Types of Anticoagulants and Duration Following Venous Thromboembolism
Yasser Magdy Hamed Mohammed;
Abstract
Blood coagulation forms part of a series of haemostatic reactions, including plasma, platelets, and vascular components. Platelets adhere to the damaged endothelium or to the subendothelium under the effect of adhesive proteins, and after being activated they aggregate and expose binding sites for the coagulation factors. Therefore, platelets help to concentrate and potentiate the coagulation reactions on damaged blood vessels.
Following interaction of the 'contact' factors XI and XII, a cascade of activation occurs to the coagulation protease zymogens. This results in the conversion of fibrinogen to fibrin, the formation of thrombin and finally a platelet-fibrin plug. During healing process, fibrin deposition and removal is regulated by the fibrinolytic system.
Anticoagulants are considered the primary line for preventing and treating thrombosis. New oral anticoagulants such as rivaroxaban, apixaban and dabigatran are expected to replace the older drugs for being easier to use and for having better pharmacodynamic profiles. However, the international normalized ratio cannot be used to monitor the coagulation profile and currently no antidotes are available. The main adverse effect with all anticoagulants is hemorrhage thus, it is important for physicians to be familiar with their pharmacology, dosing, and toxicity.
The main goals of treatment for DVT include prevention of PE, the PTS, and recurrent thrombosis. Once VTE is suspected, anticoagulation should be started immediately unless there is a contraindication.Different types of anticoagulant can be used including unfractionated heparin (UFH), low-molecular-weight heparin (LMWH), or fondaparinux followed by an oral anticoagulant (vitamin K antagonist [VKA]), Direct thrombin inhibitors.
Dabigatran (direct thrombin inhibitor) and rivaroxaban (factor Xa inhibitor) have been studied extensively and shown to be non-inferior to VKA for treatment of VTE.54Rivaroxaban has been approved by the FDA for use in the prevention of VTE for the patient undergoing total hip or knee replacement surgery. It has also been approved for the treatment of DVT and PE based on clinical trials. In studies comparing rivaroxaban to enoxaparin and a VKA, rivaroxaban was as effective for treatment of VTE. The drug is given orally once daily and is contraindicated in patients with renal insufficiency. The major side effect observed with rivaroxaban is bleeding, similar to other anticoagulants.
Current guidelines recommend 3 months of anticoagulation with a VKA targeting an INR of 2 to 3 for patients with an episode of DVT or PE resulting from a transient cause. Patients who have the antiphospholipid syndrome, who are homozygous for factor V Leiden, or who are doubly heterozygous for factor V Leiden and prothrombin gene mutation should be considered for longer periods of anticoagulation. Long-term (indefinite) anticoagulation is also recommended in patients with malignancy as long as the cancer remains active and in patients who have unexplained recurrent VTE.
Following interaction of the 'contact' factors XI and XII, a cascade of activation occurs to the coagulation protease zymogens. This results in the conversion of fibrinogen to fibrin, the formation of thrombin and finally a platelet-fibrin plug. During healing process, fibrin deposition and removal is regulated by the fibrinolytic system.
Anticoagulants are considered the primary line for preventing and treating thrombosis. New oral anticoagulants such as rivaroxaban, apixaban and dabigatran are expected to replace the older drugs for being easier to use and for having better pharmacodynamic profiles. However, the international normalized ratio cannot be used to monitor the coagulation profile and currently no antidotes are available. The main adverse effect with all anticoagulants is hemorrhage thus, it is important for physicians to be familiar with their pharmacology, dosing, and toxicity.
The main goals of treatment for DVT include prevention of PE, the PTS, and recurrent thrombosis. Once VTE is suspected, anticoagulation should be started immediately unless there is a contraindication.Different types of anticoagulant can be used including unfractionated heparin (UFH), low-molecular-weight heparin (LMWH), or fondaparinux followed by an oral anticoagulant (vitamin K antagonist [VKA]), Direct thrombin inhibitors.
Dabigatran (direct thrombin inhibitor) and rivaroxaban (factor Xa inhibitor) have been studied extensively and shown to be non-inferior to VKA for treatment of VTE.54Rivaroxaban has been approved by the FDA for use in the prevention of VTE for the patient undergoing total hip or knee replacement surgery. It has also been approved for the treatment of DVT and PE based on clinical trials. In studies comparing rivaroxaban to enoxaparin and a VKA, rivaroxaban was as effective for treatment of VTE. The drug is given orally once daily and is contraindicated in patients with renal insufficiency. The major side effect observed with rivaroxaban is bleeding, similar to other anticoagulants.
Current guidelines recommend 3 months of anticoagulation with a VKA targeting an INR of 2 to 3 for patients with an episode of DVT or PE resulting from a transient cause. Patients who have the antiphospholipid syndrome, who are homozygous for factor V Leiden, or who are doubly heterozygous for factor V Leiden and prothrombin gene mutation should be considered for longer periods of anticoagulation. Long-term (indefinite) anticoagulation is also recommended in patients with malignancy as long as the cancer remains active and in patients who have unexplained recurrent VTE.
Other data
| Title | Types of Anticoagulants and Duration Following Venous Thromboembolism | Other Titles | أنواع مضادات تخثر الدم وفترات علاجها ما بعد الجلطات الوريدية | Authors | Yasser Magdy Hamed Mohammed | Issue Date | 2016 |
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