2© paradigm publishing, inc. chapter 13 the blood and drug therapy

© Paradigm Publishing, Inc. 2

Chapter 13

The Blood and Drug Therapy


Chapter 13

Topics

• Anatomy and Physiology of the Blood• Anemia• Stroke• Clotting Disorders• Herbal and Alternative Therapies


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



Blood Composition• Cells or formed elements (45%)

Erythrocytes, leukocytes, platelets• Plasma (55%)

Water, proteins, and other substances



Blood Composition (continued)



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



Platelets and Blood Clot Formation• Tissue damage

triggers platelets to accumulate and activates clotting factors to start coagulation



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



Coagulation Cascade (continued)



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


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


Anemia

Anemia Types Description

Hemolytic Anemia

Rapid destruction of RBCs due to infection, drug therapy; blood loss often requires transfusion

Iron-deficiency Anemia

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


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


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


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


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


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


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.


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


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


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


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


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


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


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


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


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


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


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

© Paradigm Publishing, Inc.

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

31


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)


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


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


Clotting Disorders

Thrombolytic Agents • Indications: massive MI, stroke, PE (limited to life-

threatening 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


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


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.


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


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

2© paradigm publishing, inc. chapter 13 the blood and drug therapy

Documents

blood blood cells

blood paradigm publishing

blood blood composition

blood symptoms

anemia paradigm publishing

coagulation slide

matching of donor blood

hct blood values