Antihypertensive Drugs Quiz

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Questions and Answers

Which antihypertensive drug group primarily works on the sympathetic nervous system?

Vasodilators

Sympathoplegic agents (correct)

Diuretics

Angiotensin antagonists

What is a major characteristic of hypertension emergencies?

Dietary sodium restriction

Severe hypertension with organ damage (correct)

High levels of physical activity

Normal blood pressure readings

How does aerobic physical activity benefit blood pressure?

Eliminates the need for medication

Reduces the risk of obesity only

Can lower systolic blood pressure by 4-9 mm Hg (correct)

Increases diastolic blood pressure

What is a primary action of loop diuretics like furosemide?

Inhibit the Na+/K+/Cl- cotransporter in the ascending limb of the loop of Henle Signup and view all the answers

Which condition is NOT a common side effect of loop diuretics?

Hypercalcemia Signup and view all the answers

Why are potassium-sparing diuretics often used alongside ACE inhibitors?

To decrease renal potassium excretion and avoid hypokalemia Signup and view all the answers

In which patient situation are loop diuretics particularly effective?

Patients with severe edema and renal insufficiency Signup and view all the answers

What is a primary effect of clonidine on the central nervous system?

Inhibits sympathetic cardiovascular center Signup and view all the answers

Which statement is true regarding thiazide diuretics compared to loop diuretics?

Thiazide diuretics maintain effectiveness in patients with normal renal function. Signup and view all the answers

What serious side effect is associated with clonidine use?

Rebound hypertension Signup and view all the answers

Which of the following correctly represents the pathway of the angiotensin system starting from angiotensinogen?

Angiotensinogen → Renin → Angiotensin I → ACE → Angiotensin II Signup and view all the answers

What is the effect of activating AT1 receptors?

Increased intracellular calcium levels leading to vasoconstriction Signup and view all the answers

What role do ACE inhibitors play in the renin-angiotensin system?

They inhibit the conversion of Angiotensin I to Angiotensin II Signup and view all the answers

Which of the following statements about alpha blockers is true?

Prazosin a main alpha receptor blocker can cause reflex sympathetic activity. Signup and view all the answers

What is a prominent side effect of non-selective beta-adrenergic blockers?

Bronchospasm in asthmatics Signup and view all the answers

Which of the following agents is a mixed alpha and beta-adrenergic blocker?

Labetalol Signup and view all the answers

What is a disadvantage of using prazosin as a treatment?

Can lead to orthostatic hypotension. Signup and view all the answers

Which effect is characteristic of beta-adrenergic blockers like propranolol?

Decreased heart rate and myocardial oxygen consumption Signup and view all the answers

What distinguishes the two types of angiotensin antagonists (Captropril & Losartan)?

The specific receptors they block. Signup and view all the answers

Which drug is considered a major vasodilator used in antihypertensive treatment?

Hydralazine Signup and view all the answers

What is a potential consequence of using prazosin as a treatment for hypertension?

Increased oxygen demand due to reflex sympathetic activity. Signup and view all the answers

Why are loop diuretics like furosemide less effective in hypertensive patients with normal renal function compared to thiazide diuretics?

Their antihypertensive effects are not strong. Signup and view all the answers

What effect do potassium-sparing diuretics have in contrast to thiazide and loop diuretics?

They prevent hypokalemia by decreasing renal potassium excretion. Signup and view all the answers

Which drug is considered a selective beta-adrenergic blocker?

Atenolol Signup and view all the answers

What physiological effect do beta-adrenergic blockers have on the heart over chronic use?

Reduction in heart rate and blood pressure lowering myocardial oxygen consumption Signup and view all the answers

What is a significant side effect of clonidine that limits its use as a first-line therapy?

Sedation Signup and view all the answers

Which substance is primarily formed in response to the activation of AT1 receptors?

Aldosterone Signup and view all the answers

How does the renin-angiotensin-aldosterone axis affect blood pressure?

Increases blood pressure by enhancing sodium retention Signup and view all the answers

What role does bradykinin normally play in the vasculature?

Serving as an active vasodilator Signup and view all the answers

What is the effect of activating AT2 receptors in the renin-angiotensin-aldosterone axis?

Increasing cAMP levels Signup and view all the answers

Study Notes

Hypertension Treatment Objectives

Four major groups of antihypertensive drugs and examples for each group need to be listed
Compensatory responses to each of the four major types of antihypertensive drugs should be described
List major sites of action of sympathoplegic drugs. Include examples of drugs acting at each site
List three mechanisms of action of vasodilator drugs
List major antihypertensive vasodilator drugs and describe their effects
Differences between two types of angiotensin antagonists need to be described
Describe pharmacokinetics (PK), pharmacodynamics (PD), and therapeutic use of methyldopa and Aliskiren
List major toxicities of the prototype antihypertensive agents
Explain why some combinations of antihypertensive drugs are rational and appropriate, and why some are not

What Constitutes Hypertension?

Blood pressure (BP) classifications are based on systolic and diastolic readings
Normal BP is less than 120 mmHg systolic and less than 80 mmHg diastolic
Prehypertension ranges from 120-139 mmHg systolic or 80-89 mmHg diastolic
Stage 1 hypertension ranges from 140-159 mmHg systolic or 90-99 mmHg diastolic
Stage 2 hypertension is greater than 160 mmHg systolic or greater than 100 mmHg diastolic
Hypertension emergencies, also known as malignant hypertension, involve severe hypertension coupled with acute end-stage organ damage

How Common is Hypertension?

Approximately 20% of the adult Canadian population has hypertension
The lifetime risk of developing hypertension is approximately 90%

Changes in Systolic & Diastolic BP with Age

Systolic BP generally increases with age in both men and women
Diastolic BP tends to peak in middle age and then decrease in older adults, especially in women

Relative Importance of DBP vs SBP as Predictors of Coronary Heart Disease As a Function of Age

The relative importance of diastolic blood pressure (DBP) and systolic blood pressure (SBP) as predictors of coronary heart disease (CHD) varies with age
In younger individuals, DBP is a stronger predictor of CHD, while in older individuals, SBP is a stronger predictor of CHD

Ethnicity Variations

In African Americans, systolic blood pressure (SBP) is the best predictor of CHD mortality across all age groups
In Caucasians, diastolic blood pressure (DBP) is a significant predictor of CHD in individuals aged 30-39, whereas SBP is the only significant predictor in older age groups

Excess body weight, Excess dietary sodium intake

Molecular pathways explain how excess body weight and sodium intake contribute to hypertension.

Aerobic physical inactivity, Excess alcohol intake

Aerobic exercise can lower systolic blood pressure (SBP)
Excessive alcohol intake is associated with increased angiotensin II (Ang II), vascular inflammation, and endothelial damage

What are the signs and symptoms of hypertension?

Most cases of hypertension are "silent" (asymptomatic)
Malignant hypertension can cause headache, congestive heart failure, stroke, seizures, papilledema (optic disc swelling), renal failure, and anuria

Principal determinants of BP

Arterial pressure = Cardiac Output × Peripheral Resistance

Four Possible Mechanisms for Hypertension

Blood volume, peripheral resistance, venous tone, and cardiac output can contribute to hypertension through various mechanisms and causes.

Four major classes of antihypertensive drugs

Diuretics, sympatholytics, angiotensin inhibitors, and vasodilators are the four major classes of antihypertensive drugs

Three classes of diuretics

Thiazide and related diuretics (e.g., hydrochlorothiazide), loop diuretics (e.g., furosemide), and potassium-sparing diuretics (e.g., spironolactone) are the three main types of diuretics

Short-term effectiveness: inhibit sodium and chloride reabsorption in the distal tubule, leading to sodium and water excretion and decreased blood volume which in turn lowers cardiac output
Long-term effectiveness: reduces sodium content in smooth muscle cells, decreasing muscle sensitivity to vasopressors and lowering peripheral vascular resistance
Pharmacokinetics (PK): effectiveness decreases when glomerular filtration rate (GFR) is low. However they have a protective effect against osteoporosis
Side effects: hypokalemia, hypercalcemia, hyponatremia, hyperglycemia, hyperlipidemia, and hyperuricemia. Lower doses of hydrochlorothiazide can minimize side effects.

Loop diuretics

Less effective than thiazide diuretics for treating hypertension in patients with normal renal function. But they maintain effectiveness in patients with poor renal function.
Mechanism: inhibit sodium, potassium, and chloride cotransporter in the ascending limb of the loop of Henle
Side effects: similar to thiazides (hypokalemia, hyponatremia, hyperglycemia, hyperlipidemia, hyperuricemia)
Use: usually for severe hypertension in emergency or situations with renal insufficiency or edema

Potassium-Sparing Diuretics (e.g., spironolactone)

Have a mild effect on sodium excretion and blood pressure compared to thiazides and loop diuretics.
Decrease renal potassium excretion to prevent hypokalemia.
Use with Caution in patients using ACE inhibitors because both classes increase serum potassium

Sympatholytic drugs (Adrenergic receptor antagonists)

Alpha blockers (e.g., prazosin, terazosin, doxazosin)
Beta blockers (e.g., propranolol, metoprolol, atenolol)
Mixed alpha and beta blockers (e.g., labetalol, carvedilol)
Central sympatholytics (e.g., clonidine)

Alpha 1 adrenergic Blocking Agents (Prazosin)

Mechanism: lowers sympathetic tone on vasculature, dilates arterioles and veins, has less tachycardia compared to many non-selective blockers
Use: not a preferred initial treatment approach due to possible reflex effects.

Beta-adrenergic Drugs (beta-receptor blockers)

Mechanism: blocks beta-adrenergic receptors in the heart and kidneys, reducing cardiac output, myocardial oxygen consumption, and renin release, leading to decreased blood pressure.
Side effects: increased triglycerides, decreased HDL, glucose intolerance, impotence, depression, and not suitable for people prone to bronchospasm

Mixed Alpha- and beta-adrenergic Blocking Agents (labetalol)

Mechanism: blocks both alpha and beta receptors. Has no tachycardia. Relatively safe.
Use: very effective IV antihypertensive and less frequent use as a chronic oral agent, frequently used for emergencies.

Centrally acting adrenergic drugs (Clonidine)

Mechanism: stimulates CNS alpha2 receptors, inhibits cardiovascular and vasoconstrictor centers, decreasing sympathetic outflow from the CNS.
Use: effective but usually not a first-line therapy, used primarily for patients resistant to other medications due to side effects including sedation and rebound hypertension

Angiotensin Antagonists

ACE inhibitors (e.g., "-pril" drugs like captopril): inhibit angiotensin-converting enzyme (ACE), reducing Ang II levels, Aldosterone, and increasing bradykinin.
ARBs (e.g., "-sartan" drugs like losartan): block angiotensin II receptors (AT1), reducing vasoconstriction and aldosterone release

Mechanism of ACE Inhibitors (general)

Reduces blood levels of Ang II and aldosterone
Increases endogenous vasodilators like bradykinin by inhibiting its degradation
Reduces peripheral vascular resistance, sodium retention, and increases hyperkalemia.

Mechanism of AT1-receptor inhibitors

Mechanism: inhibits AT1 receptors in vascular smooth muscle and adrenal cortex, resulting in vasodilation and decreased aldosterone secretion.

AT1-receptor antagonist

Similar efficiency to ACE inhibitors as an antihypertensive therapy
Interactions with other drugs such as cimetidine and phenobarbital may impact levels of the AT1-inhibitor
Contraindications; similar to ACE inhibitors.
Side effects; similar to ACE inhibitors, including hyperkalemia but rarely causes chronic cough, well tolerated by most patients

What is Methyldopa?

Methyldopa is a medication used to treat hypertension

Mechanism of Action of Vasodilators

Reduction of calcium influx (e.g., calcium channel blockers)
Increasing potassium permeability (e.g., Minoxidil Sulfate, diazoxide)
Release of nitric oxide (e.g., hydralazine, nitroprusside, nitrates)
Dopamine receptor activation (e.g., fenoldopam)

Side effects & toxicity of direct vasodilators

Oral agents: tachycardia, palpitations, angina, sweating, headache, edema
Parenteral agents: excessive hypotension
Calcium channel blockers: cardiac depression = decreased heart rate and decreased output

Compensatory Mechanisms

Reflex tachycardia
Fluid retention by the kidneys
Activation of the renin-angiotensin-aldosterone axis

Management of Hypertension: Recommendations

Diuretics or calcium channel blockers, ACE inhibitors are first-line treatments for most patients.
Beta-blockers are often recommended for younger patients (<60), patients with stable angina, systolic heart dysfunction, or post-myocardial infarction (MI)
ACE inhibitors, calcium channel blockers, or alpha-adrenergic receptor antagonists may be used as alternatives if diuretics or beta-blockers aren't suitable

Multiple Drug Therapy

If a single drug doesn’t adequately control blood pressure, another antihypertensive medication can be added
Drugs are usually added gradually over a few weeks
Combination therapy may be necessary for severe hypertension, particularly in patients with target organ damage

Effective Combinations

ACE inhibitor-diuretic combinations, beta-blocker-diuretic combinations, alpha-blocker-diuretic combinations, calcium antagonist-ACE inhibitor combinations, and angiotensin II receptor antagonist-diuretic combinations are all examples of effective hypertension combinations.

CAUTION: Multiple Drug Combinations

Not all drug combinations are safe
Combining certain medications can have unexpected effects like paradoxical increases in blood pressure

Management of Hypertension (Table)

Table outlines initial antihypertensive therapy recommendations based on blood pressure classifications

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Description

Test your knowledge on antihypertensive drug classes, their mechanisms, and effects. This quiz covers topics including the sympathetic nervous system's role in hypertension, diuretics, and key characteristics of various antihypertensive agents. Perfect for nursing or pharmacology students.