1. 23
Anticoagulants

2. Hemostasis: Three Events After Injury
Vascular spasms: platelets release serotonin, which causes blood vessel to spasm and decrease blood loss until clotting occurs
Platelet plug: platelets become sticky and adhere to vessel lining and each other, forming platelet plug, which is invaded by clotting factors

3. Hemostasis: Three Events After Injury
Coagulation: clot forms through chemical reactions that create netlike structure of fibrin, sealing off opening in injured vessel

4. Figure Hemostasis begins when a blood vessel is damaged and ends when the fibrin threads trap blood cells, forming a clot that seals the injured vessel.

5. Figure 23-2 Basic steps of hemostasis.

6. Mechanism of Action: Hemostasis
Involves 11 plasma proteins (clotting factors)
Most clotting proteins synthesized by liver
Prothrombin activator, prothrombin, thrombin, fibrinogen, fibrin

7. Figure 23-3 The steps in the coagulation cascade.

8. Anticoagulants Medications that prolong bleeding time
Do not dissolve clots already formed, but may prevent clots from becoming larger
Used to treat MI, venous thrombosis, pulmonary emboli
Primarily used for thrombosis in veins

9. Table 23-1 Anticoagulants

10. Heparin: Uses
Works by increasing length of coagulation; inhibits thrombi from forming or growing larger
Treat emboli, thrombi, MI, and to prevent clotting during open-heart surgery, coronary artery bypass graft, and dialysis

11. Heparin: Adverse Effects
Hemorrhage in urinary or GI tracts, subdural hematomas, hemorrhagic pancreatitis, hemarthrosis, ecchymosis

12. Heparin: Contraindications
Contraindicated in serious and intracranial bleeding, severe liver or kidney disease, malignant hypertension
Interacts with aspirin, NSAIDs, anesthetics, valproic acid, thrombolytics, and other drugs

13. Heparin: Patient Information
Teach patients how to administer heparin subcutaneously.
Advise patients to protect themselves from injury (e.g., use electric shaver).
Warn patients to avoid aspirin and other OTC drugs.
Instruct patients to report signs of bleeding.

14. Heparin in Older Adults
Older adults are more susceptible to effects of anticoagulants. Signs of overdose include epistaxis, blood in stool or urine, excessive bruising, and prolonged bleeding.
Overdose can be treated by slow infusion of 1% protamine sulfate.

15. Figure 23-4 Mechanism of action of anticoagulants.

16. LMWH: Uses Greater bioavailability and longer action than heparin
More effective in preventing and treating venous thromboembolism
Less bleeding and fewer episodes of heparin-induced thrombocytopenia

17. Table 23-2 Common Low-Molecular-Weight Heparins

18. Warfarin (Coumadin): Uses
Interferes with hepatic synthesis of vitamin K-dependent clotting factors (II, VII, IX, X)
Used on inpatient and outpatient basis for long-term anticoagulation

19. Warfarin: Adverse Effects
Hemorrhage
Diarrhea
Urticaria
Alopecia
Skin necrosis
Dermatitis

20. Warfarin: Contraindications
Contraindicated in active or previous ulceration, hepatic or renal disease, malignant hypertension, bacterial endocarditis, chronic alcoholism, pregnancy
Interacts with hepatic enzyme inhibitors, aspirin, NSAIDs, and thrombolytics

21. Warfarin: Patient Information
Instruct patients to report signs of bleeding; chest, abdominal, lumbar, or pelvic pain.
Advise patient to stop drug immediately if signs of hepatitis occur.
Advise female patients to avoid pregnancy with barrier contraceptive and to avoid breastfeeding.

22. Warfarin Tips for Patients
Advise patients that 5 days prior to dental procedures, warfarin should be stopped.
Supplemental intake of vitamin K can potentiate or inhibit oral anticoagulants.

23. Antiplatelets: Uses Prevent platelets from binding together
Used to prevent clot formation in arteries, in MI and stroke, and in PCTA
Aspirin: low doses inhibit platelet aggregation and prolong bleeding time
Ticlopidine (Ticlid) and clopidogrel (Plavix) irreversibly inhibit platelet activation

24. Antiplatelets: Uses
Abciximab (ReoPro), eptifibatide (Integrilin) and tirofiban (Aggrastat) interrupt interaction of fibrinogen with clotting factors

25. Table 23-3 Antiplatelet Agents

26. Antiplatelets: Adverse Effects
Epigastric pain, heartburn, nausea, diarrhea, major or minor bleeding
Abciximab: cardiac arrhythmias, abnormal thoughts, dizziness

27. Antiplatelets: Contraindications
Contraindicated in patients with history of peptic ulcer, hypertension, asthma, allergies, nasal polyps
Interact with anticoagulants, thrombolytic agents, dextran, and other drugs

28. Antiplatelets: Patient Information
Instruct patients to report nausea, diarrhea, rash, sore throat, or infections; signs of bleeding; signs of hepatitis.
Advise patients to avoid aspirin and antacids.

29. Garlic as Anticoagulant
Garlic has been shown to decrease platelet aggregation.
Use of garlic with anticoagulants may increase risk of bleeding complications.

30. Thrombolytics: Uses
Used to prevent or treat excessive bleeding from surgical sites
Facilitate conversion of plasminogen to plasmin, which hydrolyzes fibrin to dissolve blood clots
Also called plasminogen activators

31. Table Thrombolytics

32. Thrombolytics: Adverse Effects
Common: bleeding caused by fibrinogenolysis or fibrinolysis at site of injury
Serious: intracranial bleeding

33. Thrombolytics: Contraindications
Contraindicated in active bleeding, pregnancy, lactation, intracranial trauma, vascular disease, and cancer
Interact with anticoagulants, aspirin, and herbs such as feverfew, ginger, and ginkgo

34. Thrombolytics: Patient Information
Instruct patients to report signs of bleeding or changes in consciousness.
Advise women to avoid breastfeeding.

35. Thrombocytopenia
Platelet deficiency; most common cause of abnormal bleeding
Hemophilia applies to several hereditary bleeding disorders that result from lack of factors needed for clotting.