ANTICOAGULANTS : ANTICOAGULANTS BATCH-G4
NIKITA NATH COAGULATION : COAGULATION Coagulation is a complex process by which blood forms clots. It is an important part of hemostasis (the cessation of blood loss from a damaged vessel), wherein a damaged blood vessel wall is covered by a platelet and fibrin-containing clot to stop bleeding and begin repair of the damaged vessel.
Disorders of coagulation can lead to an increased risk of bleeding (hemorrhage) or clotting (thrombosis). 2 THE COAGULATION CASCADE : THE COAGULATION CASCADE 3 COAGULANTS : COAGULANTS These are substances which promote coagulation, and are indicated in haemorrhagic states.
Fresh whole blood or plasma provide all the factors needed for coagulation and are best therapy for deficiency of any clotting factor.
They also act immediately. 4 VITAMIN K : VITAMIN K It is a fat soluble dietary principle required for the synthesis of clotting factors.
Dietary sources are-green leafy vegetables, such as cabbage,spinach and liver, cheese, etc.
Vit K acts as a cofactor in the synthesis of coagulation proteins-prothrombin, factors vii, ix and x.
The vit K dependent change confers on them the capacity to bind Calcium and to get bound to phospholipid surfaces. 5 DEFICIENCY : DEFICIENCY Deficiency of vit K occurs due to :-
Long-term antimicrobial therapy
Deficient diet 6 ANTICOAGULANTS : ANTICOAGULANTS An anticoagulant is a drug that helps prevent the clotting (coagulation) of blood.
These drugs tend to prevent new clots from forming or an existing clot from enlarging.
They don't dissolve a blood clot.
Anticoagulants are also given to certain people at risk for forming blood clots, such as those with artificial heart valves or who have atrial fibrillation. 7 CLASSIFICATION : CLASSIFICATION Used in vivo:-
Danaparoid,Lepirudin,Ancrod. 8 Slide 9: Oral anticoagulants:
Phenindione 9 : Used in vitro:-
A. Heparin(150 U to prevent clotting of 100 ml blood.)
B. Calcium complexing agents:-
Sodium citrate(1.65 g for 350 ml of blood)
Sodium oxalate(10 mg for 1 ml blood) 10 HEPARIN : HEPARIN McLean, a medical student ,discovered in 1916 that liver contains a powerful anticoagulant.
Howell and Holt in 1918 named it ‘HEPARIN’
because it was obtained from liver. 11 CHEMISTRY OF HEPARIN : CHEMISTRY OF HEPARIN Heparin is a non-uniform mixture of straight chain mucopolysaccharides with MW 10,000 to 20,000.
It contains polymers of two sulfated disaccharide units:
It carries strong electronegative charges and is the strongest organic acid present in the body. 12 OCCURRENCE OF HEPARIN : OCCURRENCE OF HEPARIN Heparin is found in the secretory granules of mast cells.Thus ,heparin is present in all tissues containing mast cells;richest sources are lung,liver and intestinal mucosa.
Commercially it is produced from ox lung and pig intestinal mucosa. 13 PHARMACOLOGICAL ACTIONS : PHARMACOLOGICAL ACTIONS ANTICOAGULANT:-
Heparin is a powerful and instantaneously acting anticoagulant, effective both in vivo and in vitro.
Heparin produces its anticoagulant effect by activating plasma antithrombin iii(AT III a serine proteinase inhibitor) and may be other similar cofactors. 14 MECHANISM OF ACTION : MECHANISM OF ACTION 15 Inactivation of clotting enzymes by heparin : Inactivation of clotting enzymes by heparin 16 ROLE OF HEPARIN/ATIII COMPLEX : ROLE OF HEPARIN/ATIII COMPLEX 17 ACTIONS : ACTIONS 2. ANTIPLATELET:-
Heparin in higher doses inhibits platelet aggregation and prolongs bleeding time.
3. LIPAEMIA CLEARING:-
Injection of heparin clears turbid post-prandial lipaemic by releasing a lipoprotein lipase from the vessel wall and tissues,which hydrolyses triglycerides of chylomicra and very low density lipoproteins to free fatty acids;these then pass into tissues and the plasma looks clear. 18 PHARMACOKINETICS : PHARMACOKINETICS Heparin is a large, highly ionized molecule; therefore not absorbed orally.
Injected i.v. it acts instantaneously,but after s.c. injection anticoagulant effect develops after 60 min.
Heparin does not cross blood-brain barrier or placenta.
It is metabolized in liver by heparinase and fragments are excreted in urine.Heparin released from mast cells is degraded by tissue macrophages. 19 ADVERSE EFFECTS : ADVERSE EFFECTS Bleeding due to overdose is the most serious complication of heparin therapy.Haematuria is generally the first sign.
Thrombocytopenia is another common problem.
Transient and reversible alopecia is infrequent.
Osteoporosis may develop on long-term use of relatively high doses.
Hypersensitivity reactions are rare. 20 CONTRAINDICATIONS : CONTRAINDICATIONS Bleeding disorders,heparin induced thrombocytopenia.
Severe hypertension,threatened abortion, piles,g.i.ulcers.
Subacute bacterial endocarditis, large malignancies,tuberculosis.
Chronic alcoholics, cirrhosis, renal failure.
Aspirin and other antiplatelet drugs should be used very cautiously during heparin therapy. 21 HEPARIN ANTAGONIST : HEPARIN ANTAGONIST Protamine sulfate:-
It is a strongly basic, low molecular weight protein obtained from the sperm of certain fish.
Given i.v. it neutralises heparin weight for weight,i.e. 1 mg is needed for every 100 U of heparin.
In the absence of heparin, protamine itself acts as a weak anticoagulant by interacting with platelets and fibrinogen. 22 ORAL ANTICOAGULANTS : ORAL ANTICOAGULANTS Oral anticoagulants are medicines used for people who are at risk of developing abnormal blood clotting.
The oral anticoagulants are a class of pharmaceuticals that act by antagonizing the effects of vitamin K.
Abnormal blood clotting can occur in arteries, veins or heart. Clotting in the brain vessels leads to stroke while in the heart vessels causes heart attack.
Clotting in the limb vessels can cause gangrene.
Clots can dislodge and go to the lungs, known as pulmonary embolism. 23 EXAMPLES OF ORAL ANTICOAGULANTS : EXAMPLES OF ORAL ANTICOAGULANTS Recemic Warfarin sodium
Phenindione 24 WARFARIN : WARFARIN Warfarin is a synthetic derivative of coumarin, a chemical found naturally in many plants, like, woodruff (Galium odoratum, Rubiaceae), and at lower levels in licorice, lavender, species.
Warfarin is prescribed to people with an increased tendency for thrombosis or in those individuals that have already formed a blood clot (thrombus).
Warfarin is contraindicated in pregnancy, as it passes through the placental barrier and may cause bleeding in the fetus. 25 MECHANISM OF ACTION : MECHANISM OF ACTION Warfarin inhibits the vitamin K-dependent synthesis of biologically active forms of the calcium-dependent clotting factors II, VII, IX and X, as well as the regulatory factors protein C. 26 ADVERSE EFFECTS Hemorrhage
Purple toe syndrome MECHANISM OF ACTION : MECHANISM OF ACTION 27 ADVERSE EFFECTS : ADVERSE EFFECTS Bleeding
TREATMENT: give fresh blood transfusion, supplies clotting factors & replenishes lost blood.
Give vit K-specific antidote but it takes 6-24 hours for clotting factors to be resynthesised & released in blood after vit K administration. 28 Slide 29: 29 USES OF ANTICOAGULANTS : USES OF ANTICOAGULANTS The aim of using anticoagulants is to prevent thrombus extension and embolic complications by reducing the rate of fibrin formation.
USES:- 1.Deep vein thrombosis and pulmonary embolism.
4.Rheumatic heart disease;Atrial fibrillation 30 USES : USES 5.Cerebrovascular disease
6.Vascular surgery, prostatic heart valves,retinal vessel thrombosis,extracorporeal circulation, haemodialysis.
7.Defibrination syndrome 31 Slide 32: THANKS 32