Drugs Used In Disorder Of Coagulation

Introduction

Hemostasis is spontaneous arrest of bleeding from a damaged blood vessel. Steps: Vascular injury à vasospasmà platelate adhesionà platelate aggregation à coagulation cascadesà fibrin formation

Anticoagulants are the drugs which inhibit fibrin formation.

Classification

Based on mechanism of action

1. Fast and direct acting e.g: Heparin
2. Slow and indirect acting

• Oral anticoagulants

e.g Warfarin and Dicumarol

Heparin

It is a heterogeneous mixture of sulfated mucopolysaccharides

Mechanism of action

Heparin activates antithrobimin III (AT III) which inhibits clotting factor proteases and hence it inhibits the formation of fibrin clots, inhibits the conversion of fibrinogen to fibrin, and inactivates several of the factors necessary for the clotting of blood.

Clinical Uses

Prevention and treatment of venous thrombosis, atrial fibrillation with embolus formation, prevention of post operative thrombosis and embolism, in open heart surgery, in arterial embolus, treatment of coronary occlusion, acute myocardial infarction and peripheral arterial embolism

Administration:

Can be given IV or subcutaneous. Oral therapy is ineffective because it is inactivated by gastric acids and absorption is minimal because of large molecular size.Heparin must never be administered intramuscularly because of danger of hematoma formation at injection site.

Side effects:

Bleeding is the major side effect, allergy, alopecia, osteoporosis and thrombocytopenia

Contraindications

Contraindicated in patients who are hypersensitive to the drug, are actively bleeding or have hemophilia, thrombocytopenia, purpura, sever hypertension, intracranial hemorrhage, infective endocarditis, active tuberculosis, etc.