Transcript Antihypertensive Agents Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.

Antihypertensive Agents
Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
Hypertension
High blood pressure
• Normal:
Systolic < 130 mm
Hg Diastolic < 85 mm Hg
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Classification of Blood Pressure
Category
Systemic BP (mm Hg)
Diastolic BP (mm Hg)
Normal
<130
<85
High normal
130-139
85-89
Hypertension
Stage 1
Stage 2
Stage 3
Stage 4
140-159
160-169
180-209
 210
90-99
100-109
110-119
 120
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Classification of Blood Pressure
Primary Hypertension
• Specific cause unknown
• 90% of the cases
• Also known as essential or idiopathic hypertension
Secondary Hypertension
• Cause is known (such as eclampsia of pregnancy,
renal artery disease, pheochromocytoma)
• 10% of the cases
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Blood Pressure = CO x SVR
• CO = Cardiac output
• SVR = Systemic vascular resistance
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Instructors may want to insert
EIC Image #69:
Blood Pressure: Normal Regulation
Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
Antihypertensive Agents
• Medications used to treat hypertension
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Antihypertensive Agents: Categories
• Adrenergic agents
• Angiotensin-converting enzyme inhibitors
• Angiotensin II receptor blockers
• Calcium channel blockers
• Diuretics
• Vasodilators
Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
Antihypertensive Agents: Categories
• Adrenergic Agents
– Alpha1 blockers
– Beta blockers (cardioselective and nonselective)
– Centrally acting alpha blockers
– Combined alpha-beta blockers
– Peripheral-acting adrenergic agents
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Antihypertensive Agents:
Mechanism of Action
Adrenergic Agents
Alpha1 Blockers (peripherally acting)
• Block the alpha1-adrenergic receptors
• The SNS is not stimulated
Result: DECREASED blood pressure
• Stimulation of alpha1-adrenergic receptors
causes HYPERtension
• Blocking alpha1-adrenergic receptors causes
decreased blood pressure
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Antihypertensive Agents:
Adrenergic Agents
Alpha1 Blockers
• doxazosin (Cardura)
• prazosin (Minipress)
• terazosin (Hytrin)
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Antihypertensive Agents:
Mechanism of Action
Adrenergic Agents
Central-Acting Adrenergics
• Stimulate alpha2-adrenergic receptors
• Sympathetic outflow from the CNS is decreased
Result: decreased blood pressure
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Antihypertensive Agents:
Adrenergic Agents
Central-Acting Adrenergics
• clonidine (Catapres)
• methyldopa (Aldomet)
(drug of choice for hypertension in pregnancy)
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Antihypertensive Agents:
Mechanism of Action
Adrenergic Agents
Adrenergic Neuronal Blockers
(peripherally acting)
• Inhibit release of norepinephrine
• Also deplete norepinephrine stores
• SNS (peripheral adrenergic nerves) is not stimulated
Result: decreased blood pressure
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Antihypertensive Agents:
Adrenergic Agents
Adrenergic Neuronal Blockers
(peripherally acting)
• reserpine
• guanadrel (Hylorel)
• guanethidine (Ismelin)
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Antihypertensive Agents:
Adrenergic Agents
Therapeutic Uses
• Alpha1 blockers (peripherally acting)
– Treatment of hypertension
– Relief of symptoms of BPH
– Management of of severe CHF when used
with cardiac glycosides and diuretics
Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
Antihypertensive Agents:
Adrenergic Agents
Therapeutic Uses
• Central-Acting Adrenergics
– Treatment of hypertension, either alone or
with other agents
– Usually used after other agents have failed
due to side effects
– Also may be used for treatment of severe
dysmenorrhea, menopausal flushing, glaucoma
– Clonidine is useful in the management of
withdrawal symptoms in opioid- or nicotinedependent persons
Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
Antihypertensive Agents:
Adrenergic Agents
Therapeutic Uses
• Adrenergic neuronal blockers
(peripherally acting)
– Treatment of hypertension, either alone or with
other agents
– Seldom used because of frequent side effects
Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
Antihypertensive Agents:
Adrenergic Agents
Side Effects
Most common:
dry mouth
sedation
drowsiness
constipation
Other:
headaches
sleep disturbances
nausea
rash
cardiac disturbances (palpitations)
HIGH INCIDENCE OF ORTHOSTATIC HYPOTENSION
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Antihypertensive Agents:
Categories
Angiotensin-Converting Enzyme Inhibitors
(ACE Inhibitors)
• Large group of safe and effective drugs
• Often used as first-line agents for CHF
and hypertension
• May be combined with a thiazide diuretic
or calcium channel blocker
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Antihypertensive Agents:
Mechanism of Action
ACE Inhibitors
RAAS: Renin Angiotensin-Aldosterone System
• When the enzyme angiotensin I is converted to
angiotensin II, the result is potent vasoconstriction
and stimulation of aldosterone
• Result of vasoconstriction: increased systemic
vascular resistance and increased afterload
• Therefore, increased BP
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Antihypertensive Agents:
Mechanism of Action
ACE Inhibitors
• Aldosterone stimulates water and sodium resorption.
• Result: increased blood volume, increased preload,
and increased B
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Antihypertensive Agents:
Mechanism of Action
ACE Inhibitors
• ACE Inhibitors block the angiotensin-converting
enzyme, thus preventing the formation of
angiotensin II.
• Also prevent the breakdown of the vasodilating
substance, bradykinin
Result: decreased systemic vascular resistance (afterload),
vasodilation, and therefore, decreased blood pressure
Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
Antihypertensive Agents
ACE Inhibitors
• captopril (Capoten)
• Short half-life, must be dosed more frequently
than others
• enalapril (Vasotec)
• The only ACE inhibitor available in oral and
parenteral forms
• lisinopril (Prinivil and Zestril) and quinapril (Accupril)
• Newer agents, long half-lives, once-a-day dosing
• Several other agents available
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Antihypertensive Agents:
Therapeutic Uses
ACE Inhibitors
• Hypertension
• CHF (either alone or in combination with diuretics
or other agents)
• Slows progression of left ventricular hypertrophy
after an MI
• Renal protective effects in patients with diabetes
Drugs of choice in hypertensive patients with CHF
Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
Antihypertensive Agents:
Side Effects
ACE Inhibitors
• Fatigue
Dizziness
• Headache
Mood changes
• Impaired taste
Dry, nonproductive cough, reverses when therapy is stopped
NOTE: first-dose hypotensive effect may occur!!
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Antihypertensive Agents:
Categories
Angiotensin II Receptor Blockers
(A II Blockers or ARBs)
• Newer class
• Well-tolerated
• Do not cause coughing
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Antihypertensive Agents:
Mechanism of Action
Angiotensin II Receptor Blockers
• Allow angiotensin I to be converted to angiotensin II,
but block the receptors that receive angiotensin II
• Block vasoconstriction and release of aldosterone
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Antihypertensive Agents:
Angiotensin II Receptor Blockers
• losartan (Cozaar)
• eposartan (Teveten)
• valsartan (Diovan)
• irbesartan (Avapro)
• candesartan (Atacand)
• telmisartan (Micardis)
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Antihypertensive Agents:
Therapeutic Uses
Angiotensin II Receptor Blockers
• Hypertension
• Adjunctive agents for the treatment of CHF
• May be used alone or with other agents such
as diuretics
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Antihypertensive Agents:
Side Effects
Angiotensin II Receptor Blockers
• Upper respiratory infections
• Headache
• May cause occasional dizziness, inability to sleep,
diarrhea, dyspnea, heartburn, nasal congestion,
back pain, fatigue
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Antihypertensive Agents:
Categories
Calcium Channel Blockers
• Benzothiazepines
• Dihydropyridines
• Phenylalkylamines
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Antihypertensive Agents:
Mechanism of Action
Calcium Channel Blockers
• Cause smooth muscle relaxation by blocking the
binding of calcium to its receptors, preventing
muscle contraction
• This causes decreased peripheral smooth muscle
tone, decreased systemic vascular resistance
• Result: decreased blood pressure
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Antihypertensive Agents
Calcium Channel Blockers
• Benzothiazepines:
– diltiazem (Cardizem, Dilacor)
• Phenylalkamines:
– verapamil (Calan, Isoptin)
• Dihydropyridines:
– amlodipine (Norvasc), bepridil (Vascor),
nicardipine (Cardene)
– nifedipine (Procardia), nimodipine (Nimotop)
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Antihypertensive Agents:
Therapeutic Uses
Calcium Channel Blockers
• Angina
• Hypertension
• Dysrhythmias
• Migraine headaches
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Antihypertensive Agents:
Side Effects
Calcium Channel Blockers
• Cardiovascular
– hypotension, palpitations, tachycardia
• Gastrointestinal
– constipation, nausea
• Other
– rash, flushing, peripheral edema, dermatitis
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Antihypertensive Agents: Diuretics
• Decrease the plasma and extracellular fluid volumes
• Results:
decreased preload
decreased cardiac output
decreased total peripheral resistance
• Overall effect: decreased workload of the heart,
and decreased blood pressure
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Antihypertensive Agents:
Mechanism of Action
Vasodilators
• Directly relaxes arteriolar smooth muscle
• Result:
decreased systemic vascular response,
decreased afterload, and
PERIPHERAL VASODILATION
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Antihypertensive Agents
Vasodilators
• diazoxide (Hyperstat)
• hydralazine HCl (Apresoline)
• minoxidil (Loniten, Rogaine)
• sodium nitroprusside (Nipride, Nitropress)
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Antihypertensive Agents:
Therapeutic Uses
Vasodilators
• Treatment of hypertension
• May be used in combination with other agents
• Sodium nitroprusside and diazoxide IV are reserved
for the management of hypertensive emergencies
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Antihypertensive Agents: Side
Effects
Vasodilators
• Hydralazine:
– dizziness, headache, anxiety, tachycardia,
nausea and vomiting, diarrhea, anemia,
dyspnea, edema, nasal congestion
• Sodium nitroprusside:
– bradycardia, hypotension, possible
cyanide toxicity
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Antihypertensive Agents:
Nursing Implications
• Before beginning therapy, obtain a thorough
health history and head-to-toe physical
examination.
• Assess for contraindications to specific
antihypertensive agents.
• Assess for conditions that require cautious
use of these agents.
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Antihypertensive Agents:
Nursing Implications
• Educate patients about the importance of not
missing a dose and taking the medications exactly
as prescribed.
• Patients should never double up on doses if a dose
is missed; check with physician for instructions on
what to do if a dose is missed.
• Monitor BP during therapy. Instruct patients to
keep a journal of regular BP checks.
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Antihypertensive Agents:
Nursing Implications
• Instruct patients that these drugs should not be
stopped abruptly, as this may cause a rebound
hypertensive crisis, and perhaps lead to CVA.
• Oral forms should be given with meals so that
absorption is more gradual and effective.
• Administer IV forms with extreme caution and
use an IV pump.
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Antihypertensive Agents:
Nursing Implications
• Remind patients that medications is only part of
therapy. Encourage patients to watch their diet,
stress level, weight, and alcohol intake.
• Patients should avoid smoking and eating foods
high in sodium.
• Encourage supervised exercise.
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Antihypertensive Agents:
Nursing Implications
• Instruct patients to change positions slowly to avoid
syncope from postural hypotension.
• Patients should report unusual shortness of breath;
difficulty breathing; swelling of the feet, ankles, face,
or around the eyes; weight gain or loss; chest pain;
palpitations; or excessive fatigue.
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Antihypertensive Agents:
Nursing Implications
• Men taking these agents may not be aware that
impotence is an expected effect. This may influence
compliance with drug therapy.
• If patients are experiencing serious side effects,
or believe that the dose or medication needs to
be changed, they should contact their physician
immediately.
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Antihypertensive Agents:
Nursing Implications
• Hot tubs, showers, or baths; hot weather; prolonged
sitting or standing; physical exercise; and alcohol
ingestion may aggravate low blood pressure,
leading to fainting and injury. Patients should
sit or lie down until symptoms subside.
• Patients should not take any other medications,
including OTC drugs, without first getting the
approval of their physician.
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Antihypertensive Agents:
Nursing Implications
• Monitor for side/adverse effects
(dizziness, orthostatic hypotension, fatigue)
and for toxic effects.
• Monitor for therapeutic effects
• Blood pressure should be maintained at less
than 140/90 mm Hg
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