Chapter 20 Diuretics and Antihypertensives Diuretics and Antihypertensives

Diuretics and Antihypertensives Diuretics l £ Remove sodium and water u Remove extracellular fluid

Classifications Thiazide diuretics Loop diuretics Potassium-sparing diuretics Osmotic diuretics Carbonic anhydrase inhibitors Combination potassium-sparing

Excess Fluid Removal of excess fluid results in: l £ £ £ 4 Decreased

(continued) Excess Fluid Overall effect l £ Decreased workload of the heart, and decreased

Thiazide Diuretics Primary site of action l £ Renal distal convoluted tubule u Sodium

Thiazide Diuretics: Side Effects Loss of potassium Loss of sodium and chloride Hyperglycemia: high

Thiazide Diuretics Safe Require supplements l l £ Potassium chloride u Administered as tablets,

Loop Diuretics Furosemide (Lasix) l £ Works directly on the ascending limb of the

Loop Diuretics: Side Effects Dry mouth Potassium depletion (hypokalemia) Hearing loss Fatigue Dehydration Hypotension

Potassium-Sparing Diuretics Inhibit aldosterone l £ Example: spironolactone Weak action: They competitively bind to

Osmotic Diuretics l Action £ l l Produce a profound diuretic effect Used to

Carbonic Anhydrase Inhibitors l Carbonic anhydrase £ Normal enzyme found in the body u

Combination Potassium-Sparing and Hydrochlorothiazide Diuretics Decreases adverse effects l £ £ Hypokalemia from thiazides

Hypertension An abnormal increase in arterial blood pressure l 15 Copyright 2007 Thomson Delmar

Blood Pressure CO = cardiac output SVR = systemic vascular resistance Normal blood pressure

Antihypertensives l l l l Diuretics Central-acting antiadrenergics Peripherally acting antiadrenergics Beta-adrenergic blocking agents

Diuretics and Antihypertensives l Effective control of blood pressure £ Diuretics frequently given in

ACE Inhibitors Action: antagonists to the renin angiotensin-aldosterone system ACE inhibitors prevent: l l

(continued) ACE Inhibitors Result of vasodilation: decreased blood pressure, decreased systemic vascular resistance, and

ACE Inhibitors: Side Effects Fatigue Dizziness Headache Mood changes Impaired taste Dry, nonproductive cough

Angiotensin II Antagonists Allow angiotensin I to be converted to angiotensin II, but block

Calcium Channel Blockers l Mechanism of action £ £ Dilate peripheral arterioles and reduce

Calcium Channel Blockers: Side Effects l l Hypotension, palpitations, tachycardia Rash, flushing, peripheral edema,

Beta-adrenergic Blocking Agents l l Inhibit beta 1 and beta 2 receptors in the

Vasodilators Directly dilates the peripheral arterioles l £ Lowers the blood pressure 26 Copyright

Peripherally Acting Antiadrenergic Agents l Two main actions £ Deplete norepinephrine u £ Adverse

Central-Acting Antiadrenergics Action not clear l £ £ Theory 1: replaces norepinephrine in adrenergic

Central-Acting Antiadrenergics: Side Effects l General side effect £ High incidence of orthostatic hypotension

Central-Acting Antiadrenergics: Client Teaching Instruct clients l £ Do not stop abruptly. u £

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Chapter 20 Diuretics and Antihypertensives

Diuretics and Antihypertensives Diuretics l £ Remove sodium and water u Remove extracellular fluid (edema) Antihypertensives l £ Lower blood pressure Both diuretics and antihypertensives l £ Used to treat hypertension 2 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

Classifications Thiazide diuretics Loop diuretics Potassium-sparing diuretics Osmotic diuretics Carbonic anhydrase inhibitors Combination potassium-sparing and hydrochlorothiazide diuretics l l l 3 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

Excess Fluid Removal of excess fluid results in: l £ £ £ 4 Decreased preload Decreased cardiac output Decreased total peripheral resistance (continues) Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

(continued) Excess Fluid Overall effect l £ Decreased workload of the heart, and decreased blood pressure 5 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

Thiazide Diuretics Primary site of action l £ Renal distal convoluted tubule u Sodium and chloride • • £ Normal Reabsorbed Drug agents u Excreted 6 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

Thiazide Diuretics: Side Effects Loss of potassium Loss of sodium and chloride Hyperglycemia: high blood sugar Hyperuricemia: high uric acid Skin rash l l l 7 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

Thiazide Diuretics Safe Require supplements l l £ Potassium chloride u Administered as tablets, capsules, IV, liquids, and effervescent solutions Teaching l £ Encourage the client to eat oranges and bananas 8 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

Loop Diuretics Furosemide (Lasix) l £ Works directly on the ascending limb of the loop of Henle u £ Inhibits sodium and chloride reabsorption More potent than thiazides 9 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

Loop Diuretics: Side Effects Dry mouth Potassium depletion (hypokalemia) Hearing loss Fatigue Dehydration Hypotension l l l 10 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

Potassium-Sparing Diuretics Inhibit aldosterone l £ Example: spironolactone Weak action: They competitively bind to aldosterone receptors and block the reabsorption of sodium and water. l £ Conserve potassium 11 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

Osmotic Diuretics l Action £ l l Produce a profound diuretic effect Used to treat intracranial pressure and renal failure Example £ Mannitol 12 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

Carbonic Anhydrase Inhibitors l Carbonic anhydrase £ Normal enzyme found in the body u Promotes reabsorption of sodium and bicarbonate from the renal nephrons’ proximal tubule • • l Maintains alkalinity of the blood Normal blood p. H 7. 35 to 7. 45 Very weak diuretic £ Treat glaucoma 13 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

Combination Potassium-Sparing and Hydrochlorothiazide Diuretics Decreases adverse effects l £ £ Hypokalemia from thiazides Hyperkalemia from potassium-sparing diuretics 14 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

Blood Pressure CO = cardiac output SVR = systemic vascular resistance Normal blood pressure l l l £ £ Systolic < 120 mm Hg Diastolic < 80 mm Hg 16 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

Antihypertensives l l l l Diuretics Central-acting antiadrenergics Peripherally acting antiadrenergics Beta-adrenergic blocking agents Vasodilators Angiotensin-converting enzyme inhibitors Angiotensin II antagonists Calcium channel blockers 17 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

Diuretics and Antihypertensives l Effective control of blood pressure £ Diuretics frequently given in combination with another class of antihypertensives 18 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

ACE Inhibitors Action: antagonists to the renin angiotensin-aldosterone system ACE inhibitors prevent: l l £ 19 Angiotensin I conversion to angiotensin II; angiotensin II produces potent vasoconstriction and stimulation of aldosterone (continues) Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

(continued) ACE Inhibitors Result of vasodilation: decreased blood pressure, decreased systemic vascular resistance, and decreased afterload Side effect: cough l l 20 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

ACE Inhibitors: Side Effects Fatigue Dizziness Headache Mood changes Impaired taste Dry, nonproductive cough l l l 21 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

Angiotensin II Antagonists Allow angiotensin I to be converted to angiotensin II, but block the receptors that receive angiotensin II l £ £ Block vasoconstriction and release of aldosterone Lower blood pressure Well-tolerated l £ Coughing not a concern 22 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

Calcium Channel Blockers l Mechanism of action £ £ Dilate peripheral arterioles and reduce peripheral resistance Reduce arterial blood pressure at rest and during exercise 23 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

Calcium Channel Blockers: Side Effects l l Hypotension, palpitations, tachycardia Rash, flushing, peripheral edema, dermatitis 24 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

Beta-adrenergic Blocking Agents l l Inhibit beta 1 and beta 2 receptors in the heart and the lung, or just the heart Reduce £ £ l Heart rate Force of contraction Adverse effect £ Bronchoconstriction 25 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

Peripherally Acting Antiadrenergic Agents l Two main actions £ Deplete norepinephrine u £ Adverse effect: depression Block adrenergic receptors u u Prevent sympathetic nervous system stimulation Adverse effect: hypotension 27 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

Central-Acting Antiadrenergics Action not clear l £ £ Theory 1: replaces norepinephrine in adrenergic storage sites Theory 2: sympathetic outflow from the central nervous system is decreased u Epinephrine and norepinephrine is decreased Adverse effect l £ Sedation 28 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

Central-Acting Antiadrenergics: Side Effects l General side effect £ High incidence of orthostatic hypotension u Instruct clients to change positions slowly 29 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

Central-Acting Antiadrenergics: Client Teaching Instruct clients l £ Do not stop abruptly. u £ £ Rebound hypertensive crisis Oral forms should be given with meals so that absorption is more gradual and effective. Administer IV forms with caution. u Use an IV pump. 30 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.