Download Diuretics & 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
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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
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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
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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:
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
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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
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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
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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:
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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
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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