CLASSICATION OF ANTICOAGULANT DRUGS

CLASSICATION OF ANTICOAGULANT DRUGS

CLASSICATION OF ANTICOAGULANT DRUGS

1. Direct Acting Anticoagulants

a) Calcium Chelators (sodium citrate, EDTA)

b) Heparin

2. Indirect Acting Anticoagulant Drugs

a) Warfarin

Related Questions Blood Disorders

COAGULANTS

An agent that produces coagulation (Coagulation is a complex process by which blood forms clots).

ANTICOAGULANTS

An anticoagulant is a substance that prevents coagulation; that is, it stops blood from clotting.

 

Anticoagulants:

Calcium Chelators (sodium citrate, EDTA)

Heparin

Dalteparin Sodium (Fragmin) -Low molecular-weight heparin

Enoxaparin - Low molecular-weight heparin

Tinzaparin Sodium  - Low molecular-weight heparin

Warfarin

Lepirudin - recombinant form of the natural anticoagulant hirudin: potent and specific Thrombin inhibitor

Bivalirudin - analog of hirudin: potent and specific Thrombin inhibitor

Procoagulants:

Desmopressin acetate

Antiplatelet Drugs:

Acetylsalicylic Acid, Ticlopidine, Sulfinpyrazone, Abciximab , Clopidogrel bisulfate

Fibrinolytic Drugs:

Tissue Plasminogen Activator (t-PA, Activase), Streptokinase (Streptase),

Anistreplase, Urokinase

 

Antagonists:

Protamine sulfate, Aminocaproic acid

Pharmacological agents used to treat blood coagulation disorders fall in to three major categories:

1. Anticoagulants: Substances that prevent the synthesis of a fibrin network which inhibits coagulation and the formation of arterial thrombi and thromboembolic clots.

2. Antiplatelet agents: Substances that reduce the adhesion and aggregation of platelets.

3. Fibrinolytic agents: Substances that promote the destruction of already formed blood clots or thrombi by disrupting the fibrin mesh.

Thrombolytic Agents:

Tissue Plasminogen Activator (t-PA, Activase)

t-PA is a serine protease. It is a poor plasminogen activator in the absence of fibrin. t-PA binds to fibrin and activates bound plasminogen several hundred-fold more rapidly than it activates plasminogen in the circulation.

Streptokinase (Streptase)

Streptokinase is a protein produced by β-hemolytic streptococci. It has no intrinsic enzymatic activity, but forms a stable noncovalent 1:1 complex with plasminogen. This produces a conformational change that exposes the active site on plasminogen that cleaves a peptide bond on free plasminogen molecules to form free plasmin.

Urokinase (Abbokinase)

Urokinase is isolated from cultured human cells.Like streptokinase, it lacks fibrin specificity and therefore readily induces a systemic lytic state. Like t-PA, Urokinase is very expensive.

Contraindications to Thrombolytic Therapy:

• Surgery within 10 days, including organ biopsy, puncture of noncompressible vessels, serious trauma, cardiopulmonary resuscitation.

• Serious gastrointestinal bleeding within 3 months.

• History of hypertension (diastolic pressure >110 mm Hg).

• Active bleeding or hemorrhagic disorder.

• Previous cerebrovascular accident or active intracranial bleeding.

Aminocaproic acid:

Aminocaproic acid prevents the binding or plasminogen and plasmin to fibrin. It is a potent inhibitor for fibrinolysis and can reverse states that are associated with excessive fibrinolysis.

CLASSICATION OF ANTICOAGULANT DRUGS

1. Direct Acting Anticoagulants

a) Calcium Chelators (sodium citrate, EDTA)

b) Heparin

2. Indirect Acting Anticoagulant Drugs

a) Warfarin

NATURAL ANTICOAGULANTS:

       1. PGI-2.

       2. Antithrombin.

       3. Protein-C.

       4. TFPI.

       5. Heparin.

       6. Fibrinolytic system.

Heparin:

  • Inhibits blood coagulation by forming complexes with an α2-globulin (Antithrombin III) and each of the activated proteases of the coagulation cascade (Kallikrein, XIIa, XIa, IXa, Xa, and Thrombin). After formation of the heparin-ATIII-coagulation factor, heparin is released and becomes available again to bind to free ATIII.
  • Blocks conversion of Prothrombin to Thrombin and thus inhibits the synthesis of Fibrin from Fibrinogen.
  • Inhibits platelet function and increases vascular permeability. May induce moderate to severe thrombocytopenia.
  • Is prescribed on a “unit” basis.
  • Heparin is not effective after oral administration and is generally administered by intravenous or subcutaneous injection. Intramuscular injections should be avoided.
  • Heparin does not cross the placenta and does not pass into the maternal milk.
  • is contraindicated in any situation where active bleeding must be avoided.

Ulcerative lesions, intracranial hemorrhage, etc.

Overdosage:

• Simple withdrawal.

• Protamine sulfate: Highly basic peptide that binds heparin and thus neutralizes its effects.