Thrombolytic drugs are used to dissolve a preexisting clot or thrombus, often in an acute or emergency situation. Some of thethrombolytic drugs currently used include alteplase, reteplase,streptokinase, tenecteplase, and urokinase.
After I.V. or intracoronary administration, thrombolytic drugs are distributed immediately throughout the circulation, quickly acti-vating plasminogen (a precursor to plasmin, which dissolves fibrin clots).
Alteplase, reteplase, tenecteplase, and urokinase are cleared rap-idly from circulating plasma, primarily by the liver. Streptokinase is removed rapidly from the circulation by antibodies and the reticuloendothelial system (a body system involved in defending against infection and disposing of products of cell breakdown). These agents don’t appear to cross the placental barrier.
Thrombolytic drugs convert plasminogen to plasmin, which lyses (dissolves) thrombi, fibrinogen, and other plasma proteins. (See How alteplase helps restore circulation)
Thrombolytic drugs have a number of uses. They’re used to treat certain thromboembolic disorders (such as acute MI, acute is-chemic stroke, and peripheral artery occlusion) and have also
Thrombolytic drugs are the drugs of choice to break down newly formed thrombi. They seem most effective when administered within 6 hours of the symptoms onset.
In addition, each drug has specific uses.
§ Alteplase is used to treat acute MI, pulmonary embolism, acute ischemic stroke, peripheral artery occlusion, and to restore paten-cy to clotted grafts and I.V. access devices.
§ Streptokinase is used to treat acute MI, pulmonary embolus, and DVT.
§ Reteplase and tenecteplase are used to treat acute MI.
§ Urokinase is used to treat pulmonary embolism and coronary artery thrombosis and for catheter clearance.
· Thrombolytic drugs interact with heparin, oral anticoagulants, antiplatelet drugs, and NSAIDs to increase the patient’s risk of bleeding.
· Aminocaproic acid inhibits streptokinase and can be used to re-verse its fibrinolytic effects. (See Adverse reactions to throm-bolytic drugs.)