Thrombolytic (Fibrinolytic) Drugs Thrombolytic drugs are used to
dissolve (lyse) blood clots (thrombi). Blood clots can occur in
any vascular bed; however, when they occur in coronary, cerebral
or pulmonary vessels, they can be immediately life-threatening -
coronary thrombi are the cause of myocardial infarctions,
cerebrovascular thrombi produce strokes, and pulmonary
thromboemboli can lead to respiratory and cardiac failure.
Therefore, it is important to rapidly diagnose and treat blood
clots. Mechanisms of Thrombolysis Thrombolytic drugs dissolve
blood clots by activating plasminogen, which forms a cleaved
product called plasmin. Plasmin is a proteolytic enzyme that is
capable of breaking cross-links between fibrin molecules, which
provide the structural integrity of blood clots. Because of
these actions, thrombolytic drugs are also called "plasminogen
activators" and "fibrinolytic drugs." There are three major
classes of fibrinolytic drugs: tissue plasminogen activator
(tPA), streptokinase (SK), and uroki