reduction in HF hospitalization should not be restated as universal prevention of sudden death.
Routine relief of angina in every patient with coronary disease
Ivabradine is not a routine U.S. angina therapy; its HFrEF indication is specific.

Question 16

After verapamil is given to a person with normal LV function, measured cardiac output is preserved despite a direct negative inotropic effect.

Which explanation is most consistent with this finding?

Preserved output proves that contractility increased
Cardiac output and contractility are interchangeable terms
Verapamil has no direct cardiac action in normal ventricles
Afterload reduction and compensatory responses can offset part of the direct cardiac depression

Answer and explanations

Best answer: D.

Preserved output proves that contractility increased
Output alone does not establish an increase in intrinsic contractility.
Cardiac output and contractility are interchangeable terms
Output is HR × stroke volume; contractility is only one determinant of stroke volume.
Verapamil has no direct cardiac action in normal ventricles
Verapamil still reduces calcium-dependent cardiac activity.
Afterload reduction and compensatory responses can offset part of the direct cardiac depression
Lower resistance to LV ejection and reflex support can help maintain output even while direct negative inotropy persists. LV reserve affects the net response.

Question 17

A CYP3A inhibitor is added while the prescribed dose of verapamil remains unchanged. Verapamil exposure increases.

Which consequence follows most directly from the higher exposure?

Bradycardia becomes less likely because the prescribed dose is unchanged
Vascular resistance rises because metabolism is inhibited
Bradycardia and hypotension can become more likely
The interaction affects only an inactive metabolite and cannot alter the parent drug

Answer and explanations

Best answer: C.

Bradycardia becomes less likely because the prescribed dose is unchanged
The unchanged dose does not prevent higher exposure or amplified nodal effects.
Vascular resistance rises because metabolism is inhibited
Higher verapamil exposure does not turn its vascular action into vasoconstriction.
Bradycardia and hypotension can become more likely
Increased exposure can amplify the existing effects on nodal activity, cardiac function and vascular tone.
The interaction affects only an inactive metabolite and cannot alter the parent drug
CYP3A inhibition can increase verapamil exposure itself; the premise identifies that increase.

Question 18

Verapamil commonly causes constipation, in addition to its cardiac and vascular effects.

Which explanation best connects this adverse effect to tissue pharmacology?

Inhibition of calcium-dependent intestinal smooth-muscle activity can slow transit
Activation of intestinal μ-opioid receptors reduces propulsive motility
Blockade of muscarinic receptors suppresses enteric cholinergic signaling
Enhanced water excretion dehydrates stool through a direct diuretic action

Answer and explanations

Best answer: A.

Inhibition of calcium-dependent intestinal smooth-muscle activity can slow transit
Smooth-muscle contraction depends on calcium. Reduced intestinal motor activity helps explain verapamil-associated constipation.
Activation of intestinal μ-opioid receptors reduces propulsive motility
This can cause constipation with opioids, but verapamil does not act through μ receptors.
Blockade of muscarinic receptors suppresses enteric cholinergic signaling
Antimuscarinic drugs can cause constipation; verapamil’s principal relevant target is the L-type calcium channel.
Enhanced water excretion dehydrates stool through a direct diuretic action
Verapamil is not a diuretic; altered intestinal motility is the relevant link.

Question 19

Two DHP formulations lower vascular resistance, but one produces a much more rapid fall in BP.

Which difference in response is most likely with the rapid-onset formulation?

Greater direct AV-nodal suppression
Greater baroreflex sympathetic activation
Greater blockade of sympathetic nerve transmission at autonomic ganglia
Less reflex tachycardia because rapid vasodilation directly slows the SA node

Answer and explanations

Best answer: B.

Greater direct AV-nodal suppression
DHPs are predominantly vascular; direct nodal suppression does not explain the onset effect.
Greater baroreflex sympathetic activation
A rapid pressure fall can recruit stronger reflex sympathetic activation and tachycardia. Onset and formulation alter the net response to a similar vascular target.
Greater blockade of sympathetic nerve transmission at autonomic ganglia
DHPs act mainly on vascular calcium channels, not as ganglionic blockers.
Less reflex tachycardia because rapid vasodilation directly slows the SA node
Rapid vascular dilation can increase reflex tachycardia; DHPs do not provide the direct nodal slowing of non-DHP CCBs.

Question 20

Ankle edema develops during DHP treatment without evidence of generalized volume overload.

Which vascular change best explains the edema?

Equal constriction of pre- and postcapillary vessels
Reduced capillary hydrostatic pressure
Preferential postcapillary dilation with reduced filtration
Precapillary dilation exceeding postcapillary dilation

Answer and explanations

Best answer: D.

Equal constriction of pre- and postcapillary vessels
This does not describe the DHP microcirculatory effect.
Reduced capillary hydrostatic pressure
Lower hydrostatic pressure would oppose fluid filtration.
Preferential postcapillary dilation with reduced filtration
Preferential postcapillary dilation would tend to lower capillary pressure.
Precapillary dilation exceeding postcapillary dilation
Unequal dilation raises capillary hydrostatic pressure and promotes fluid movement into dependent tissues. This differs from generalized salt-and-water overload.

Question 21

A DHP improves exertional angina while resting heart rate changes little.

Which effect can contribute to symptom relief?

Arteriolar dilation reduces resistance to LV ejection
I_f inhibition slows sinus-node automaticity
β₁ blockade reduces cardiac adrenergic drive
Predominant venodilation reduces venous return

Answer and explanations

Best answer: A.

Arteriolar dilation reduces resistance to LV ejection
Reduced afterload can reduce myocardial work and oxygen demand; coronary dilation can also contribute. Antianginal benefit need not require slowing the heart.
I_f inhibition slows sinus-node automaticity
This describes ivabradine’s target, not the predominant DHP mechanism.
β₁ blockade reduces cardiac adrenergic drive
This describes β blockers rather than DHP calcium-channel blockers.
Predominant venodilation reduces venous return
This describes the predominant hemodynamic action of nitrates, which are discussed separately. DHPs act mainly on the arterial side.

Question 22

Ranolazine inhibits cardiac late sodium current at therapeutic concentrations. A diagram links this effect to reduced calcium loading and improved relaxation.

Which statement best separates established pharmacology from the proposed explanation of symptom relief?

Late-current inhibition proves the complete antianginal mechanism
The exact antianginal mechanism is undetermined despite demonstrated late-current inhibition
Ranolazine requires a large fall in BP to relieve angina
Ranolazine has no measurable action on ion currents

Answer and explanations

Best answer: B.

Late-current inhibition proves the complete antianginal mechanism
A molecular action does not by itself establish the complete chain producing a clinical benefit.
The exact antianginal mechanism is undetermined despite demonstrated late-current inhibition
Late-current inhibition is established, while its precise contribution to antianginal benefit remains uncertain. The cellular pathway should be taught as a proposed explanation.
Ranolazine requires a large fall in BP to relieve angina
Its clinical benefit occurs with minimal effects on HR and BP.
Ranolazine has no measurable action on ion currents
The uncertainty concerns the link to benefit, not whether ion-current effects occur.

Question 23

A patient taking ranolazine develops a longer QT interval.

Which ion-current effect explains this separate pharmacologic action?

Enhancement of SA-node I_f
Opening of ventricular fast sodium channels
Inhibition of the rapid delayed-rectifier potassium current, I_Kr
Blockade of vascular α₁ receptors

Answer and explanations

Best answer: C.

Enhancement of SA-node I_f
Pacemaker I_f is not the ventricular repolarizing current at issue.
Opening of ventricular fast sodium channels
Ranolazine’s QT effect is not explained by opening fast sodium channels.
Inhibition of the rapid delayed-rectifier potassium current, I_Kr
Reduced outward I_Kr delays ventricular repolarization and can lengthen QT. This is distinct from late inward sodium-current inhibition.
Blockade of vascular α₁ receptors
Vascular α₁ blockade does not explain this direct repolarization effect.

Question 24

Ranolazine and a strong CYP3A inhibitor are being considered together.

Why is this combination contraindicated?

Reduced absorption lowers ranolazine concentrations below the effective range
Increased CYP3A-mediated clearance shortens ranolazine exposure
Accelerated renal elimination prevents therapeutic concentrations
Inhibited metabolism can markedly increase ranolazine exposure

Answer and explanations

Best answer: D.

Reduced absorption lowers ranolazine concentrations below the effective range
Strong CYP3A inhibition causes the opposite exposure concern: concentrations can rise.
Increased CYP3A-mediated clearance shortens ranolazine exposure
Enzyme inhibition reduces metabolic clearance rather than inducing it.
Accelerated renal elimination prevents therapeutic concentrations
The interaction is not explained by accelerated renal removal; the key issue is inhibited metabolism.
Inhibited metabolism can markedly increase ranolazine exposure
Higher exposure increases concentration-dependent toxicity, including QT effects. Limited effects on BP do not eliminate pharmacokinetic safety concerns.

Clinical vignettes

Question 1

A 58-year-old man has taken oral clonidine for several years. During two days of vomiting he misses every dose. He develops severe headache, sweating and tremor. BP is 214/118 mm Hg and pulse is 116/min. He has not taken stimulants.

Which change most directly explains this presentation?

Increased central α₂-receptor stimulation
Irreversible destruction of adrenal catecholamine stores
Loss of central inhibition with a surge in sympathetic output
Complete blockade of vascular α₁ receptors
Increased cardiac vagal activity

Answer and explanations

Best answer: C.

Increased central α₂-receptor stimulation
Increased inhibitory stimulation would tend to lower sympathetic activity.
Irreversible destruction of adrenal catecholamine stores
Catecholamine depletion would not explain adrenergic overactivity.
Loss of central inhibition with a surge in sympathetic output
Abrupt loss of chronic clonidine action can produce rebound sympathetic activity. The missed doses and adrenergic findings point to withdrawal.
Complete blockade of vascular α₁ receptors
Vascular α₁ blockade would favor lower resistance and orthostatic symptoms.
Increased cardiac vagal activity
Greater vagal influence would slow the heart, unlike the observed tachycardia.

Question 2

A 35-year-old woman treated with methyldopa for several months develops fatigue and mild jaundice. Hemoglobin has fallen, reticulocytes and indirect bilirubin are elevated, and the direct antiglobulin test is positive.

Which mechanism best explains her anemia?

Reduced red-cell production from marrow suppression
Oxidative red-cell injury associated with G6PD deficiency
Chronic gastrointestinal blood loss
Mechanical fragmentation of red cells in small vessels
Drug-associated immune destruction of erythrocytes

Answer and explanations

Best answer: E.

Reduced red-cell production from marrow suppression
Reticulocytosis indicates a marrow response; the antiglobulin result favors immune destruction.
Oxidative red-cell injury associated with G6PD deficiency
Oxidative hemolysis is generally antiglobulin-negative and does not explain antibody-coated red cells.
Chronic gastrointestinal blood loss
Blood loss does not account for the combination of indirect hyperbilirubinemia and a positive direct antiglobulin test.
Mechanical fragmentation of red cells in small vessels
Microangiopathic hemolysis is associated with red-cell fragmentation and is generally antiglobulin-negative.
Drug-associated immune destruction of erythrocytes
Methyldopa can cause antibody-associated hemolytic anemia. This toxicity is separate from its central antihypertensive receptor mechanism. A positive test alone does not establish hemolysis, but this patient also has evidence of red-cell destruction.

Question 3

A 67-year-old man takes his first dose of prazosin at bedtime. When he stands to use the bathroom, he becomes lightheaded. BP falls from 132/78 mm Hg supine to 96/60 mm Hg standing; pulse increases. There is no bleeding or recent fluid loss.

Which response is most directly impaired?

Reflex α₁-mediated constriction of resistance and capacitance vessels
Detection of reduced stretch by arterial baroreceptors
Increased sympathetic output from brainstem circuits
β₁-mediated acceleration of sinus-node firing
Release of catecholamines from the adrenal medulla

Answer and explanations

Best answer: A.

Reflex α₁-mediated constriction of resistance and capacitance vessels
Standing promotes venous pooling. α₁ blockade impairs compensatory venous and arteriolar constriction, reducing venous return and pressure despite an increased pulse.
Detection of reduced stretch by arterial baroreceptors
Prazosin blocks an effector receptor rather than disabling the arterial stretch sensor.
Increased sympathetic output from brainstem circuits
The reflex can increase sympathetic output, but the blocked vessels cannot respond normally.
β₁-mediated acceleration of sinus-node firing
The observed pulse increase suggests this response remains available; prazosin is not a β₁ blocker.
Release of catecholamines from the adrenal medulla
Prazosin does not work by inhibiting catecholamine release from the adrenal medulla.

Question 4

A 71-year-old man has urinary hesitancy and a weak stream from benign prostatic enlargement. His BP is 114/70 mm Hg. Tamsulosin improves urine flow without a substantial change in BP.

Which action most directly accounts for the urinary benefit?

Reduction of prostate volume through 5α-reductase inhibition
Relaxation of prostate and bladder-neck smooth muscle through α₁ blockade
Suppression of detrusor contraction through muscarinic blockade
Lowering of systemic arterial resistance through vascular α₁ blockade
Relaxation of the detrusor during bladder filling through β₃ activation

Answer and explanations

Best answer: B.

Reduction of prostate volume through 5α-reductase inhibition
A 5α-reductase inhibitor reduces the static component of obstruction over time; it is a different class.
Relaxation of prostate and bladder-neck smooth muscle through α₁ blockade
Blockade of α₁ receptors in the urinary outlet reduces smooth-muscle tone. Relative urinary selectivity limits BP effects but does not eliminate orthostatic risk.
Suppression of detrusor contraction through muscarinic blockade
Suppressing detrusor contraction does not explain improved emptying through a relaxed outlet.
Lowering of systemic arterial resistance through vascular α₁ blockade
Vascular relaxation explains a BP effect, not the local urinary-outlet benefit.
Relaxation of the detrusor during bladder filling through β₃ activation
β₃ agonists affect bladder storage rather than relaxing the prostate and bladder neck in this way.

Question 5

A 28-year-old woman with previously well-controlled asthma begins propranolol for migraine prevention. Several days later, she develops wheezing and a decrease in peak expiratory flow. She has no fever or upper-respiratory symptoms.

Which action best explains the new respiratory findings?

Stimulation of bronchial α₂ receptors
Inhibition of central norepinephrine synthesis
Activation of vascular L-type calcium channels
Blockade of β₂-mediated bronchial smooth-muscle relaxation
Inhibition of the sinus-node funny current

Answer and explanations

Best answer: D.

Stimulation of bronchial α₂ receptors
Propranolol is a β antagonist, not an α₂ agonist.
Inhibition of central norepinephrine synthesis
Its pulmonary effect is peripheral receptor blockade rather than inhibition of transmitter synthesis.
Activation of vascular L-type calcium channels
It does not act by opening vascular calcium channels.
Blockade of β₂-mediated bronchial smooth-muscle relaxation
Nonselective β blockade removes β₂-mediated bronchodilator support and can provoke bronchospasm even when asthma was controlled before treatment.
Inhibition of the sinus-node funny current
I_f inhibition explains ivabradine’s sinus slowing, not propranolol-related wheezing.

Question 6

A 23-year-old man using insulin develops hypoglycemia after exercise. Since starting propranolol, episodes have involved less tachycardia and more prolonged recovery, although sweating still occurs.

Which receptor effect most directly contributes to delayed glucose recovery?

β₁ blockade that reduces juxtaglomerular renin release
β₂ blockade that limits adrenergic support of hepatic glucose release
α₂ activation that inhibits pancreatic insulin secretion
Muscarinic blockade that suppresses sweating
β₁ blockade that reduces sinus-node firing

Answer and explanations

Best answer: B.

β₁ blockade that reduces juxtaglomerular renin release
Reduced renin release does not directly explain impaired glucose mobilization.
β₂ blockade that limits adrenergic support of hepatic glucose release
β₂ blockade can impair adrenergic glucose mobilization. This accounts for delayed recovery, rather than simply loss of a warning symptom.
α₂ activation that inhibits pancreatic insulin secretion
Propranolol does not activate α₂ receptors, and reduced insulin secretion would not explain this β-blocker effect.
Muscarinic blockade that suppresses sweating
Propranolol does not block muscarinic receptors; sweating can persist because sweat-gland transmission is cholinergic.
β₁ blockade that reduces sinus-node firing
This explains blunted tachycardia, but the question asks why glucose recovery is delayed.

Question 7

A 62-year-old man has stable symptomatic HFrEF with LVEF 30%. He is euvolemic, with BP 126/76 mm Hg and pulse 86/min. He also has asthma, currently without wheezing. His cardiologist plans cautious β-blocker initiation with pulmonary monitoring.

Which listed regimen best combines HFrEF outcome evidence with relative β₁ selectivity?

Propranolol
Metoprolol tartrate
Atenolol
Pindolol
Metoprolol succinate extended release

Answer and explanations

Best answer: E.

Propranolol
Propranolol is nonselective and is not an evidence-based HFrEF agent.
Metoprolol tartrate
It has β₁ preference, but the HFrEF outcome evidence supporting metoprolol is for the succinate extended-release formulation.
Atenolol
β₁ preference alone does not establish the HFrEF outcome evidence required here.
Pindolol
Intrinsic sympathomimetic activity does not provide the established HFrEF outcome benefit sought in this case.
Metoprolol succinate extended release
This formulation has HFrEF outcome evidence and β₁ preference. Absence of wheezing does not eliminate bronchospasm risk; initiation still requires individualized assessment and monitoring.

Question 8

A patient undergoing a procedure develops a sustained supraventricular tachycardia. A titratable IV β₁-preferring blocker is selected. Its effect wanes rapidly after the infusion stops; its elimination half-life is approximately nine minutes.

Which drug most closely matches this exposure profile?

Esmolol
Nadolol
Propranolol
Bisoprolol
Metoprolol succinate extended release

Answer and explanations

Best answer: A.

Esmolol
Esmolol undergoes rapid esterase metabolism and is suited to short, titratable IV β blockade.
Nadolol
Nadolol has prolonged exposure and depends on renal elimination.
Propranolol
Propranolol is nonselective and does not have esmolol’s very short elimination profile.
Bisoprolol
Bisoprolol is a longer-acting oral β₁-preferring agent.
Metoprolol succinate extended release
The extended-release preparation is intended for sustained oral exposure, not a brief IV effect.

Question 9

A 59-year-old woman has stable symptomatic chronic HFrEF despite appropriate background therapy, including maximally tolerated carvedilol. LVEF is 30%, BP is 118/72 mm Hg and ECG shows sinus rhythm at 82/min. An additional drug is prescribed to reduce hospitalization for worsening HF without directly depressing ventricular contractility.

Which drug best fits this purpose?

Verapamil
Diltiazem
Ivabradine
Pindolol
Ranolazine

Answer and explanations

Best answer: C.

Verapamil
Verapamil depresses cardiac contractility and is unsuitable for this HFrEF purpose.
Diltiazem
Diltiazem also has negative inotropic effects and does not provide this HFrEF indication.
Ivabradine
Her rhythm, EF and resting rate fit adult ivabradine eligibility on maximally tolerated β blockade. I_f inhibition adds sinus slowing; the relevant demonstrated benefit is fewer worsening-HF hospitalizations.
Pindolol
Pindolol lacks the relevant HFrEF outcome evidence and has partial agonist activity.
Ranolazine
Ranolazine is used for chronic angina rather than this hospitalization-reduction indication.

Question 10

A 64-year-old man taking ivabradine for HFrEF develops palpitations. ECG now shows an irregularly irregular ventricular rhythm without discrete P waves. The clinician reassesses the medication rather than escalating its dose to control the new rhythm.

Which physiological fact best explains this decision?

Ventricular rate in AF is normally set by I_f in the AV node
AF prevents ivabradine from entering the circulation
A higher sinus rate is the primary generator of AF
The ventricular rhythm is no longer paced by regular sinus-node discharge
Ivabradine increases AV-nodal conduction when atrial rates rise

Answer and explanations

Best answer: D.

Ventricular rate in AF is normally set by I_f in the AV node
The relevant clinical action is sinus-node slowing; ivabradine is not an AV-nodal rate-control drug for AF.
AF prevents ivabradine from entering the circulation
A change in rhythm does not eliminate systemic absorption.
A higher sinus rate is the primary generator of AF
AF involves disorganized atrial activation rather than simply faster sinus firing.
The ventricular rhythm is no longer paced by regular sinus-node discharge
The ECG indicates AF, for which sinus-node slowing is not an effective ventricular rate-control mechanism. AF is also a recognized safety concern during ivabradine therapy.
Ivabradine increases AV-nodal conduction when atrial rates rise
The problem is that its target does not govern this rhythm, not that it becomes an AV-nodal stimulant.

Question 11

A 73-year-old man taking metoprolol begins verapamil. He subsequently develops dizziness, a pulse of 38/min and second-degree AV block. Electrolytes are normal, and there is no evidence of an acute myocardial infarction.

Which interaction best explains the conduction abnormality?

Additive suppression of cardiac nodal activity through different targets
Competitive activation of β₁ receptors
Excess activation of the renin–angiotensin system
Reduced intestinal verapamil absorption
Reversal of metoprolol’s receptor binding

Answer and explanations

Best answer: A.

Additive suppression of cardiac nodal activity through different targets
β blockade and non-DHP calcium-channel blockade converge on rate and AV conduction. Their effects can add even though the molecular targets differ.
Competitive activation of β₁ receptors
Both drugs reduce cardiac stimulation rather than jointly activate β₁ receptors.
Excess activation of the renin–angiotensin system
RAAS activation does not explain this direct nodal interaction.
Reduced intestinal verapamil absorption
Reduced verapamil exposure would not explain increased nodal suppression.
Reversal of metoprolol’s receptor binding
Loss of β blockade would tend to remove, rather than intensify, nodal slowing.

Question 12

A 76-year-old woman taking a stable digoxin dose begins verapamil. Digoxin concentration subsequently rises despite unchanged renal function and dosing. She develops nausea and bradycardia.

Which additional action of verapamil can contribute to the increased digoxin exposure?

Induction of P-glycoprotein efflux
Inhibition of CYP3A-dependent digoxin metabolism
Reduced intestinal absorption of digoxin
Increased glomerular filtration of digoxin
Inhibition of P-glycoprotein-mediated transport

Answer and explanations

Best answer: E.

Induction of P-glycoprotein efflux
Inducing efflux would not explain the observed rise in exposure.
Inhibition of CYP3A-dependent digoxin metabolism
Although verapamil inhibits CYP3A, digoxin is not cleared principally through CYP3A metabolism. Distinguish enzyme inhibition from transporter inhibition.
Reduced intestinal absorption of digoxin
Reduced absorption would tend to lower exposure.
Increased glomerular filtration of digoxin
Greater filtration would favor elimination rather than accumulation.
Inhibition of P-glycoprotein-mediated transport
Inhibition of P-glycoprotein can increase digoxin exposure. This pharmacokinetic effect is separate from additive slowing of AV conduction by the two drugs.

Question 13

A 61-year-old woman develops bilateral ankle swelling after her amlodipine dose is increased. Lungs are clear, jugular venous pressure is normal and renal function is unchanged. Swelling is worse at the end of the day.

Which change best explains the swelling?

Uniform dilation of arterioles and venules with lower capillary pressure
Increased capillary hydrostatic pressure from preferential arteriolar dilation
Generalized sodium retention from direct aldosterone-receptor stimulation
Impaired venous flow from bilateral acute thrombosis
Reduced filtration caused by increased plasma oncotic pressure

Answer and explanations

Best answer: B.

Uniform dilation of arterioles and venules with lower capillary pressure
Balanced dilation with lower pressure would not explain increased filtration.
Increased capillary hydrostatic pressure from preferential arteriolar dilation
Precapillary dilation exceeds postcapillary dilation, raising capillary pressure and moving fluid into dependent tissue. The examination does not suggest generalized congestion.
Generalized sodium retention from direct aldosterone-receptor stimulation
Amlodipine is not an aldosterone-receptor agonist.
Impaired venous flow from bilateral acute thrombosis
The timing and symmetric dependent pattern favor the medication effect, without evidence given for thrombosis.
Reduced filtration caused by increased plasma oncotic pressure
Reduced filtration would oppose edema formation.

Question 14

A 47-year-old woman has a sudden severe headache and is diagnosed with subarachnoid hemorrhage from a ruptured intracranial aneurysm. After aneurysm treatment, an enteral DHP calcium-channel blocker is included to improve neurological outcome.

Which drug is being used?

Nicardipine
Clevidipine
Nimodipine
Amlodipine
Nifedipine

Answer and explanations

Best answer: C.

Nicardipine
IV nicardipine can be used for BP control, but it is not the enteral agent with the specific neurological-outcome role described.
Clevidipine
Clevidipine is a short-acting IV antihypertensive, not the enteral therapy described.
Nimodipine
Nimodipine is used after aneurysmal SAH to improve neurological outcome. This benefit should not simply be equated with reversal of angiographic vasospasm.
Amlodipine
Amlodipine treats hypertension and angina, not this specific aSAH indication.
Nifedipine
Nifedipine does not replace nimodipine for this neurological-outcome indication.

Question 15

A 60-year-old man had a coronary stent six years ago. He has predictable exertional chest discomfort three to four times weekly, relieved by rest or sublingual nitroglycerin, with no recent change in pattern. Current therapy includes metoprolol succinate 100 mg/day, lisinopril, aspirin and atorvastatin. HR is 58/min, BP 155/95 mm Hg and LVEF 55%.

Which additional drug is the best choice for this patient?

Increase metoprolol
Add verapamil
Add amlodipine
Add ranolazine

Answer and explanations

Best answer: C.

Increase metoprolol
The resting pulse already limits additional rate slowing.
Add verapamil
Verapamil would add AV-nodal suppression to metoprolol despite an already-low pulse.
Add amlodipine
Amlodipine can relieve angina and lower BP without substantial direct AV-nodal suppression. It best addresses the overall presentation among these choices.
Add ranolazine
Ranolazine would treat the angina, but its minimal BP effect means separate BP management would still be required.

Question 16

The same patient has persistent stable exertional angina, but now his HR is 58/min and BP is 106/66 mm Hg. He remains on a tolerated metoprolol regimen and has preserved LVEF. His QT interval, kidney and liver function, and drug interactions have been reviewed and do not preclude treatment.

Which additional drug is the best choice for this patient?

Increase metoprolol
Add verapamil
Add amlodipine
Add ranolazine

Answer and explanations

Best answer: D.

Increase metoprolol
Increasing metoprolol would add rate slowing when the pulse is already 58/min.
Add verapamil
Verapamil adds nodal slowing and can further lower BP.
Add amlodipine
Amlodipine could relieve angina, but its BP-lowering effect is less desirable with this presentation; the BP is not itself an absolute contraindication.
Add ranolazine
Ranolazine provides angina relief with little additional HR or BP reduction. The options are identical to the preceding case; the changed BP alters which drug best fits.