Chapter 13
The Blood and Drug Therapy
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Chapter 13
Topics
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Anatomy and Physiology of the Blood
Anemia
Stroke
Clotting Disorders
Herbal and Alternative Therapies
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Anatomy and Physiology of the Blood
Blood Functions
• General
 Supplies the cells of the body with oxygen and
nutrients
 Carries hormones and enzymes to control body
functions
 Helps to regulate body temperature
• Specific to pharmacokinetics
 Absorbs drug and carries drug molecules as either
dissolved substances or bound to proteins (albumin)
 Distributes drug to organs and tissues
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Anatomy and Physiology of the Blood
Blood Composition
• Cells or formed elements (45%)
 Erythrocytes, leukocytes, platelets
• Plasma (55%)
 Water, proteins, and other substances
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Anatomy and Physiology of the Blood
Blood Composition (continued)
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Anatomy and Physiology of the Blood
Blood Cells
• Three types of cells
 RBCS or erythrocytes
 Are produced in bone marrow (erythropoiesis)
 Are formed by iron, folate, and vitamin B12
 Contain iron and hemoglobin to which oxygen and
carbon dioxide bind during transport
 WBCs or leukocytes
 Fight disease (central to the immune system)
 Platelets or thrombocytes
 Help the blood clot during injury
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Anatomy and Physiology of the Blood
Platelets and
Blood Clot
Formation
• Tissue damage
triggers
platelets to
accumulate and
activates
clotting factors
to start
coagulation
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Anatomy and Physiology of the Blood
Coagulation Cascade
• Process
 Involves a series of reactions that attract thrombin and
fibrin (coagulation proteins)
 Results in a functional blood clot
• Components
 Includes two pathways, extrinsic and intrinsic, that
converge with the use of clotting factor X, thrombin,
and fibrin to form a common pathway
 Malfunctions or abnormalities in pathways result in
coagulation problems
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Anatomy and Physiology of the Blood
Coagulation Cascade (continued)
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Anatomy and Physiology of the Blood
Effects of Clotting Disorders
• Blood Loss
 May be life-threatening and require transfusion
• Blood Typing
 Allows the matching of donor blood to a recipient for
transfusion
 Is determined by specific antigen proteins on the
surface of RBCs
 Includes Types O, A, B, and AB
 Type O: universal donor
 Type AB: universal recipient
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Anemia
About Anemia
• Lack of normal, healthy RBCs containing
functional hemoglobin in the blood
• Symptoms: rapid heartbeat, lightheadedness, and
breathlessness
• Symptoms (chronic): fatigue, weakness, headache, vertigo,
faintness, sensitivity to cold, pallor, loss of skin tone
• Most Common Cause: inadequate production of RBCs
• Three Types of Anemia: hemolytic, iron-deficiency, and
pernicious
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Anemia
Anemia Types
Description
Hemolytic
Anemia
Iron-deficiency
Anemia
Rapid destruction of RBCs due to infection,
drug therapy; blood loss often requires
transfusion
Folate deficiency from inadequate nutrition;
common among alcoholics
Pernicious
Anemia
Deficiency in vitamin B12 that develops over
time; quick results with vitamin B12 therapy
Other
Caused by slowing of erythropoiesis from
chronic kidney disease or cancer
chemotherapy; therapy with erythropoietin
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Anemia
Drugs for Anemia
• Diagnosis based on laboratory markers Hgb and HCT
 Blood values measure Hgb and oxygen-carrying
capacity in the blood
 Anemia is suspected if values are low
• Therapy determined by type and cause
 For nutrient deficiency, replace nutrient
 For altered hematopoiesis, administer erythropoietin
• Multiple causes of anemia make treatment complicated
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Anemia
Iron and Other Supplements
• Iron, folate, and vitamin B12 are used as supplements for
anemia caused by nutrient deficiency (see Table 13.1)
• Indications (iron): iron-deficiency anemia; anemia from
CKD (in combination with hematopoietic agents)
• Indication (folic acid, low doses): prenatal
supplement for fetal brain and spinal development
• Indication (folic acid, high doses): anemia due to
alcoholism
• Indications (vitamin B12): pernicious anemia; prevent
neuropathy and certain types of dementia
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Anemia
Iron and Other Supplements (continued)
• Side Effects (iron, common): constipation, stomach upset,
urine discoloration, dark stools
• Side Effects (vitamin B12 , common): itching, diarrhea,
headache, anxiety
• Caution (oral iron): enteric coated; do not crush or chew
• Caution (oral iron): most oral iron supplements are OTC
 Poison risk to children; iron overdose can be fatal
• Caution: do not take with antacids, other acid-reducing
drugs, tetracycline, fluoroquinolones
• Caution (iron dextran): severe allergic reaction
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Anemia
Hematopoietic Agents: Erythropoietin and
Darbepoetin
• Indications: anemia associated with CKD
• Indications (other): cancer chemotherapy causing bone
marrow suppression which affects blood cell production
• Always use with iron supplements; these agents deplete
iron stores as RBC production increases
• Mechanism of Action: supplements the body’s normal
production of erythropoietin
 Stimulates blood cell production in the bone marrow
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Anemia
Hematopoietic Agents: Erythropoietin and
Darbepoetin (continued)
• Routes: IV, SC injection
• Side Effects (common): headache, fatigue, fever,
muscle/joint pain, swelling, diarrhea, nausea, vomiting
• Side Effects (other): high blood pressure, clotting, rapid
heartbeat
• Caution: monitor with CBC, Hgb, HCT lab tests; technician
may retrieve results; Hgb should be below 12 g/dL
• Storage and Handling: refrigerate, do not shake
or dilute; protect darbepoetin from light
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Your Turn
Question 1: Both RBCs and platelets are components of blood.
How are their functions different?
Answer: RBCs carry oxygen and carbon dioxide to and from
body cells. Platelets help the blood clot during injury by
clumping together and sticking to surrounding tissue.
Question 2 What is the purpose of taking iron supplements with
erythropoietin?
Answer: Hematopoietic agents such as erythropoietin
deplete iron stores as RBC production increases.
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Stroke
About Stroke
• An interruption in oxygen supply to the brain (the brain
requires constant supply of oxygenated blood)
• Without oxygen, takes minutes to lose consciousness and
for tissue damage to occur
 The brain cannot regenerate; cell death is permanent
• Two types of stroke: ischemic and hemorrhagic
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Stroke
Ischemic Stroke
• Results from an obstruction of blood flow to the brain by a
blood clot or cholesterol plaque
• Brief and temporary blockage known as a TIA
 Often a precursor (forewarning) of stroke
• Risk Factors: high cholesterol, cardiac arrhythmia, coronary
artery disease, prosthetic heart valve, diabetes,
hypercoagulable states, obesity, and physical inactivity
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Stroke
Hemorrhagic Stroke
• Results from a rupture in a blood vessel that supplies an
area of the brain
 Blood vessels in brain are weakened by certain
conditions and form aneurysms that easily burst
• Risk Factors: high blood pressure, cigarette smoking, and
excessive alcohol intake
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Stroke
Treatment of Stroke
• Most drug therapy for stroke is aimed at prevention rather
than treatment after the fact
 Risk of stroke is difficult to predict
• Many times, anticoagulation therapy starts only after
someone has had a stroke or a TIA
• Low-dose aspirin therapy is used for
patients who have multiple risk factors
with no history of stroke
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Clotting Disorders
About Clotting Disorders
• Involves both hypercoagulation (overproduction of blood
clots) and hemophilia (inability to produce blood clots)
• Commonly caused by genetics; may also be the result of
certain risk factors
• Two types of clots: DVT (forms in an extremity such as the
lower leg) and PE (forms in the lungs)
• Embolus (a piece of a clot) can dislodge and travel to the
heart, brain, or lungs; creates life-threatening emergency
• Treatment (DVT, PE): often lasts 3-6 months to prevent
emboli as the body dissolves the clot
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Clotting Disorders
Drugs for Stroke and Clotting Disorders
• Prevention and treatment of unwanted clots includes
anticoagulants, antiplatelet agents, thrombolytics
• Specific lab tests used to monitor patients during therapy
 PTT measures function of the intrinsic pathway of
coagulation cascade; monitors heparin therapy
 PT measures function of the extrinsic pathway of
coagulation cascade; monitors warfarin therapy
 INR gives a reference for the extrinsic pathway of
coagulation cascade; monitors warfarin therapy
• Technicians may gather lab results, administer fingerstick
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Clotting Disorders
Anticoagulant Agents
• Indication: halt growth of emboli and stop them from
forming as the body reabsorbs the clot on its own
• Treatment (early): usually starts with IV heparin to keep
the clot from growing
• Treatment (later): LMWH via self-injection; oral warfarin
therapy begins upon patient discharge from hospital
• Indication (warfarin): long-term anticoagulation; requires
5+ days for onset, so heparin or an LMWH co-administered
• Indication (heparin): immediate, short-term IV
anticoagulation treatment of blood clots
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Clotting Disorders
Anticoagulant Agents: Heparin
• Routes: continuous IV infusion, SC injection
• Indication: blood clots; only anticoagulant used during
pregnancy because it does not cross placental barrier
• Indications (other): flushes IV lines to keep them open; is
given SC for prevention of blood clots in high-risk patients
• Mechanism of Action: inhibits clotting factors and
inactivates thrombin and factor Xa in coagulation cascade
 Also affects the platelets’ ability to clump together
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Clotting Disorders
Anticoagulant Agents: LMWHs
• Mechanism of Action: inhibit clotting factors and inactivate
factor Xa in coagulation cascade
• Route: SC self-injection; given once or twice a day
• Indication: bridge therapy from IV heparin to oral warfarin
Anticoagulant Agents: Fondaparinux
• Mechanism of Action: inhibits factor Xa
• Route: SC self-injection; given once a day
Anticoagulant Agents: Direct Thrombin Inhibitors
• Inhibit thrombin directly; given as continuous infusions
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Clotting Disorders
Anticoagulant Agents: Warfarin
• Indications: heart valve disease, artificial heart valve
placement, prior stroke, atrial fibrillation, DVT, PE, MI,
other heart conditions
• Mechanism of Action: inhibits the production of vitamin
K–dependent clotting factors in the liver
• Routes: oral, IV
• Common Doses: individualized to each patient; frequent
lab testing is necessary
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Clotting Disorders
Anticoagulant Agents: Common Side Effects
• Heparin: bruising, bleeding, thrombocytopenia (low
platelet count)
• LMWHs: bruising, bleeding, fever, thrombocytopenia, pain
at injection site
• Fondaparinux : nausea, fever, anemia, bleeding,
thrombocytopenia
• Direct thrombin inhibitors: nausea, headache, back pain,
bleeding
• Warfarin: bleeding, hair loss, skin lesions, purple/blue toe
syndrome
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Clotting Disorders
Anticoagulant Agents: Cautions
• Heparin: do not inject IM
• LMWHs, fondaparinux, and direct thrombin inhibitors: do
not use in some cases of severe kidney problems
• Warfarin: many drug interactions (do not take with aspirin
or NSAIDs); be consistent with intake of dietary vitamin K
and the time of day when daily doses are taken
• All anticoagulants: considered high-risk medications;
require close monitoring of patient and lab values
to avoid life-threatening underdosing or overdosing errors
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Clotting Disorders
Anticoagulation Antagonists
• Indication (vitamin K): reverses warfarin effects when signs
of bleeding are present
• Indication (protamine): reverses heparin effects when
hemorrhage or high risk of hemorrhage is present
• Side Effects (vitamin K, common): flushing, changes in
taste, dizziness, sweating, rapid pulse, difficulty breathing
• Cautions (vitamin K): use SC whenever possible; give IM or
IV very slowly (rapid administration can be fatal)
 Mix in preservative-free normal saline or dextrose 5%
in water (D5W)
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Clotting Disorders
Antiplatelet Agents
• Indication: decrease the risk of stroke, DVT, and clotting
associated with cardiovascular blockage
 Usually given after a stroke, DVT, or heart attack to
prevent further clotting
• Indications (low-dose aspirin, 81 mg to 325 mg a day):
prevent clots associated with stroke and heart attack; can
be used during a heart attack to keep clots from
completely occluding blood vessels in the heart
• Routes: all are oral; dipyridamole is also IV; aspirin is also
rectal
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Clotting Disorders
Antiplatelet Agents (continued)
• Side Effects (aspirin, common): bleeding, stomach upset,
headache, dizziness, and rash
 Side effects of clopidogrel and ticlopidine similar to
aspirin
• Side Effects: do not take antiplatelet agents if have or are
at risk for bleeding disorders, or have a history of ulcers
• Cautions: contraindicated in patients with bleeding
disorders or a history of ulcers; avoid taking
with NSAIDs
• Consideration: work best when taken with food
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Clotting Disorders
Thrombolytic Agents
• Indications: massive MI, stroke, PE (limited to lifethreatening situations due to high risk of severe bleeding)
 Used when immediate return of blood flow is crucial
• Mechanism of Action: break up clots that have already
formed; many dissolve and shrink blood clots
• Side Effects: bleeding, bruising, decreased heart rate and
blood pressure, arrhythmias, fever, allergic reactions
• Route: IV in inpatient setting
• Cautions (reteplase): protect from light; refrigerate
• Caution (tenecteplase): mix with sterile water only
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Clotting Disorders
Hemophilia Agents
• Drugs replace specific missing clotting factors
 This allows the coagulation cascade to function and
restores normal coagulation
• These injectable hemophilia agents include factors VIIa,
VIII, IX, and Von Willebrand factor
• Technicians will not prepare or dispense agents unless they
work in a specialty pharmacy; few pharmacies stock them
• Agents are costly; they are monitored by prescribers and
insurance providers
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Your Turn
Question 1: A patient is being treated for a blood clot. She was
initially given IV heparin, and then a LMWH product. What drug
therapy is likely to happen next?
Answer: She likely will begin oral warfarin therapy but must
overlap for at least five days with either heparin or LMWH.
Once the warfarin is at therapeutic range, she can take the
drug alone.
Question 2: What are two restrictions of antiplatelet agents?
Answer: Patients should not take these agents if they have
bleeding, are at risk for bleeding, or have a history of ulcers.
In addition, they should not take antiplatelet agents with
NSAIDs.
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Herbal and Alternative Therapies
• Few herbal or natural products are taken for blood
disorders
• Vitamin C is sometimes prescribed along with iron to boost
absorption
• Numerous herbal products interact with anticoagulants
(warfarin) and antiplatelet agents (aspirin and ticlopidine)
 To avoid drug interactions, technicians should
 take complete medical histories of patients on
blood clotting medications
 remind patients to inform healthcare providers
when they take herbal or natural products
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Summary
• Drug therapy for anemia includes iron, folic acid, and
vitamin B12 supplementation as well as hematopoietic
agents
• Costly missing clotting factors are used for hemophilia
• Blood clots can cause stroke, heart attack, PE, and DVT
• Anticoagulants and antiplatelet drug therapies are often
used to prevent and treat blood clots
• Thrombolytic drugs can be used in certain situations to
break down clots that have formed; costly and many risks
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