Anticoagulants Anticoagulants are drugs used to prevent and

Anticoagulants

Anticoagulants are drugs used to prevent and treat venous thrombosis (DVT) Tow classes: Parenteral & Oral Parenteral anticoagulants: Heparin and enoxaparin MOA: Antithrombin effect thrombin Fibrinogen fibrin

Heparin is given I. V; S. C; I. M; I. V infusion; pumps. Heparin is effective in vivo & vitro Heparin major side effects: Bleeding. Management, stop drug and give a specific antidote to heparin protamine sulfate I. V Heparin contraindications: - Any bleeding tendency - Peptic ulcer disease

Low molecular weight heparin Enoxaparin Similar to heparin but more potent Has low M. W Associated with lower incidence of bleeding Its side effects and contraindications are similar to heparin

Oral anticoagulants: Warfarin, phenindione (coumarins) MOA: Have an antivitamin K effect, inhibiting synthesis of vitamin K-dependent clotting factors. Effective only in vivo Given orally Start acting in 2 -3 days (have delayed OOA)

Extensively bind plasma proteins (site of drug-drug interactions) Many antibiotics, aspirin…↑ activity of warfarin, barbiturates ↓ its activity Warfarin is usually given with heparin (at the same time) Warfarin side effects: Bleeding, management, stop drug and give its specific antidote, vitamin K I. V

Warfarin contraindications: - Bleeding tendencies - Peptic ulcer disease - During pregnancy Warfarin crosses easily the placenta and could lead to fetal abnormalities Heparin is not contraindicated during pregnancy (doesn’t cross the placenta)

Arterial thrombosis Management: - Eliminate risk factors, ↑ B. P; D. M; smoking; ↑ lipids… - Use of antiplatele drugs, aspirin; clopidogrel; dipyridamole… - Use of fibrinolytic (thrombolytic) drugs

Fibrinolytic (thrombolytic) drugs Drugs that activate plasminogen. Convert plasminogen to plasmin → breaks down fibrin Streptokinase, given in an I. V infusion Alteplase (tissue plasminogen activatort. PA), given in an I. V infusion Anistreplase, given I. V

Clinical uses of fibrinolytic drugs: - Pulmonary embolism - Acute M. I - Central DVT Disadvantages of fibrinolytic drugs: - Expensive - Frequent allergic reactions - Lead to bleeding