Chapter 12
The Cardiovascular
System and Drug Therapy
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2
Chapter 12
Topics
•
•
•
•
•
•
•
Anatomy and Physiology of the Cardiovascular System
Hypertension
Cardiac Arrhythmias
Angina and Heart Attack
Heart Failure
Hyperlipidemia
Herbal and Alternative Therapies
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Anatomy and Physiology of the Cardiovascular System
Cardiovascular Disease
• Is the leading cause of death in U.S.
• Includes heart attacks, hypertension (high blood pressure),
arrhythmia, angina, and heart failure
The Cardiovascular System
• Circulates blood and includes the heart and blood vessels
 Arteries
Bring needed oxygen and nutrients to tissues
 Veins
Carries carbon dioxide and toxic by-products to
heart from the tissues
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Anatomy and Physiology of the Cardiovascular System
The Cardiovascular System (continued)
• Capillaries
 Are tiny blood vessels
 Exchanges fluids, gases, and nutrients between the
blood and body tissues
• The heart pumps blood through the lungs where blood
receives oxygen and releases carbon dioxide via exhaling
• Heart’s four chambers made of cardiac muscle fibers
 Right and left atria
Receive blood that is brought to the heart
 Right and left ventricles
Push blood out to the lungs or other body tissues
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Anatomy and Physiology of the Cardiovascular System
The Circulatory
System and
Blood Flow
• Oxygenated
blood is depicted
in red
• Blood returning
from the body
(needs oxygen) is
shown in blue
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Anatomy and Physiology of the Cardiovascular System
Anatomy of the
Heart
One-way valves
between the atria
and ventricles
prevent blood
from flowing
backwards
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Anatomy and Physiology of the Cardiovascular System
The Heartbeat
• Systole
 Is when the heart is contracting and pumping blood
• Diastole
 Is when heart muscle relaxes, allowing blood to
passively flows in and fill up the heart chambers
• Muscle contraction
 Coordinated by conduction fibers carrying electrical
signals
 Caused by waves of positive-to-negative charges
Positively charged potassium, sodium, and calcium
ions cross the cell membrane and create the waves
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Anatomy and Physiology of the Cardiovascular System
The Heartbeat (continued)
• The electrical conduction system in the heart causes it to
beat in a regular manner
• SA node (heart’s natural pacemaker)
 Is a bundle of conduction fibers in right atrium
 Is where the heartbeat starts
 Initiates heartbeat 70 to 80 times per minute
• After leaving the SA node the signal follows this path
 AV node
bundle of His
Purkinje fibers
apex
ventricular myocardium
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Anatomy and Physiology of the Cardiovascular System
The ECG or EKG
• Each section of
the ECG wave
corresponds to
action in a part of
the heart
• PR portion
corresponds to
atrial function
• QT interval refers
to ventricular
function
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Anatomy and Physiology of the Cardiovascular System
Heart Rate (HR)
• Is reported in BPM
• Is measured by taking a person’s pulse
 Places to feel a pulse are the carotid artery in the neck
or at the radial pulse on the thumb side of the wrist
• Electrical signal flowing through the heart
 Is measured with an ECG machine
This machine translates these signals into a wave
line
Cardiologists look at the waves for heart
dysfunction
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Anatomy and Physiology of the Cardiovascular System
Blood Pressure
• Is the force of blood that fills the circulatory system
• Is a function of four factors
 Capacitance—how much blood is held in the system
 PVR—how constricted or relaxed the blood vessels are
 CO—force and volume of blood coming from the heart
 Renin–angiotensin system—a feedback mechanism
regulated by the kidneys
Balances fluid volume and vessel constriction
• Constriction or dilation of blood vessels will raise or lower
blood pressure, respectively
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Anatomy and Physiology of the Cardiovascular System
Blood Pressure (continued)
• Is regulated by the autonomic nervous system
• High blood pressure
 Is often caused by elevated PVR
 Can cause cardiovascular disease from stress on heart
 Affects vital organs and cause kidney failure or stroke
 Can be caused by an alteration
• Low blood pressure
 Can be caused by loss of blood
 Can cause shock
A condition in which vital organs begin to die due
to lack of blood flow
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Anatomy and Physiology of the Cardiovascular System
Maintaining
Blood Pressure
Blood and fluid
volume, one of
four factors that
control blood
pressure, is
maintained by the
kidneys and reninangiotensin
system
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Anatomy and Physiology of the Cardiovascular System
Measuring Blood Pressure
• Use a sphygmomanometer and a cuff wrapped around a
patient’s arm to measure blood pressure
 Cuff is inflated to apply pressure
Cuts off blood flow through the brachial artery in
arm
 Air is slowly released from the cuff, lowering the
pressure so blood begins flowing (with turbulence)
again
Turbulent blood flow is audible through a
stethoscope placed over the brachial artery
• Ideal blood pressure is 120/80 mm Hg or lower
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Anatomy and Physiology of the Cardiovascular System
Taking a Blood Pressure Reading
Systolic Blood
Pressure (SBP)
• Taken when blood starts flowing (with
turbulence) through the cuff again
• This is the first or upper number
reported in a blood pressure reading
Diastolic Blood
Pressure (DBP)
• Taken when blood freely flows without
turbulence
• This is the second or lower number
reported in a blood pressure reading
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Hypertension
Hypertension (High Blood Pressure)
• Affects more than 50 million people in the U.S.
• Is the elevation in systolic or diastolic blood pressure or
both
• Effects not immediately felt but can damage vital organs
(heart, kidneys, eyes, and brain) over time
• Contributing factors include smoking, diabetes, kidney
disease, age, family history, and gender
• Is a progressive condition that may require step therapy
and multiple medications
 Do not stop using blood pressure medications abruptly
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Hypertension
Blood Pressure Category
Normal
Prehypertension
(if have risk factors for heart
disease, hypertension begins
at ≥ 130/85)
Hypertension
Stage 1
Stage 2
Hypertensive Emergency
SBP (mm
Hg)
< 120
120–139
and/
or
and
or
DBP (mm
Hg)
< 80
80–89
≥140 or
40–159
or
or
≥90
90–99
≥ 160
≥ 180
or
or
≥ 100
≥ 110
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Hypertension
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Hypertension
ACE Inhibitors
• Indications: hypertension, angina, heart attack, heart
failure, and kidney disease
• Indications (other): protect kidneys from long-term
damage if diabetic
• Mechanism of Action: regulate blood pressure through the
renin–angiotensin system; allows blood vessels to relax
• Routes: all are oral; enalapril (Vasotec, Enalaprilat) also IV
• Side Effects (common): headache, dizziness, fatigue, mild
diarrhea, and dry hacking cough
• Side Effects (rare): angioedema (allergic-like reaction)
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Hypertension
ACE Inhibitors (continued)
• Cautions
 Hypotension (low blood pressure)
 Elevated potassium levels (hyperkalemia)
 Do not take if pregnant
 Do not take if have bilateral renal artery stenosis
ArBs
• Indications: hypertension, heart failure; used as alternative
if patient cannot tolerate ACE inhibitors
• Indications (other): renal protective effects for diabetes
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Hypertension
ArBs (continued)
• Mechanism of Action: blocks the receptors to which
angiotensin II (a potent vasoconstrictor) binds preventing
constriction and causing blood vessels to relax, which
lowers blood pressure
• Routes: all are oral
• Side Effects (common): headache, dizziness, fatigue, and
mild diarrhea
• Side Effects (other): more respiratory tract infections; may
experience hypotension if taking diuretics; and special
dosing and monitoring may be required if kidney or liver
impairment is evident
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Hypertension
Calcium-Channel Blockers
• Indications: hypertension, heart failure, and arrhythmias
 Are usually not the first therapy choice for
hypertension due to adverse effects
 May be used if patient has more than one
cardiovascular condition
• Mechanism of Action: prevent calcium from entering into
smooth muscle cells in arterial walls
 These muscle cells relax to open blood vessels which
lowers blood pressure
• Routes: all are oral; some are also IV
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Hypertension
Calcium-Channel Blockers (continued)
• Side Effects (common): headache, dizziness, fatigue,
constipation, nausea, heartburn, and flushing
• Cautions: Can cause fluid retention (edema) and heart
palpitations
• Some are in extended-release dosage forms
 Do not crush or chew or could drastically lower blood
pressure because the entire large dose would release
 May release the drug from a capsule or tablet (ghost
tablet) that appears in stool; warn patients
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Hypertension
Diuretics
• Indication: cornerstone of hypertension treatment
 Are the first or second choice to get blood pressure
under control
• Mechanism of Action: help the kidneys eliminate sodium
and fluid from the body
 Decreases blood volume, lowering blood pressure
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Hypertension
Alpha and Beta Blockers
• Indication: hypertension
 Beta blockers have beneficial effects on the heart,
especially after a heart attack
• Indication (alpha): men with both high blood pressure and
benign prostatic hyperplasia
• Mechanism of Action (alpha and beta): adrenergic
inhibitors that block certain adrenaline receptor types
• Are inexpensive and available generically
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Your Turn
Question 1: What is the function of the SA node?
Answer: The SA node, called the heart’s natural pacemaker,
sends out an electrical signal to start the contracting
(heartbeat) of the heart muscle.
Question 2: A patient has been diagnosed with hypertension.
What first-line drug therapy is likely to be prescribed?
Answer: Drug therapy for hypertension usually begins with a
beta blocker or a diuretic.
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Cardiac Arrhythmias
About Cardiac Arrhythmias
• Is any deviation from sinus rhythm
 Sinus rhythm is the normal heart rhythm
 Deviations includes changes in heart beats or electrical
conductivity
• Tachycardia refers to increased heart rate and bradycardia
is decreased heart rate
• Flutter
 Occurs when select portions (the atria, for example)
are slightly out of sync with the rest of the heart
 Is not necessarily life threatening
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Cardiac Arrhythmias
About Cardiac Arrhythmias (continued)
• Fibrillation
 Occurs when large portions of the heart beat out of
sequence
 Can be life threatening
 Ventricular fibrillation
No blood flows through the heart
Electronic defibrillation shocks heart into sequence
• Are monitored by and diagnosed by ECG readings
• Symptoms are palpitations, syncope (fainting), weakness,
lightheadedness, sweating, chest pain, and skin pallor
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Cardiac Arrhythmias
Drugs for Cardiac Arrhythmias
• Restore normal sinus rhythm by changing the heart rate
and conductivity
• Are categorized into classes by their mechanisms of action
 Categories include other drug classes that have effects
on heart rhythm
• Are chosen and dosed individually, based on desired
patient results
• Drug interactions can alter the effectiveness of these drugs
(see Table 12.5)
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Cardiac Arrhythmias
Class I (Membrane-Stabilizing Agents)
• Indication: arrhythmias
• Mechanism of Action: block sodium channels in cardiac
muscle cells
 Slows the influx of sodium and the cell membrane
becomes more stable and less able to depolarize
 Thus, the electrical charge must be stronger to
stimulate cardiac cells to contract and make the heart
beat
 The effect regulates heart rhythm because it decreases
the incidence of abnormal beats
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Cardiac Arrhythmias
Class II (Beta Blockers)
• Indication: arrhythmias
• Mechanism of Action: block beta-one receptors and inhibit
sympathetic nervous system activity on the heart
 Slows conduction in the AV node and slows heart rate
Class III (Potassium-Channel Blockers)
• Indication: arrhythmias
• Mechanism of Action: block potassium channels in cardiac
muscle cells which slows the influx of potassium
 Cell membrane is more stable; less able to depolarize
 Regulates heart rhythm by decreasing abnormal beats
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Cardiac Arrhythmias
Class IV (Calcium-Channel Blockers)
• Indication (diltiazem and verapamil): atrial fibrillation, a
common, nonfatal heart arrhythmia
• Mechanism of Action: block calcium from entering cardiac
muscle cells
 Dilates cardiac arteries, providing better oxygen supply
 Heart rate slows and the heart works more efficiently
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Cardiac Arrhythmias
Digoxin
• Indications: atrial fibrillation and flutter
• Mechanism of Action: blocks sodium-potassium ATPase
(enzyme regulating influx of these ions in cardiac cells)
 Alters SA node conductivity, conduction velocity
through the heart, and rest time between beats
 Increases the force and velocity of muscle contraction,
making the heart pump more efficiently
• Has as a narrow therapeutic window
 Monitor effects and possibly adjust doses
• Cautions: see Table 12.6 for drug interactions
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Cardiac Arrhythmias
Digoxin Side Effects
• Do not change between brand and generic drugs
 Strength differences can affect blood concentrations
• Toxicity can occur
 Symptoms include visual disturbances (seeing yellow or
green halos around objects), headache, dizziness,
confusion, nausea, and vomiting
 Seek medication attention immediately
• Severe: gynecomastia (breast enlargement), anorexia,
mental disturbances (anxiety, depression, delirium,
hallucination), heart block (very slow heartbeat)
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Angina and Heart Attack
About Angina Pectoris (Angina)
• Is chest pain caused by inadequate blood flow to a portion
of the heart (i.e., myocardial ischemia)
 Ischemia usually occurs due to a blockage in the
coronary arteries that supply the heart itself with blood
• Is not extensive enough to be a heart attack
• Causes recurring chest pain episodes
• Heart attack
 Is one or more coronary artery becoming 70% or more
blocked and tissue damage in that heart area occurs
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Angina and Heart Attack
Coronary Arteries
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Angina and Heart Attack
Types of Angina
Stable
Angina
• Predictable pattern of chest pain and
tightness; happens to specific triggers,
such as exercise, physical pain, and stress
Unstable
Angina
• Chest pain and tightness that occurs with
increasing frequency and less predictability
• Possible warning of impending heart attack
Variant
Angina
• Chest pain that involves spasm of the
coronary blood vessels
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Angina and Heart Attack
Heart Attack (MI)
• Is muscle cell death (infarct) due to the deprived of oxygen
• Procedures for extensive coronary artery blockage
 Cardiac catheterization
Is a procedure to reopen blocked arteries
 Coronary bypass surgery
A vessel from the leg is used to create an arterial
bypass around the blockage, restoring blood flow
Stent (supportive structures made of metal wire
mesh) also placed surgically to keep coronary
arteries open
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Angina and Heart Attack
Symptoms of a Heart Attack
• Tightness, heaviness, or squeezing in chest
• Chest, neck, or jaw pain
• Chest pain that radiates down the left arm
• Indigestion or nausea
• A sense of impending doom
• Weakness or fatigue
• Sweating
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Angina and Heart Attack
Drugs for Angina and Heart Attack
• Angina
 Treatment is twofold: providing immediate relief of
chest pain and preventing it entirely
 Goal of drug therapy
Dilate blood vessels to reduce the demand for and
increase the delivery of oxygen to myocardial tissue
Prevent ischemia from approaching the level of
infarction
• Heart attack is an emergency
 Technicians do not dispense many of the drugs
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Angina and Heart Attack
Drugs for Angina and Heart Attack (continued)
• Technicians in an inpatient setting may stock emergency
room drug kits and crash carts for the floors
 Check drug expiration dates to ensure that all agents
will work when needed
• Many drugs are injectable vasopressors (see Table 12.7)
 Produce vasoconstriction and a rise in blood pressure
 Restore cardiovascular system function during and after
cardiac arrest and shock situations
• Technicians should refer to institution’s protocol for
specific medications kept in emergency drug kits
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Angina and Heart Attack
Vasodilators
• Indication: angina
• Mechanism of Action: dilating the coronary arteries
 Allows greater oxygen and nutrient supply to reach
cardiac muscle tissue, which relieves chest pain
• Most frequently used vasodilators are nitrates
• Dosage Forms (nitrates): immediate-release products for
angina attack; long-acting to prevent angina attacks
• Dosage Forms (nitroglycerin): short-acting to produce
rapid absorption after one dose
 Sublingual tablets and sprays most common
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Angina and Heart Attack
Vasodilators: Nitrates
• Patients should keep their nitroglycerin with them at all
times and use it when they experience chest pain
• Long-acting forms are used on a scheduled daily basis to
prevent angina attacks from occurring
 Take once a day and allow an 8-hour span being drugfree to decrease risk of tolerance
• Side Effects (common): headache, dizziness, blurred vision,
flushing, increased heart rate, hypotension, and agitation
 Some side effects can intensify if taken with alcohol,
hypertension drugs, or other vasodilation drugs
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Angina and Heart Attack
Vasodilators: Nitrates and Cautions
• Do not take with erectile dysfunction drugs
• Do not swallow sublingual and buccal tablets; place in the
mouth and allow to dissolve
• Swallow long-acting oral forms on an empty stomach with
a full glass of water
• If do not get relief within 15 minutes of taking a shortacting nitroglycerin, repeat one dose and call 911
• Keep sublingual nitroglycerin tablets in original ambercolored container; protect from light, heat, and moisture
 Once bottle is opened, only good for six months
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Your Turn
Question 1: What is the difference between flutter and
fibrillation?
Answer: Flutter occurs when select portions of the heart are
slightly out of sync with the rest of the heart; it is usually not
life threatening. Fibrillation occurs when large portions of the
heart beat out of sequence; it can be life threatening.
Question 2 Nitrates are available in short-acting and long-acting
dosage forms. What is the function of each dosage form?
Answer: Short-acting (nitroglycerin) is used to abort an
angina attack. Long-acting dosage forms are used to prevent
angina attacks.
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Angina and Heart Attack
Other Drugs for Angina
• ACE inhibitors, calcium-channel blockers, and beta blockers
 Indications: angina and heart attack
 Sometime used during the acute heart attack itself
 Are usually used after a heart attack has occurred
 Have beneficial effects on heart tissue that has already
experienced ischemia
Increase oxygen supply to cardiac tissue and
increase pumping efficiency
Reduce stress on a heart that suffered an infarction
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Heart Failure
About Heart Failure
• Is a condition where the heart does not pump sufficiently
• Is characterized by weakness, fatigue, severe fluid
retention, and difficulty breathing due to pulmonary
edema (fluid in the lungs)
• Causes vital organs to shut down due to lack of blood
 Half of patients with heart failure die within 5 years
• Hypertension and coronary artery disease are the primary
causes
 Other causes are alcoholism, liver disease, kidney
disease, vavular heart disease, anemia, and drug
therapy
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Heart Failure
Drugs for Heart Failure
• Drugs used for hypertension, angina, and arrhythmias can
be used for heart failure
 The difference between using the drugs for heart
failure and other cardiovascular conditions is the dosing
amounts and frequencies
• Loop diuretics are used for heart failure to eliminate extra
body fluid so the heart does not have to work as hard
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Hyperlipidemia
About Hyperlipidemia
• Is a condition of elevated cholesterol, phospholipids,
and/or triglycerides in the blood
• Leads to cardiovascular disease and coronary artery
blockage
• Many people with hyperlipidemia also make too much
cholesterol in their livers
• Cholesterol
 Made in the body and ingested with food
 Eating high-fat foods can raise cholesterol levels
 Accumulation leads to blockage of and dysfunction in
blood vessel walls
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Hyperlipidemia
About Hyperlipidemia (continued)
• Cholesterol (continued)
 Is packaged into lipoproteins and triglycerides
 LDL are worst type and contribute to artery blockages
 HDL are good and break up plaques and blockages in
vessels
 Triglycerides (lipid molecule) contribute to
atherosclerosis (hardening of arteries due to fat)
Abnormal Blood Lipid Levels
Total cholesterol > 200 mg/dL
LDL > 160 mg/dL
HDL < 45 mg/dL
Triglycerides > 150 mg/dL
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Hyperlipidemia
Drugs for Hyperlipidemia
• Indications: prevent a first heart attack (primary
prevention) or prevent subsequent attacks after an MI
(secondary prevention)
• Many pharmacies screen for high cholesterol or monitor
drug therapy for hyperlipidemia
 Technicians may help with ordering supplies and
operating the machine that runs these tests
Statins
• Lower LDL cholesterol (primarily) and can have beneficial
effects on other lipids see Table 12.9
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Hyperlipidemia
Statins (continued)
• Indication: first-line therapy for hyperlipidema
• Mechanism of Action: reduce the amount of cholesterol
made in the body
 Block an enzyme, HMG-CoA reductase, which is
required for cholesterol production
• Routes: all are oral
• Side Effects (common): upset stomach, diarrhea, and
muscle aches and weakness
• Side Effects (severe, rare): muscle breakdown
(rhabdomyolysis) may cause permanent kidney failure;
liver toxicity
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Hyperlipidemia
Statins (continued)
• Cautions
 Work best when taken at night
 Do not take during pregnancy, or if planning to get
pregnant
 Do not take with grapefruit juice
 Several drugs interact with statins
Technicians heed all computer alerts when filling a
statin drug prescription
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Hyperlipidemia
Fibrates
• Indication: lower high cholesterol (especially elevated
triglycerides); alternative to statins
• Side Effects: upset stomach, diarrhea, indigestion, and
abdominal cramps
• Cautions: Probably should not take if have gallbladder
problems; do not take in combination with statins
Ezetimibe
• Indication: inhibits cholesterol absorption from GI tract;
may not significantly reduce large levels of cholesterol
• Side Effects: abdominal cramps and diarrhea
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Hyperlipidemia
Niacin Vitamin B3 (Nicotinic Acid)
• Is an oral dietary supplement available over the counter as
well as via prescription
• Indications: reduces triglycerides and LDL cholesterol while
raising HDL cholesterol
• Side Effect: vasodilation in the face and neck, which causes
flushing (reddening) and itching
 Can reduce by taking aspirin 30 minutes before dose
 Take before bedtime, so it occurs during sleep
 Prescription dosage forms formulated to release the
drug slow to reduce this side effect
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Herbal and Alternative Therapies
• Omega 3 fatty acids
 Used for high cholesterol, hypertension, coronary artery
disease, high triglycerides, and hypertriglyceridemia
• Plant sterol esters
 Can significantly lower LDL cholesterol and also helps
with hyperlipidemia
• Alpha tocopherol (vitamin E)
 Used for cardiovacular disease, cancer, and diabetic
neuropathy
• Garlic
 Has antihyperlipidemic, antihypertensive and
antifungal effects
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Summary
• ACE inhibitors, beta blockers, and calcium-channel
blockers are used in almost all cardiovascular conditions
• ARBs are used for hypertension, nitrates for angina, and
antihyperlipidemic agents (statins and fibrates)
• Drugs used for heart arrhythmias are divided into four
classes, all of which have complications; some have
serious side effects and toxicities
• Beta blockers and calcium-channel blockers are also used
for arrhythmia
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