ppt chapter 48

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Drugs Affecting Blood Coagulation

Drugs Affecting Blood Coagulation

Chapter 48


Process of Blood CoagulationProcess of Blood Coagulation


Blood Vessel InjuryBlood 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

Damaged Vessel Endothelium is a Stimulus to Platelets, Causing Platelet

Adhesion


Types of Blood DisordersTypes 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 AnticoagulantsActions 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


AntiplateletAntiplatelet• 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.)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


QuestionQuestion

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


AnswerAnswer

B. Alter the formation of the platelet plug

Rationale: Antiplatelets alter the formation of the platelet plug.


Anticoagulants and Their IndicationsAnticoagulants 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.)

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 Anticoagulants

• Actions

– Interfere with the normal cascade of events involved in the clotting process


– Different based on the drug

• Contraindications

– Allergy and condition that could be compromised by increased bleeding tendencies

– Pregnancy, renal, or hepatic disorders


Anticoagulants (cont.)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.)Anticoagulants (cont.)


– Heparin and oral anticoagulants, salicylates, penicillins, or cephalosporins

– Heparin and nitroglycerine

– Warfarin – Number of documented interactions


Low-Molecular-Weight HeparinsLow-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 AgentsThrombolytic 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.)Thrombolytic Agents (cont.)• Contraindications

– 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.)Thrombolytic Agents (cont.)


– Anticoagulants

– Antiplatelet


QuestionQuestion

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


AnswerAnswer

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

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.


AntihemophilicAntihemophilic

• 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.)Antihemophilic (cont.)


– Allergy

– Factor IX in the presence of liver disease

– Lactation

• Caution

– Pregnancy


Antihemophilic (cont.)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 AgentsSystemic 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.)Systemic Hemostatic Agents (cont.)


– Allergy

– Acute DIC

• Caution

– Cardiac disease, renal or hepatic dysfunction, pregnancy and lactation


Systemic Hemostatic Agents (cont.)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

Use of Drugs Affecting Coagulation Across the Lifespan


QuestionQuestion

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.


AnswerAnswer

False

Rationale: Indications for a systemic hemostatic agent prevents or treats excess bleeding in hyperfibrinolytic

states.


Prototype AntiplateletsPrototype Antiplatelets


Prototype AnticoagulantsPrototype Anticoagulants


Prototype Anticoagulants (Continued)Prototype Anticoagulants (Continued)


Prototype Thrombolytic AgentsPrototype Thrombolytic Agents


Prototype AntihemophilicPrototype Antihemophilic


Prototype Systemic Hemostatic Agents Prototype Systemic Hemostatic Agents


Nursing Considerations for Antiplatelet Drugs

Nursing Considerations for Antiplatelet Drugs

• Assessment: History and Physical Exam

• Nursing Diagnosis

• Implementation

• Evaluation


Nursing Considerations for Anticoagulants

Nursing Considerations for Anticoagulants



• Implementation

• Evaluation


Nursing Considerations for Thrombolytic Agents

Nursing Considerations for Thrombolytic Agents



• Implementation

• Evaluation


Nursing Considerations for Antihemophilic Agents

Nursing Considerations for Antihemophilic Agents



• Implementation

• Evaluation


Nursing Considerations for Systemic Hemostatic Agents

Nursing Considerations for Systemic Hemostatic Agents



• Implementation

• Evaluation


QuestionQuestion

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


AnswerAnswer

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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