Ch. 52: Anticoagulants

Question 1

Heparin: Unfractionated

Answer 1

• enhances antithrombin which inactivates clotting factors thrombin and factor Xa = reduction of fibrin production and suppression of clotting
• rapid-acting anticoagulant
• admin by IV only
• uses: during pregnancy and when rapid anticoagulation is required, pulmonary embolism, stroke evolving, massive deep vein thrombosis, open heart surgery, renal dialysis, postop
• adverse: hemmorrhage, heparin-induced thrombocytopenia, hypersensitivity reactions (gills, fever, urticaria)
• contradicted: thrombocytopenia, uncontrollable bleeding, during and after surgery of eye, brain or spinal cord
• antidote for overdose: protamine sulfate
• monitor activated partial thromboplastin time (aPTT)

Question 2

Low-Molecular-Weight (LMW) Heparin

Answer 2

• uses: prevention of DVT after surgery- including replacement of hip, knee; treatment of established DVT; prevention of ischemic complications (unstable angina, MI, and STEM)
• adminster subQ
• dosage by body weight
• antidote: Protamine sulfate
• costs more than unfractionated heparin
• does not require monitoring (give at home)
• adverse: bleeding, immune-mediated thrombocytopenia, severe neurological injury for patients undergoing spinal puncture or spinal epidural anesthesia

Question 3

Warafin (coumadin)

Answer 3

• oral anticoagulant
• use: delayed onset; Vit K antagonist, blocks vit K epoxide reductase complex 1 (needed to convert Vit K to active form) = blocks biosynthesis of vit K dependent clotting factors and prothrombin
• therapuetic uses: not useful in emergencies; long-term prophylaxis of thrombosis, prevent venous thrombosis and associated pulmonary embolism, prevent thromboembolism, prevent thrombosis during artial fibrillation
• monitor prothrombin time (PT) and international normalized ratio
• adverse: hemorrhage, fetal/teratogenesis, lactation
• interactoins: drugs that increase anticoagulant effects, promote bleeding, decrease anticoagulant effects, Heparin, Aspirin, Acetaminophen
• beware of Vit K intake (mayonnaise, conal oil, green leafy veg)

Question 4

Aspirin

Answer 4

• uses: ischemic stroke, chronic stable angina, unstable angina, coronary stenting, acute MI, previous MI, prevent MI
• adverse: bleeding, GI bleed and hemorrhagic stroke, enteric-coated may not reduce the risk of GI bleed

Question 5

Abciximab (ReoPro)

Answer 5

• binds to platelets in the vincinity of GP receptors, preventing receptors from binding fibrinogen
• used with aspirin and heparin

Question 6

Tirofiban (Aggrastat)

Answer 6

• selective and reversible inhibition of GP receptors
• used to reduce ischemic events associated with ACS and PCI
• platelet function returns to normal within 4 hours and stopping the infusion
• bleeding si the primary adverse effect
• risk of bleeding can be increased by other drugs that suppress hemostasis

Question 7

Thrombolytics: Alteplase (tPA)

Answer 7

• binds with plasminogen to form an active complex
• plasmin digests fibrin meshwork of clots
• uses: MI, ischemic stroke, massive pulmonary emboli
• adverse: bleeding: risk for intrcranial bleeding, whole blood, aminocaproic acid; and fever
• advantages: does not cause allergic reactions and induced hypotension

Question 8

Minimize Risk of Bleeding

Answer 8

• minimize physical manipulation of the patient
• avoid subQ and IM injections
• min. invasive procedures
• min concurrent use of anticoagulants
• min. concurrant use of antiplatelet drugs