Anticoagulants

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1. Pharmacology Slide-33 Anti-coagulants 2. Anti-coagulants  Drugs interfere with the clotting and are used to prevent and treat venous thrombosis.  Anti coagulants…
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  • 1. Pharmacology Slide-33 Anti-coagulants
  • 2. Anti-coagulants  Drugs interfere with the clotting and are used to prevent and treat venous thrombosis.  Anti coagulants include: 1.Heparin and it derivatives. 2.Coumarins : Warfarin and phenindione.
  • 3. Heparin  Is a complex mixture of acid substances. *inhibit coagulation by binding to antithrombin III. This binding enhance the action of antithrombin’s to enhance other clotting factors. *the net result is prolongation of clotting time. Clotting time : is the time needed for blood or plasma to coagulate under controlled lab conditions.
  • 4. Heparin Two preperations of heparin: 1.Unfractionated heparin 2.Low molecular weight heparin  Heparin is a large molecule, it can be breaking down into a number of fragments and those fragments that have anti-coagulant activity are known as low molecular weight heparin.
  • 5. Heparin Advantage of LMWH: 1.Better in preventing the venous thrombosis. 2.Given S.C and it is powerful as unfractionated heparin in prevention and treatment of pulmonary embolism. 3.Used with success in unstable angina. 4.It doesn’t cross placenta, so it can be given during pregnancy. 5.It has more prolonged effect than unfractionated heparin.
  • 6. Heparin Low molecular weight heparin given S.C once/twice daily and the dose is calculated according to the weight of the patient. The most common examples are: 1.Enoxaparin (Clexane®( 2.Daltaparin 3.Tinazapin (Innohep®(
  • 7. Heparin Heparin given by I.V or S.C only.  Rapid onset of effect within 1-2 minutes with duration of 4-6 hours.  Bcz of it’s rapid onset it is the first to be used as anticoagulant treatment.  Can be given as I.V infusion through infusion pump and the dilution is either saline or 5% dextrose.
  • 8. Heparin *The rate of infusion monitored by measuring the activated partial thromboplastin time (aPTT) , 6-hours after starting infusion at least once daily. *aPTT should be kept between 1.5 and 2.5 times the control value. *abdomen is the best site of injection.
  • 9. Heparin  Side effects: bleeding at high doses.  The first sign for bleeding mostly haematuria.  Prolonged use can cause osteoperosis.  Very rarely, thrombocytopenia.  Protamine sulphate reverse the action of heparin (antidote of heparin(.
  • 10. Coumarins  These are oral anticoagulats include: *Warfarin and phenindione. *Exert their action by the interfering with vitamin K-dependant clotting factors, especially factors VII, II, X and XI.
  • 11. Coumarins  Prothrombin time (PT) should be measured before starting treatment and the dose adjusted until the international normalized ratio (INR) between (depending on the clinical 2.0- 3.5situation(.  Side effects: 1.rashes, fever and jaundice. 2.Teratogenic effects. 3.hemorrhage.
  • 12. Coumarins  If hemorrhage happen it can be reverse rapidly by an infusion of fresh frozen plasma and phytomenadione (Vitamin K) ,also given as I.V but it takes 12 hours to become effective.
  • 13. Coumarins Notes: 1.Warfarin crosses the placenta and should not be given in the first 3 months of pregnancy. Instead we use heparin during pregnancy. 2.don’t give anti-coagulants in patients with active peptic ulcers, severe liver disease or renal failure. 3.Strict accuracy in the timing of dosing.
  • 14. Fibrinolytics 1.Streptokinase: *bind to plasminogen and activate it (used to treat coronary thrombosis(. It is given by I.V infusion.  premedications: 1.Hydrocortisone to reduce allergic reactions. 2.Loading dose of oral aspirin which should be chewed before swallowing.
  • 15. Fibrinolytics Side effects: 1.Bleeding 2.Allergies (fever( 3.Hypotension Note : patient develop antibodies of streptokinase in the body after 4 days of the treatment so the drug should not be used for at least 12 months after.
  • 16. Fibrinolytics 2.Alteplase: *it is a tissue plasminogen activator (tPA(. *streptokinase antibodies or streptococcal antibodies (in patient who has been infected by it) don’t affect alteplase. *maybe followed by heparin to prevent reocclusion.
  • 17. Fibrinolytics 3.Antistreplase: *it is a plasminogen-streptokinase complex. *given by I.V infusion over 4-5 min and fibrinolytics activity is sustained for 4-6 hours.
  • 18. Fibrinolytics -Not given by I.M injection.
  • 19. Antiplatelet drugs 1.Aspirin* prevent the production of thromboxane in platelets which causes the aggregation. *uses: 1.coronary thrombosis with streptokinase. 2.to prevent reoccurrence of coronary thrombosis. 3.in angina of effort. 4.in unstable angina to prevent the progression to M.I.
  • 20. Antiplatelet drugs 2.Dipyridamole (presantine®) (Antiplate®(: *it is not effective if given alone, combined with warfarine or aspirin. 3.Fish oil.
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