Thrombolytic drugs

Thrombolytic drugs

Thrombolytic drugs are used to dissolve a preexisting clot or thrombus, often in an acute or emergency situation. Some of the thrombolytic drugs currently used include alteplase, reteplase, streptokinase, tenecteplase, and urokinase.

Pharmacokinetics

After I.V. or intracoronary administration, thrombolytic drugs are distributed immediately throughout the circulation, quickly activating plasminogen (a precursor to plasmin, which dissolves fibrin clots).

Blood work

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.

Pharmacodynamics

Thrombolytic drugs convert plasminogen to plasmin, which lyses (dissolves) thrombi, fibrinogen, and other plasma proteins.

Pharmacotherapeutics

Thrombolytic drugs have a number of uses. They’re used to treat certain thromboembolic disorders (such as acute MI, acute ischemic stroke, and peripheral artery occlusion) and have also been used to dissolve thrombi in arteriovenous cannulas (used in dialysis) and I.V. catheters to reestablish blood flow.

Now I get it!

How alteplase helps restore circulation

When a thrombus forms in an artery, it obstructs the blood supply, causing ischemia and necrosis. Alteplase can dissolve a thrombus in either the coronary or pulmonary artery, restoring the blood supply to the area beyond the blockage.

Obstructed artery

A thrombus blocks blood flow through the artery, causing distal ischemia.

Inside the thrombus

Alteplase enters the thrombus, which consists of plasminogen bound to fibrin. Alteplase binds to the fibrin-plasminogen complex, converting the inactive plasminogen into active plasmin. This active plasmin digests the fibrin, dissolving the thrombus. As the thrombus dissolves, blood flow resumes.