Antihypertensive Drugs

Correct Answer

C — Thiazide-type diuretic

Rationale

Chlorthalidone is a thiazide-type diuretic. Furosemide is a loop diuretic. Amiloride is a potassium-sparing diuretic. Acetazolamide is a carbonic anhydrase inhibitor.

Correct Answer

A — Thiazide-like diuretics

Rationale

Indapamide is a thiazide-like diuretic, structurally distinct from but functionally similar to the thiazide diuretics. Hydrochlorothiazide is a thiazide diuretic. Torsemide is a loop diuretic. Triamterene is a potassium-sparing diuretic.

Correct Answer

D — Dihydropyridine calcium channel blockers

Rationale

Amlodipine is a dihydropyridine calcium channel blocker. Verapamil and diltiazem are non-dihydropyridine calcium channel blockers.

Correct Answer

B — Centrally acting alpha-2 adrenergic receptor agonists

Rationale

Clonidine and methyldopa are both centrally acting alpha-2 adrenergic receptor agonists. Amlodipine is a dihydropyridine calcium channel blocker. Losartan is an angiotensin receptor blocker. Indapamide is a thiazide-like diuretic.

Correct Answer

C — Selective alpha-1 adrenergic receptor antagonist

Rationale

Doxazosin is a selective alpha-1 adrenergic receptor antagonist. Metoprolol is a selective beta-1 adrenergic receptor antagonist. Clonidine is a centrally acting alpha-2 adrenergic receptor agonist. Verapamil is a non-dihydropyridine calcium channel blocker.

Correct Answer

A — Selective beta-1 adrenergic receptor antagonists

Rationale

Bisoprolol and nebivolol are both selective beta-1 adrenergic receptor antagonists. Propranolol is a nonselective beta-adrenergic receptor antagonist. Doxazosin is an alpha-1 adrenergic receptor antagonist. Clonidine is a centrally acting alpha-2 adrenergic receptor agonist.

Correct Answer

D — Age-related arterial stiffness eliminates the aortic Windkessel effect — the compliant aorta can no longer absorb stroke volume during systole or recoil during diastole, so systolic pressure rises sharply and diastolic pressure falls as reflected pulse waves return earlier in the cardiac cycle

Rationale

The Windkessel effect describes the normal role of the compliant aorta in buffering each cardiac stroke: during systole, the elastic aorta expands to store part of the stroke volume, dampening the systolic pressure rise; during diastole, elastic recoil of the stored volume maintains pressure and coronary perfusion. With aging, elastin fibers in the aortic wall fragment and are replaced by stiffer collagen; advanced glycation end products cross-link these collagen molecules further; and medial calcification adds rigidity. The stiff aorta can no longer perform this buffering — each stroke volume is transmitted directly and forcefully, producing a higher systolic peak. Simultaneously, because the arterial walls are stiff, pulse waves generated by cardiac contraction travel faster and return from peripheral reflection sites earlier — now arriving during late systole rather than diastole, augmenting systolic pressure while reducing the diastolic component. The clinical result is isolated systolic hypertension with a wide pulse pressure, which is the dominant pattern in patients over 60 years of age and a stronger predictor of cardiovascular events than diastolic blood pressure in this age group.

Correct Answer

B — Coronary arteries fill predominantly during diastole — when diastolic pressure is too low, coronary perfusion pressure falls below the autoregulatory floor, impairing myocardial blood flow to areas supplied by stenosed vessels

Rationale

The heart is unique among organs in that most of its blood supply arrives during diastole, not systole. During systole, myocardial wall tension compresses intramural coronary vessels, reducing flow. During diastole, the relaxed myocardium allows coronary filling driven by aortic diastolic pressure. In patients with coronary artery disease, stenotic vessels already have reduced perfusion reserve and depend more acutely on adequate perfusion pressure. The coronary circulation can autoregulate blood flow across a range of perfusion pressures, but when diastolic pressure falls below approximately 65 to 70 millimeters of mercury, the autoregulatory reserve may be exceeded in territories supplied by stenotic vessels, producing myocardial ischemia. This relationship is termed the J-curve phenomenon: at very low diastolic pressures, cardiovascular event rates paradoxically rise even though overall blood pressure is lower. In elderly patients with isolated systolic hypertension and concurrent coronary artery disease, the treatment goal is to reduce systolic blood pressure while accepting that diastolic blood pressure cannot be driven below 65 to 70 millimeters of mercury without cardiac risk.

Correct Answer

A — A fall in systolic blood pressure of at or above 20 millimeters of mercury or diastolic blood pressure of at or above 10 millimeters of mercury within 3 minutes of standing; alpha-1 blockers, loop diuretics, and calcium channel blockers are the most problematic classes

Rationale

Orthostatic hypotension is defined by consensus as a fall in systolic blood pressure of 20 millimeters of mercury or more, or a fall in diastolic blood pressure of 10 millimeters of mercury or more, within 3 minutes of moving from a supine or seated position to standing. The definition does not require symptoms — asymptomatic orthostatic hypotension is still clinically relevant because it is associated with approximately twice the risk of falls, syncope, and cardiovascular events compared with normotensive elderly individuals. Prevalence is approximately 20 percent in community-dwelling elderly patients, rising above 50 percent in institutionalized elderly. Among antihypertensive drug classes, alpha-1 blockers are the most problematic because they produce rapid venodilation and reduce the sympathetic vasoconstriction that normally compensates for postural blood pressure changes. Loop diuretics cause volume depletion that reduces venous return on standing. Calcium channel blockers dilate arterioles and impair the normal vasoconstrictor response to standing. Blood pressure must be measured in both sitting and standing positions at every visit in elderly hypertensive patients — a requirement that is often neglected in clinical practice.

Correct Answer

C — Declining glomerular filtration rate causes renally excreted drugs such as atenolol and lisinopril to accumulate; reduced hepatic blood flow raises oral bioavailability of drugs such as metoprolol and labetalol by reducing first-pass metabolism

Rationale

Two pharmacokinetic changes are particularly relevant to antihypertensive prescribing in the elderly. First, glomerular filtration rate declines by approximately 1 milliliter per minute per year after age 40. This means that renally excreted drugs — including atenolol, lisinopril, and enalaprilat — accumulate progressively as patients age, reaching higher steady-state plasma levels than in younger patients on the same dose. For atenolol, this accumulation contributes to bradycardia, fatigue, and blocks of cardiac conduction. The Chronic Kidney Disease Epidemiology Collaboration equation should be used to estimate renal function because serum creatinine alone overestimates renal function in the elderly (reduced muscle mass generates less creatinine). Second, hepatic blood flow decreases with age, reducing the fraction of an oral dose eliminated during first-pass metabolism by the liver. This increases the bioavailability of high-extraction hepatic drugs — including metoprolol, propranolol, labetalol, and immediate-release nifedipine — so that standard oral doses produce higher plasma concentrations in elderly patients than in younger adults. An additional pharmacokinetic consideration is that lipophilic drugs (lipid-soluble drugs) have a larger apparent volume of distribution in the elderly because body fat increases relative to lean mass, and they cross the blood-brain barrier more readily, increasing central nervous system adverse effects.

Correct Answer

D — Begin at half the standard starting dose and titrate slowly at 4 to 6 week intervals — reduced drug clearance, impaired compensatory reflexes, and multiple drug interactions in patients taking 5 to 7 medications make elderly patients more susceptible to adverse effects from rapid dose escalation

Rationale

The start-low, go-slow principle for elderly patients reflects the intersection of several pharmacological and physiological vulnerabilities. Reduced renal and hepatic drug clearance means that standard doses produce higher plasma levels than in younger adults. Impaired baroreceptor sensitivity means that blood pressure falls cannot be adequately compensated by the usual reflex tachycardia and vasoconstriction — making blood pressure drops more pronounced and more symptomatic. Reduced autonomic reserve impairs postural responses, increasing orthostatic hypotension risk with each dose increase. The average elderly hypertensive patient takes 5 to 7 prescription medications, and each new antihypertensive adds to an existing pharmacological burden with potential for additive hypotensive effects and drug interactions. Practical dose targets in the elderly include chlorthalidone 6.25 mg, amlodipine 2.5 mg, and perindopril 2 mg as starting doses. Titration should occur no faster than every 4 to 6 weeks to allow full assessment of tolerance and stability at each dose level before proceeding to a higher one. A second agent should only be added after confirming that the first is well tolerated.

Correct Answer

B — Lipophilic beta-blockers such as metoprolol and propranolol cause fatigue, sleep disturbance, and mild cognitive effects; centrally acting agents such as clonidine and methyldopa cause sedation, confusion, and depression; amlodipine, chlorthalidone, and angiotensin receptor blockers are considered cognitively neutral

Rationale

The cognitive effects of antihypertensives in the elderly are clinically relevant given the high prevalence of mild cognitive impairment in this population. Lipophilic beta-adrenergic receptor antagonists — metoprolol, propranolol — cross the blood-brain barrier more readily than hydrophilic agents and cause fatigue, vivid dreams, sleep disturbance, and mild cognitive effects at high doses. These effects are amplified in the elderly because lipophilic drugs have a larger volume of distribution in aging bodies (proportionally greater adipose tissue) and reduced hepatic first-pass metabolism raises their bioavailability. Centrally acting agents — clonidine and methyldopa — directly suppress central sympathetic tone but in doing so also cause sedation, confusion, depression, and falls, as the aging brain has reduced neurotransmitter reserve. Amlodipine, chlorthalidone, and angiotensin receptor blockers do not appreciably cross the blood-brain barrier, do not suppress central neurotransmitter systems, and are classified as cognitively neutral — they are the preferred agents when cognitive protection is a treatment priority. It is worth acknowledging that hypertension itself is a major risk factor for dementia, so treating blood pressure appropriately protects cognition — the goal is to choose agents that lower blood pressure without adding cognitive burden.

Correct Answer

A — Thiazide-induced volume depletion stimulates antidiuretic hormone release, causing free water retention that dilutes serum sodium; elderly women are particularly susceptible due to lower muscle mass reducing total body solute; serum sodium should be rechecked within 2 to 4 weeks of initiation or dose increase

Rationale

Thiazide diuretics cause natriuresis but do not inhibit free water reabsorption in the collecting duct. The resulting volume depletion stimulates antidiuretic hormone (also called vasopressin) release from the posterior pituitary. Antidiuretic hormone promotes free water reabsorption in the collecting duct, diluting the remaining sodium and producing hyponatremia. Unlike loop diuretics — which also block the concentrating capacity of the thick ascending limb and limit antidiuretic hormone's effectiveness — thiazides act distally and do not impair antidiuretic hormone-mediated water reabsorption, making them particularly prone to causing hyponatremia. Elderly women are at elevated risk for two reasons: lower baseline muscle mass means less total body solute to buffer the dilutional effect, and estrogen sensitizes the hypothalamic thirst center and antidiuretic hormone response. Serum sodium must be rechecked within 2 to 4 weeks of initiating or increasing a thiazide in elderly patients — hyponatremia can be severe enough to cause confusion, seizures, and life-threatening complications if undetected.

Correct Answer

C — Reduce or withdraw antihypertensive medications — in frail elderly patients experiencing falls and orthostatic hypotension attributable to over-treatment, the benefit-risk calculation favors reducing therapy to improve quality of life and functional status

Rationale

This patient's clinical picture — supine blood pressure of 108/62 falling to 84/50 on standing, with recurrent falls and weakness — represents antihypertensive over-treatment. In a frail 88-year-old, the benefit-risk calculation for intensive blood pressure lowering shifts substantially. The absolute cardiovascular benefit of pharmacological blood pressure reduction diminishes with advancing frailty and short life expectancy, while the harms from falls — hip fractures, hospitalization, functional decline, loss of independence — become proportionally more consequential. De-prescribing (the planned and supervised reduction or withdrawal of medications) is appropriate and evidence-supported in this setting. The correct approach is to systematically withdraw or reduce antihypertensives, starting with the agent most likely to be causing orthostatic hypotension (typically an alpha-1 blocker, loop diuretic, or centrally acting agent if present), reassessing functional status and blood pressure at each step. The treatment goal in frail elderly patients shifts toward symptom management, fall prevention, and quality of life rather than cardiovascular event reduction targets designed for non-frail populations.

Correct Answer

B — Thiazide-like diuretics and dihydropyridine calcium channel blockers — elderly isolated systolic hypertension is characteristically low-renin and volume-dependent, making these classes more effective as monotherapy than renin-angiotensin-aldosterone system inhibitors, which are less potent in low-renin states

Rationale

Elderly patients with isolated systolic hypertension typically have low-renin, volume-dependent hypertension driven by arterial stiffness and sodium retention rather than by renin-angiotensin-aldosterone system activation. Thiazide-like diuretics — particularly chlorthalidone and indapamide — reduce volume and address this mechanism directly. They are supported by major outcome trial evidence specifically in elderly isolated systolic hypertension. Dihydropyridine calcium channel blockers such as amlodipine lower systolic blood pressure effectively through arteriolar vasodilation that operates independently of renin-angiotensin-aldosterone system activity, making them equally effective in low-renin states. Renin-angiotensin-aldosterone system inhibitors are less potent as monotherapy in this population precisely because there is less active renin-angiotensin-aldosterone system to inhibit — they achieve better results when combined with a diuretic or calcium channel blocker, or when a compelling indication such as chronic kidney disease with proteinuria, heart failure, or diabetic nephropathy is present. Beta-adrenergic receptor antagonists are also less effective for systolic blood pressure reduction in elderly isolated systolic hypertension and are not preferred unless a compelling indication exists.

Correct Answer

D — Chlorthalidone-induced volume depletion triggers antidiuretic hormone release, causing free water retention in the collecting duct that dilutes serum sodium; elderly women are especially vulnerable because lower lean body mass reduces total body sodium stores

Rationale

Chlorthalidone blocks the sodium-chloride cotransporter in the distal convoluted tubule, causing natriuresis. However, it does not block free water reabsorption in the collecting duct — that capacity remains intact and is governed by antidiuretic hormone. The volume depletion caused by natriuresis is sensed by hypothalamic osmoreceptors and baroreceptors, which trigger antidiuretic hormone release from the posterior pituitary. Antidiuretic hormone promotes free water reabsorption in the collecting duct through aquaporin channels, expanding intravascular volume but diluting the remaining sodium — the classic dilutional hyponatremia. This is why thiazides (and thiazide-like agents) cause hyponatremia while loop diuretics, which block the thick ascending limb and impair the countercurrent concentrating mechanism, generally do not. Elderly women are at particular risk for two reasons: lower lean body mass reduces total body solute available to buffer the dilutional effect, and estrogen enhances antidiuretic hormone sensitivity. A serum sodium of 126 mEq/L with neurological symptoms (confusion) requires prompt management — the immediate step is to hold chlorthalidone and address fluid and sodium balance, with cautious monitoring of sodium correction to avoid osmotic demyelination.

Correct Answer

A — Systematically reduce or withdraw antihypertensives starting with the agents most likely to cause orthostatic hypotension — the benefit-risk calculation in a very frail patient experiencing falls has shifted toward reducing medication burden and improving functional status

Rationale

This patient's blood pressures — 102/58 supine dropping to 78/44 standing — and his recurrent falls represent antihypertensive over-treatment in a very frail elderly man. A Clinical Frailty Scale score of 7 indicates severe frailty, and the evidence base for intensive blood pressure targets was derived from trials that excluded or underrepresented patients with this degree of frailty. In frail elderly patients, the absolute cardiovascular benefit of tight blood pressure control is diminished, while the harms — falls, hip fractures, hospitalization, and loss of independence — become dominant clinical concerns. The appropriate approach is de-prescribing: systematically reducing or withdrawing antihypertensives in a planned, supervised manner, starting with agents most likely to cause orthostatic hypotension such as alpha-1 blockers, loop diuretics, and centrally acting agents. The blood pressure target should be individualized, and for very frail patients, avoiding symptomatic hypotension and falls takes priority over achieving a specific numerical goal. This approach is not abandoning care — it is recognizing that quality of life and functional independence are the appropriate primary outcomes in this patient.

Correct Answer

C — Reducing diastolic pressure to 58 millimeters of mercury has impaired coronary perfusion in territories supplied by the stented vessels — coronary arteries fill during diastole, and below approximately 65 to 70 millimeters of mercury in a patient with coronary artery disease, perfusion pressure may be insufficient to maintain adequate myocardial blood flow

Rationale

This case illustrates the J-curve phenomenon — the observation that at very low diastolic blood pressures, cardiovascular events paradoxically increase despite lower overall blood pressure. The mechanism is physiologically straightforward: unlike most organs, the heart receives the majority of its blood supply during diastole, when the myocardium relaxes and intramural vascular compression is absent. The driving pressure for coronary filling is aortic diastolic pressure. In patients with normal coronary arteries, autoregulation maintains myocardial perfusion across a wide range of perfusion pressures. In patients with coronary artery disease — including stented vessels with residual luminal irregularities or regions of microvascular disease — the autoregulatory reserve is reduced, and perfusion becomes more dependent on driving pressure. When diastolic blood pressure falls below approximately 65 to 70 millimeters of mercury in such a patient, coronary perfusion in vulnerable territories may fall below the threshold for adequate oxygen delivery, particularly during exercise when demand increases. The appropriate pharmacological response is to accept a higher systolic blood pressure target in this patient — reducing antihypertensive intensity to restore diastolic pressure to a safer range — rather than continuing to chase a systolic target at the expense of coronary perfusion.