These drugs cause the conversion of plasminogen to plasmin causing fibrinolysis leading to dissolution of clots and reperfusion.
Plasmin may also degrade other factors like factor V, VIII and XII.
Note: Clots become more stable as the time passes. So treatment in the beginning is more helpful.
Previously it was mostly used in serious pulmonary embolism and central deep vein thrombosis but now less commonly used because of increased ability of bleeding.
They are also used to remove clots from catheters and shunts.
They are usually administered intravenously.
It may cause hemorrhage.
Sometimes dissolution of clots may lead to increased local thrombi leading to increased platelaet aggregation and thrombosis. This incidence can be reduced buy giving aspirin and heparin along with thrombolytic drugs.
It is contraindicated in pregnancy and in the patients of healing wounds.