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

Lilley
Pharmacology
Antihypertensive Drugs
Blood Pressure Review
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Blood pressure = CO × SVR
•
CO = cardiac output
•
SVR = systemic vascular resistance
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Stages of Blood Pressure
1. Normal <120 over </ 80
2. Prehypertension 120 or >/ 80 or >
3. Hypertension 140/90
4. Stage 1- 140-159/90-99
5. Stage 2- 160 or >/100or >
6. Malignant Hypertension or Hypertensive
Crisis- sustained 200 or >/110 or >
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Classification of BP
• Hypertension
• Unknown
can also be defined by its cause
Cause
 Essential, or Primary Hypertension
 90-95% of cases
•
Known cause
 Secondary hypertension
 Approximately 10% of cases
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Antihypertensive Drugs
• Medications
used to treat hypertension
• Categories
 Adrenergic drugs
 Angiotensin-converting enzyme (ACE) inhibitors
 Angiotensin II receptor blockers (ARBs)
 Calcium channel blockers (CCBs)
 Beta blockers
 Diuretics
 Vasodilators
 Direct renin inhibitors
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Adrenergic Drugs Actions
Centrally acting alpha2 receptor agonists
 Stimulate alpha2-adrenergic receptors in the brain
 Decrease sympathetic outflow from the CNS
 Stimulate alpha2-adrenergic receptors, thus reducing renin activity in the
kidneys
 Alpha blockers relax certain muscles and help small blood vessels remain
open
 They work by keeping the hormone norepinephrine from tightening the
muscles in the walls of smaller arteries and veins
 Blocking that effect causes the vessels to remain open and relaxed. This
improves blood flow and lowers blood pressure
 Results in decreased blood pressure
 Example: doxazosin (Cardura)
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Adrenergic Drugs
• Peripheral
alpha1 blockers/antagonists
 Block alpha1-adrenergic receptors
 doxazosin (Cardura)
 terazosin (Hytrin)
 prazosin (Minipress)
 First dose phenomena, tachycardia, dyspnea, feeling
faint
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Adrenergic Drugs
• Beta
blockers
 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), metoprolol (Lopressor)
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Alpha Adrenergic
&
Beta-Adrenergic Drugs
Dual-action alpha1 and beta receptor blockers
 Reduce BP & heart rate (beta1 receptor blockade)
 Cause vasodilation (alpha1 receptor blockade)
 Examples: carvedilol (Coreg) and labetalol (Normadyne, Trandate)
 Result in decreased blood pressure & HR
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Classification
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There are two predominant types of beta-adrenergic receptors: beta-1 and beta-2.
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Beta-1 receptors are found primarily in the heart, while beta-2 receptors are found
primarily in tissues other than the heart, such as the airway, muscle and blood
vessels.
•
Drugs that mostly target beta-1 receptors are called cardioselective beta blockers.
Non-cardioselective beta blockers bind to both receptor types.
•
Examples of cardioselective beta blockers commonly used in the United States are
metoprolol and atenolol. Examples of the non-cardioselective type are propranolol and
nadolol.
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Beta Blockers Continued
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Beta-blockers are used for their antagonistic effect on
cardiac beta-1 adrenoceptors
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Two types of beta-blockers are available: beta-1 selective
adrenoceptor antagonists (metoprolol, atenolol)
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And nonselective beta-1/ beta-2 adrenoceptor antagonists
cardiac & pulmonary effect (carvedilol, propranolol, sotalol,
timolol).
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Beta-2 receptor antagonism is associated with
bronchoconstriction.
•
Many commercially available beta-1 selective blockers have
high affinity for beta-2 receptors
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So, both selective and nonselective beta-blockers may cause
bronchoconstriction, which can lead some patients to
experience a cough reflex.
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Adrenergic Drugs: Indications
• All
used to treat hypertension
• Centrally
acting alpha2 receptor agonists
 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 (reduces anxiety
and restlessness)
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Adrenergic Drugs: Indications (cont’d)
• Peripherally
acting alpha1 receptor agonists
 Treatment of hypertension
 Some used to relieve symptoms of benign prostatic
hyperplasia (BPH)- vasodilating effect
 Management of severe heart failure (HF) when used
with cardiac glycosides and diuretics
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Adrenergic Drugs:
Adverse Effects
• 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
•
Other
 Headaches
 Sleep disturbances
 Nausea
 Rash
 Cardiac disturbances (palpitations)
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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
• 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 Examples
• captopril
(Capoten)
• benazepril
(Lotensin)
• enalapril
(Vasotec)
• fosinopril
(Monopril)
• lisinopril
(Prinivil)
• moexipril
(Univasc)
• quinapril
(Accupril)
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ACE Inhibitors:
Mechanism of Action
• 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
• 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
• Hypertension
• HF
(either alone or in combination with
diuretics or other drugs)
• Slow
progression of left ventricular
hypertrophy after MI (cardio protective)
• 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 angiotensinconverting 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 cardio-protective 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)
• Drugs
of choice in hypertensive patients with
• Drugs
of choice for diabetic patients
HF
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ACE Inhibitors
• Captopril
and lisinopril are NOT prodrugs
• 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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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: Adverse Effects
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Fatigue
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Dizziness
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Headache
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Mood changes
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Impaired taste
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Dry, nonproductive cough, which reverses when
therapy is stopped
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Angioedema: rare but potentially fatal
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Potential hyperkalemia
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First dose hypotension may occur
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Angiotensin II Receptor Blockers
• Also
referred to as angiotensin II blockers or
ARBs
• Well
tolerated
• Rarely
cause a dry cough
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Angiotensin II Receptor Blockers
• losartan
(Cozaar)
• valsartan
(Diovan)
• irbesartan
(Avapro)
• candesartan
(Atacand)
• olmesartan
(Benicar)
• telmisartan
(Micardis)
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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 – results in vasodilation
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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
• 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
• Angina
• Hypertension
• Dysrhythmias
• Migraine
headaches
• Raynaud’s
disease
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Diuretics
• Decrease
volumes
plasma and extracellular fluid
• Results
 Decreased preload
 Decreased cardiac output
 Decreased total peripheral resistance
• Overall
effect
 Decreased workload of the heart and decreased blood
pressure (from decreased volume)
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Diuretics
• Thiazide
diuretics are the most commonly used
diuretics for hypertension
• Listed
as first-line antihypertensives
guidelines
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Vasodilators
• diazoxide
(Hyperstat)
• hydralazine
HCl (Apresoline)
• sodium
nitroprusside used in ICU (Nipride,
Nitropress)
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Vasodilators:
Mechanism of Action
• Directly
muscle
• Results
relax arteriolar and/or venous smooth
in:
 Decreased systemic vascular response
 Decreased afterload
 Peripheral vasodilation
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Vasodilators: Indications
• Treatment
• May
of hypertension
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
• 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
• 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 BP checks
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Nursing Implications
• Instruct
patients that these drugs should not
be stopped abruptly because this may cause a
rebound hypertensive crisis, and perhaps lead
to stroke
• Administer
IV forms with extreme caution, and
use an IV pump
• Oral
forms should be given with meals or per
label, so that absorption is more gradual
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Nursing Implications
• 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
• 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
• Report
weight gain or loss, chest pain,
palpitations, or excessive fatigue (HF
symptoms)
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Nursing Implications
• 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
• Hot
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 over-the-counter
drugs, without first getting the approval of
their physician, and discuss all other
medications they are taking
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Nursing Implications
Educate patients about lifestyle changes that may be
needed
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Weight loss
Stress management
Supervised exercise
Dietary measures
Nurses: Monitor for adverse effects including
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dizziness, orthostatic hypotension
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Monitor for therapeutic effects- which would be?
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Digoxin!
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Digoxin belongs to a class of medications called cardiac
glycosides
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Digoxin works by affecting certain minerals (sodium
and potassium inside heart cells. This reduces strain on
the heart and helps it maintain a normal, steady, and
strong heartbeat
•
Treating an irregular heartbeat (atrial fibrillation) can
decrease the risk for blood clots an effect that may
reduce risk for a heart attack or stroke.
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More Digoxin!
•
Acute digitalis toxicity can result from unintentional, suicidal,
or homicidal overdose of the digitalis preparation digoxin, or
accidental ingestion of plants that contain cardiac glycosides
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Chronic toxicity in patients on digoxin therapy may result from
deteriorating renal function, dehydration, electrolyte
disturbances, or drug interactions
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Alterations in cardiac rate and rhythm from digitalis toxicity
may simulate almost every known type of dysrhythmia
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Digitalis toxicity produces CNS, visual, GI, and cardiac
manifestations. Nausea, vomiting, and drowsiness are among
the most common extra-cardiac manifestations.
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Visual aberration often is an early indication of digitalis
toxicity. Yellow-green distortion is most common
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Yellow halos around lights (xanthopsia)
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Van Gogh Self-Portrait
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Van Gogh’s Starry Night
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