Download Pharmacology and the Nursing Process, 4th ed. Lilley/Harrington

Chapter 22
Antihypertensive Drugs
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Blood Pressure

Blood pressure = CO × SVR
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
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CO = cardiac output
SVR = systemic vascular resistance
Hypertension = high blood pressure
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Seventh Report of the Joint National Committee
on Prevention, Detection, Evaluation, and
Treatment of High Blood Pressure (JNC-7)*
Four stages, based on BP measurements
1. Normal
2. Prehypertension
3. Stage 1 hypertension
4. Stage 2 hypertension
*New guidelines pending
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Classification of BP
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Hypertension can also be defined by its cause
Unknown cause
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Essential, idiopathic, or primary hypertension
90% of cases
Known cause
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
Secondary hypertension
10% of cases
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Classroom Response Question
The number of people with hypertension in the
United States is estimated to be:
A. 10 million.
B. 50 million.
C. 75 million.
D. 100 million.
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Autonomic Nervous System
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Parasympathetic nervous system
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Stimulates smooth muscle, cardiac muscle, glands
Sympathetic nervous system
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Stimulates the heart, blood vessels, skeletal muscle
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Location of the Nicotinic Receptors
in the PNS and SNS
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Antihypertensive Drugs
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
Medications used to treat hypertension
Categories
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Adrenergic drugs
 Angiotensin-converting enzyme (ACE) inhibitors
 Angiotensin II receptor blockers (ARBs)
 Calcium channel blockers (CCBs)
 Diuretics
 Vasodilators
 Direct renin inhibitors
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Adrenergic Drugs: Five
Subcategories
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Centrally and peripherally acting adrenergic
neuron blockers
Centrally acting alpha2 receptor agonists
Peripherally acting alpha1 receptor blockers
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Adrenergic Drugs: Five
Subcategories (cont’d)
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Peripherally acting beta receptor blockers
(beta blockers)
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
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Cardioselective (beta1 receptors)
Nonselective (both beta1 and beta2 receptors)
Peripherally acting dual alpha1 and beta receptor
blockers
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Adrenergic Drugs
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Centrally acting alpha2 receptor agonists
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Stimulate alpha2-adrenergic receptors in the brain
 Decrease sympathetic outflow from the CNS
 Decrease norepinephrine production
 Stimulate alpha2-adrenergic receptors, thus reducing
renin activity in the kidneys
 Result in decreased blood pressure
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Adrenergic Drugs (cont’d)
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Centrally acting alpha2 receptor agonists (cont’d)
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
clonidine (Catapres)
methyldopa (Aldomet)
• Can be used for hypertension in pregnancy
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Adrenergic Drugs (cont’d)
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Peripheral alpha1 blockers/antagonists
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Block alpha1-adrenergic receptors
 doxazosin (Cardura)
 terazosin (Hytrin)
 prazosin (Minipress)
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Adrenergic Drugs (cont’d)
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Beta blockers
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Reduce BP by reducing heart rate through beta1
blockade
 Cause reduced secretion of renin
 Long-term use causes reduced peripheral vascular
resistance
 Examples: nebivolol (Bystolic), propranolol (Inderal),
atenolol (Tenormin), others
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Adrenergic Drugs (cont’d)
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Dual-action alpha1 and beta receptor blockers
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Reduce heart rate (beta1 receptor blockade)
 Cause vasodilation (alpha1 receptor blockade)
 carvedilol (Coreg) and labetalol
 Result in decreased blood pressure
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Adrenergic Drugs: Indications
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All used to treat hypertension
Centrally acting alpha2 receptor agonists
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Treatment of hypertension, either alone or
with other drugs
 Usually used after other drugs have failed because of
adverse effects
 Clonidine is useful in the management of withdrawal
symptoms in opioid-dependent persons
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Adrenergic Drugs: Indications
(cont’d)

Peripherally acting alpha1 receptor agonists

Treatment of hypertension
 Some used to relieve symptoms of BPH
• tamsulosin (Flomax)
 Management of severe heart failure (HF) when used
with cardiac glycosides and diuretics
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Adrenergic Drugs:
Adverse Effects
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High incidence of orthostatic hypotension
Most common
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Bradycardia with reflex tachycardia
 Dry mouth
 Drowsiness, sedation
 Constipation
 Depression
 Edema
 Sexual dysfunction
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Adrenergic Drugs:
Adverse Effects (cont’d)

Other
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Headaches
 Sleep disturbances
 Nausea
 Rash
 Cardiac disturbances (palpitations), others
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Classroom Response Question
When administering an alpha-adrenergic drug for
hypertension, it is most important for the nurse to
assess the patient for the development of:
A. hypotension.
B. hyperkalemia.
C. oliguria.
D. respiratory distress.
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Angiotensin-Converting
Enzyme (ACE) Inhibitors
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
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Large group of safe and effective drugs
Often used as first-line drugs for HF
and hypertension
May be combined with a thiazide diuretic or
calcium channel blocker
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ACE Inhibitors (cont’d)
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captopril (Capoten)
benazepril (Lotensin)
enalapril (Vasotec)
fosinopril (Monopril)
lisinopril (Prinivil)
moexipril (Univasc)
quinapril (Accupril)
Others
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ACE Inhibitors:
Mechanism of Action
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Inhibit angiotensin-converting enzyme, which is
responsible for converting angiotensin I (through
the action of renin) to angiotensin II
Angiotensin II is a potent vasoconstrictor and
causes aldosterone secretion from the adrenal
glands
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ACE Inhibitors:
Mechanism of Action (cont’d)
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Block angiotensin-converting enzyme, thus
preventing the formation of angiotensin II
Prevent the breakdown of the vasodilating
substance bradykinin
Result in decreased systemic vascular
resistance (afterload), vasodilation, and
therefore decreased blood pressure
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ACE Inhibitors:
Indications
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Hypertension
HF (either alone or in combination with diuretics
or other drugs)
Slow progression of left ventricular hypertrophy
after MI (cardioprotective)
Renal protective effects in patients with diabetes
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Classroom Response Question
A patient with type II diabetes has a new
prescription for the angiotensin-converting enzyme
(ACE) inhibitor lisinopril. She questions this order
because her physician has never told her that she
has hypertension. What is the best explanation for
this order?
A.
B.
C.
D.
The doctor knows best.
The patient is confused.
This medication has cardioprotective properties.
This medication has a protective effect on the
kidneys for patients with type II diabetes.
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ACE Inhibitors: Indications (cont’d)
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
Drugs of choice in hypertensive patients with HF
Drugs of choice for diabetic patients
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Classroom Response Question
A patient with a history of pancreatitis and cirrhosis
is also being treated for hypertension. Which drug
will most likely be ordered for this patient?
A. clonidine
B. prazosin
C. diltiazem
D. captopril
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ACE Inhibitors (cont’d)
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Captopril and lisinopril are NOT prodrugs
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Prodrugs are inactive in their administered form and
must be metabolized in the liver to an active form so
as to be effective
Captopril and lisinopril can be used if a patient has
liver dysfunction, unlike other ACE inhibitors that are
prodrugs
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ACE Inhibitors: Adverse Effects
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Fatigue
Dizziness
Headache
Mood changes
Impaired taste
Possible hyperkalemia
Dry, nonproductive cough, which reverses when
therapy is stopped
Angioedema: rare but potentially fatal
Note: First-dose hypotensive effect may occur
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Angiotensin II Receptor Blockers
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
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Also referred to as angiotensin II blockers or
ARBs
Well tolerated
Do not cause a dry cough
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Angiotensin II Receptor Blockers
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losartan (Cozaar)
eprosartan (Teveten)
valsartan (Diovan)
irbesartan (Avapro)
candesartan (Atacand)
olmesartan (Benicar)
telmisartan (Micardis)
azilsartan (Edarbi)
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Angiotensin II Receptor Blockers:
Mechanism of Action


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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Angiotensin II Receptor Blockers:
Indications



Hypertension
Adjunctive drugs for the treatment of HF
May be used alone or with other drugs such as
diuretics
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Angiotensin II Receptor Blockers:
Adverse Effects
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Upper respiratory infections
Headache
May cause occasional dizziness, inability to
sleep, diarrhea, dyspnea, heartburn, nasal
congestion, back pain, fatigue
Hyperkalemia much less likely to occur
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Classroom Response Question
Which statement about angiotensin II receptor
blockers does the nurse identify as being true?
A. Hyperkalemia is more likely to occur than when
using ACE inhibitors.
B. Cough is more likely to occur than when using
ACE inhibitors.
C. Upper respiratory infection is a common
adverse effect.
D. Overdose is usually manifested by
hypertension and bradycardia.
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Calcium Channel Blockers:
Mechanism of Action


Cause smooth muscle relaxation by blocking the
binding of calcium to its receptors, preventing
muscle contraction
Results in:



Decreased peripheral smooth muscle tone
Decreased systemic vascular resistance
Decreased blood pressure
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Calcium Channel Blockers:
Indications
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Angina
Hypertension
Dysrhythmias
Migraine headaches
Raynaud’s disease
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Diuretics
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
Decrease 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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Diuretics (cont’d)


Thiazide diuretics are the most commonly used
diuretics for hypertension
Listed as first-line antihypertensives in the JNC7 guidelines
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Vasodilators
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
diazoxide (Hyperstat)
hydralazine HCl (Apresoline)
minoxidil (Loniten)
sodium nitroprusside (Nipride, Nitropress)
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Vasodilators:
Mechanism of Action


Directly relax arteriolar and/or venous smooth
muscle
Results in:

Decreased systemic vascular response
 Decreased afterload
 Peripheral vasodilation
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Vasodilators: Indications



Treatment of hypertension
May be used in combination with other drugs
Sodium nitroprusside and intravenous diazoxide
are reserved for the management of
hypertensive emergencies
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Nursing Implications
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
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Before beginning therapy, obtain a thorough
health history and head-to-toe physical
examination
Assess for contraindications to specific
antihypertensive drugs
Assess for conditions that require cautious use
of these drugs
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Nursing Implications (cont’d)
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

Educate patients about the importance of not
missing a dose and taking the medications
exactly as prescribed
Instruct patients to check with their physician for
instructions on what to do if a dose is missed;
patients should never double up on doses if a
dose is missed
Monitor BP during therapy; instruct patients to
keep a journal of regular BP checks
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Nursing Implications (cont’d)
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
Instruct patients that these drugs should not be
stopped abruptly because this may cause a
rebound hypertensive crisis, and perhaps lead to
stroke
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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Nursing Implications (cont’d)
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

Remind patients that medication is only part of
therapy. Encourage patients to watch their diet,
stress level, weight, and alcohol intake
Instruct patients to avoid smoking and eating
foods high in sodium
Encourage supervised exercise
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Nursing Implications (cont’d)
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
Teach patients to change positions slowly to
avoid syncope from postural hypotension
Instruct patients to 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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Nursing Implications (cont’d)
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
Male patients who take these drugs may not be
aware that impotence is an expected effect, and
this may influence compliance with drug therapy
If patients are experiencing serious adverse
effects, or if they believe the dose or medication
needs to be changed, they should contact their
physician immediately
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Nursing Implications (cont’d)


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 over-the-counter drugs, without first
getting the approval of their physician
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Nursing Implications (cont’d)

Educate patients about lifestyle changes that
may be needed

Weight loss
 Stress management
 Supervised exercise
 Dietary measures
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Nursing Implications (cont’d)


Monitor for adverse effects (dizziness,
orthostatic hypotension, fatigue) and for toxic
effects
Monitor for therapeutic effects
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