Ppt chapter 48

Drugs Affecting Blood
Coagulation
Chapter 48

Process of Blood Coagulation

Blood Vessel Injury
• Local vasoconstriction seals off small injury
• Platelet aggregation forms a platelet plug
• Hageman factor is activated
• Intrinsic pathway converts prothrombin to thrombin to
seal system
• Extrinsic pathway clots the blood that has leaked out of
the vascular system

Damaged Vessel Endothelium is a
Stimulus to Platelets, Causing Platelet
Adhesion

Types of Blood Disorders
• Thromboembolic Disorder
– Conditions that predispose a person to the formation
of clots and emboli
• Hemorrhagic Disorder
– Disorder in which excess bleeding occurs

Actions of Anticoagulants
• Anticoagulants
– Interfere with the clotting cascade and thrombin
formation
• Antiplatelets
– Alter the formation of the platelet plug
• Thrombolytic Drugs
– Break down the thrombus that has been formed by
stimulating the plasmin system

Antiplatelet
• Actions
– Inhibit platelet adhesion and aggregation by blocking receptors
sites on the platelet membrane
– Anagrelide – Blocks the production of platelets in the bone
marrow
• Indications
– Reduce risk of recurrent TIAs or strokes; reduce death or
nonfatal MI; MI prophylaxis; anti-inflammatory, analgesic, and
antipyretic effects
• Pharmacokinetics
– Well absorbed and bound to plasma proteins
– Metabolized in the liver and excreted in the urine

Antiplatelet (cont.)
• Contraindications
– Allergy, pregnancy, and lactation
• Caution
– Bleeding disorder, recent surgery, closed-head injury
• Adverse Effects
– Bleeding
– Headache, dizziness, and weakness
– GI distress
• Drug-to-Drug Interactions
– Another drug that affects blood clotting

Question
How do antiplatelet medications work?
A. Interfere with the clotting cascade
B. Alter the formation of the platelet plug
C. Stimulates the plasmin system
D. Initiates the clotting cascade

Answer
B. Alter the formation of the platelet plug
Rationale: Antiplatelets alter the formation of the platelet
plug.

Anticoagulants and Their Indications
• Warfarin (Coumadin)
– Maintains a state of anticoagulation when patient is
susceptible to potentially dangerous clot formation
• Heparin (Generic)
– Inhibits the conversion of prothrombin to thrombin
• Antithrombin (Thrombate III)
– Used for hereditary antithrombin III deficiencies;
replacement therapy in congenital antithrombin III
deficiency

Anticoagulants and Their Indications
(cont.)
• Argatroban (Acova)
– Used to treat thrombosis in heparin-induced
thrombocytopenia
• Bivalirudin (Angiomax)
– Used with aspirin to prevent ischemic events in
patients undergoing transluminal coronary
angioplasty

Anticoagulants
• Actions
– Interfere with the normal cascade of events involved in
the clotting process
– Different based on the drug
– Allergy and condition that could be compromised by
increased bleeding tendencies
– Pregnancy, renal, or hepatic disorders

Anticoagulants (cont.)
• Caution
– CHF, thyrotoxicosis, senility, or psychosis
• Adverse Effects
– Bleeding
– GI upset
– Hepatic dysfunction
– Alopecia, dermatitis, bone marrow suppression,
prolonged, and painful erection

Anticoagulants (cont.)
– Heparin and oral anticoagulants, salicylates,
penicillins, or cephalosporins
– Heparin and nitroglycerine
– Warfarin – Number of documented interactions

Low-Molecular-Weight Heparins
• Inhibit thrombus and clot formation by blocking factors
Xa and Iia
• Do not greatly affect thrombin, clotting, or prothrombin
times; therefore cause fewer systemic adverse effects
• Block angiogenesis, the process that allows cancer cells
to develop new blood vessels
• Are indicated for specific uses in the prevention of clots
and emboli formation after certain surgeries or bed rest

Thrombolytic Agents
• Actions
– Activating plasminogen to plasmin, which in turn
breaks down fibrin threads in a clot to dissolve a
formed clot
• Indications
– Acute MI, pulmonary emboli, ischemic stroke
– Drugs must be injected and are cleared from the
body after liver metabolism
– Pregnancy and lactation

Thrombolytic Agents (cont.)
– Allergy
– Any condition that would be worsened by dissolution
of clots
• Adverse Effects
– Bleeding
– Cardiac arrhythmias
– Hypotension
– Hypersensitivity – Rash, flushing, bronchospasm, and
anaphylactic reaction

Thrombolytic Agents (cont.)
– Anticoagulants
– Antiplatelet

Question
The pharmacology instructor is talking to the student about
low-molecular-weight-heparin medications. What would
the instructor indicate as an advantage to these
medications?
A. Indicated for patients who are on an exercise regimen
B. Initiates angiogenesis
C. Blocking factors IXa and Iaa
D. Cause fewer systemic adverse effects

Answer
D. Cause fewer systemic adverse effects
Rationale: Low-molecular-weight-heparins do not greatly
affect thrombin, clotting, or prothrombin times; therefore
cause fewer systemic adverse effects.

Bleeding Disorders Treated With Clotting
Factors
• Hemophilia
– Genetic lack of clotting factors that leaves the patient
vulnerable to excessive bleeding with any injury.
• Liver Disease
– Clotting factors and proteins needed for clotting are
not produced.
• Bone Marrow Disorders
– Platelets are not formed in sufficient quantity to be
effective.

Antihemophilic
• Actions
– Replace clotting factors that are either genetically
missing or low in a particular type of hemophilia
• Indications
– Prevent blood loss from injury or surgery and to treat
bleeding disorders
– Replace normal clotting factors and are processed as
such by the body

Antihemophilic (cont.)
– Allergy
– Factor IX in the presence of liver disease
– Lactation
• Caution
– Pregnancy

Antihemophilic (cont.)
• Adverse Effects
– Involve risks associated with the use of blood
products
– Headache, flushing, fever, chills, lethargy
– Nausea and vomiting
– Stinging, itching, and burning at the site of injection

Systemic Hemostatic Agents
• Actions
– Stop the natural plasminogen clot-dissolving
mechanism by blocking its activation or by directly
inhibiting plasmin.
• Indications
– Prevent or treat excess bleeding in hyperfibrinolytic
states
– Different for each drug

Systemic Hemostatic Agents (cont.)
– Allergy
– Acute DIC
• Caution
– Cardiac disease, renal or hepatic dysfunction,
pregnancy and lactation

Systemic Hemostatic Agents (cont.)
• Adverse Effects
– Excessive clotting
– CNS – Hallucinations, drowsiness, dizziness, headache,
and psychotic states
– GI – Nausea, cramps, diarrhea
– Weakness, fatigue, malaise, and muscle pain
– Aprotinin – Cardiac arrhythmias, MI, CHF, and
hypotension
– Heparin
– Oral contraceptives or estrogen

Use of Drugs Affecting Coagulation Across
the Lifespan

Question
Please answer the following statement as true or false.
The indications for use of a systemic hemostatic agent is to
prevent blood loss from injury or surgery and to treat
bleeding disorders.

Answer
False
Rationale: Indications for a systemic hemostatic agent
prevents or treats excess bleeding in hyperfibrinolytic
states.

Prototype Antiplatelets

Prototype Anticoagulants

Prototype Anticoagulants (Continued)

Prototype Thrombolytic Agents

Prototype Antihemophilic

Prototype Systemic Hemostatic Agents

Nursing Considerations for Antiplatelet
Drugs
• Assessment: History and Physical Exam
• Nursing Diagnosis
• Implementation
• Evaluation

Nursing Considerations for Anticoagulants
• Implementation
• Evaluation

Nursing Considerations for Thrombolytic
Agents
• Implementation
• Evaluation

Nursing Considerations for Antihemophilic
Agents
• Implementation
• Evaluation

Nursing Considerations for Systemic
Hemostatic Agents
• Implementation
• Evaluation

Question
You are writing a care plan on a patient who is taking an
anticoagulant. What would be an appropriate nursing
diagnosis?
A. Evaluate patient for PT > 2.5
B. Establish safety precautions
C. Notify the health care provider of any patient receiving
this drug
D. Maintain narcan on standby

Answer
B. Establish safety precautions
Rationale: Patients on anticoagulants are at increased risk
for bleeding. The following are all important steps to
protect the patient from blood loss: using soft-bristled
toothbrushes, using electric instead of straight razors,
avoiding activities that could easily involve injury,
limiting invasive procedures, and ensuring adequate
compression to stop bleeding.

Ppt chapter 48

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Ppt chapter 48