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Drugs Affecting Blood
Coagulation
Chapter 48
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Blood Vessel Injury
•
Local vasoconstriction seals off small injury
•
Platelet aggregation forms a platelet plug
•
Hageman factor is activated (factor XII)
•
Intrinsic pathway converts prothrombin to thrombin to
seal system
•
Extrinsic pathway clots the blood that has leaked out of
the vascular system
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Process of Blood Coagulation
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Damaged Vessel Endothelium is a
Stimulus to Platelets, Causing Platelet
Adhesion
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Types of Blood Disorders
•
Thromboembolic Disorder
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Conditions that predispose a person to the formation
of clots and emboli
•
Hemorrhagic Disorder
–
Disorder in which excess bleeding occurs
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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
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer
B. Alter the formation of the platelet plug
Rationale: Antiplatelets alter the formation of the platelet
plug.
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Actions of Anticoagulants
•
Anticoagulants
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Interfere with the clotting cascade and thrombin
formation
•
Antiplatelets
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Alter the formation of the platelet plug
•
Thrombolytic Drugs
–
Break down the thrombus that has been formed by
stimulating the plasmin system
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Antiplatelet
•
Abciximab (ReoPro)
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Anagrelide (Agrylin)
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Aspirin
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Cilostazol (Pletal)
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Clopidogrel (Plavix)
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Dipyridamole (Persantine)
•
Eptifibatide (Integrilin)
•
Ticlopidine (Ticlid)
•
Ticagrelor (Brilinta)
•
Tirofiban (Aggrastat)
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Antiplatelet (cont.)
•
Actions
–
Inhibit platelet adhesion and aggregation by blocking receptors
sites on the platelet membrane
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Anagrelide
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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
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Antiplatelet (cont.)
•
Contraindications
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Allergy, pregnancy, and lactation
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Caution
–
Bleeding disorder, recent surgery, closed-head injury
•
Adverse Effects
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Bleeding
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Headache, dizziness, and weakness
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GI distress
•
Drug-to-Drug Interactions
–
Another drug that affects blood clotting
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Prototype Antiplatelets
