Diuretics and Antihypertensives Chapter 20 Diuretics and Antihypertensives

Diuretics and Antihypertensives p482 Diuretics used to treat edema, ascites, HTN Remove sodium and water from circulation Antihypertensives: lower blood pressure Both diuretics and antihypertensives Used to treat hypertension (HTN)

Classifications of diuretics p483 Thiazide diuretics Loop diuretics Potassium-sparing diuretics Osmotic diuretics Carbonic anhydrase inhibitors Combination potassium-sparing and hydrochlorothiazide diuretics

Thiazide Diuretics p483 Primary site of action Renal distal convoluted tubule Prevents sodium and chloride reabsorption into circulation Prototype: hydrochlorothiazide (HCTZ)

Thiazide Diuretics: Side Effects p483 Loss of potassium Loss of sodium and chloride Hyperglycemia: high blood sugar Hyperuricemia: high uric acid Skin rash

Thiazide Diuretics p483 Safe Require supplements Potassium chloride Administered as tablets, capsules, IV, liquids, and effervescent solutions Teaching Encourage the client to eat oranges, apricots, and bananas for K+ in diet Signs/symptoms of hypokalemia, hyponatremia Take diuretics in the morning for once a day dose. If twice a day dose, take second dose no later than 6pm.

Loop Diuretics p485 Prototype: furosemide (Lasix) Works directly on the ascending limb of the loop of Henle Inhibits sodium and chloride reabsorption More potent than thiazides Remain effective even in pt with seriously impaired glomerular filtration rates

Loop Diuretics: Side Effects p485 Dry mouth Hypokalemia Hearing loss Fatigue Dehydration Hypotension

Symptoms of hypokalemia p504 Pulse irregularities, irregular HR Leg cramps General muscle weakness

Symptoms of hyponatremia p503 Weakness Confusion Abdominal cramps Muscle twitching If severe, seizures may occur

Potassium-Sparing Diuretics p485 Inhibit action of aldosterone (produced by adrenal cortex) or block Na+ reabsorption in distal tubule Example: spironolactone, triamterene Conserve potassium Pt teaching: do not eat diet high in K+

Osmotic Diuretics p485 Action: Produce a profound diuretic effect by a high concentration of osmotic agent in the kidney tubule. Used to treat increased intracranial pressure and acute renal failure Example Mannitol

Carbonic Anhydrase Inhibitors p485 Examples: acetazolamide methazolamide Very weak diuretic effect Treats glaucoma: reduces the rate of production of aqueous humor in the eye

Combination Potassium-Sparing and Hydrochlorothiazide Diuretics p 485 Decreases adverse effects of each of the diuretic components Decreases hypokalemia from thiazides Decreases hyperkalemia from potassium-sparing diuretics Examples: Aldactazide HCTZ and spironolactone Dyazide HCTZ and triamterene

Hypertension p488 An abnormal increase in arterial blood pressure

Blood Pressure p488 Blood pressure factors: Normal blood pressure CO = cardiac output PR = peripheral resistance Normal blood pressure Systolic < 120 mm Hg Diastolic < 80 mm Hg

Treatment for hypertension (HTN) p489 Stepped care approach based on cardiovascular risk factors (box 20-1, 20-2, 20-3) Lifestyle modification is always the first step in treating hypertension Weight reduction Exercise program Smoking cessation Reduction of sodium in diet Moderation of alcohol intake

Stepped care approach cont p489-490 If lifestyle modifications do not achieve sufficient reduction in BP, then drug therapy is initiated. Oral diuretics often first drug prescribed

Central-Acting Antiadrenergics p490 Potent antihypertensives. Sympathetic outflow from the central nervous system is decreased Epinephrine and norepinephrine is decreased Adverse effect Sedation Example: clonidine, methyldopa Short acting, must take multiple doses per day

Central-Acting Antiadrenergics p490 General side effect High incidence of orthostatic hypotension Instruct clients to change positions slowly Sedation Instruct clients Do not stop meds abruptly Rebound hypertensive crisis Oral forms should be given with meals so that absorption is more gradual and effective.

Peripherally Acting Antiadrenergic Agents p491 Two main actions Deplete norepinephrine Adverse effect: depression Block adrenergic receptors: Prevent sympathetic nervous system stimulation Adverse effect: hypotension First dose effect: development of significant hypotension and syncope with sudden loss of consciousness with the first few doses or if dosage is increased rapidly Examples: prazosin terazosin doxazosin

Beta-adrenergic Blocking Agents “Beta blockers” p491 Inhibit beta1 and beta2 receptors in the heart and the lungs Best blood pressure lowering result is achieved when given with a diuretic agent Negative inotropic Negative chronotropic Negative dromotropic Prototype: propranolol (Inderal) Adverse effect: bronchoconstriction Hold dose if HR less than 50

Miscellaneous vasodilators p492 Vasodilators directly dilate the peripheral arterioles Hydralazine: dilates peripheral arterioles Side effects: palpitations, tachycardia Minoxidil: dilates peripheral arterioles Side effect: growth and thickening of fine body hair Rogaine is minoxidil in topical dosage form marketed as treatment for male pattern alopecia

Angiotensin-converting enzyme inhibitors p492 Called ACE inhibitors (-pril) Action: antagonists to the renin angiotensin-aldosterone system ACE inhibitors prevent: Angiotensin I conversion to angiotensin II Prototype: Lisinopril

ACE Inhibitors: Side Effects p492 Fatigue Dizziness Headache Mood changes Impaired taste Dry, nonproductive cough Persistent cough could be indication to withdraw Lisinopril Loss of ability to ejaculate, erectile dysfunction

Angiotensin II Antagonists p492 Allow angiotensin I to be converted to angiotensin II, but block the receptors that receive angiotensin II Block vasoconstriction and release of aldosterone Well-tolerated Coughing not a concern Examples irbesartan losartan valsartan

Calcium Channel Blockers p493 Prevent calcium from entering muscle cell thereby reducing muscle contraction Relax peripheral arterioles and reduce peripheral resistance Prototype: verapamil (Calan) Side effects Hypotension palpitations Tachycardia peripheral edema

Hypertensive emergencies p494,500 Diastolic pressure exceeding 120 mm Hg with evidence of end organ damage. Agents for treating hypertensive emergencies: diazoxide nitroprusside sodium

Sodium restriction in diet p502-503 Nurses teach label reading Signs of hyponatremia: weakness confusion abdominal cramps muscle twitching If severe, seizures may occur.

Limiting adverse effects of antihypertensive meds p505 Non-compliance with medication schedule has many causes Do not discontinue the med, but inform health care provider of the side effects so alterations can be made.

Patient teaching Teach pt to take BP daily and keep log Teach at least one family member to take pt BP Smoking cessation Teach signs and symptoms of sodium or potassium depletion Avoid activities that place stress on cardiovascular system. Avoid straining to pass stool Avoid heavy meals Teach lifestyle modifications