Thrombolytics

Thrombolytics, also called fibrinolytics, are medications that break up blood clots formed during hemostasis, where hemo means blood, and stasis means to halt or stop.

Hemostasis is divided into primary hemostasis, which involves the formation of a platelet plug at the site of an injured blood vessel, and secondary hemostasis, which involves multiple coagulation factors working together to form a fibrin mesh to stabilize the platelet plug.

Together, these two processes create a blood clot which stops the bleeding.

Sometimes blood clots could cause problems, like when they form in a coronary artery to cause a heart attack, or when they break off and travel to the brain and cause a stroke.

In these instances we can use thrombolytics to break up the clot and restore blood flow.

Thrombolytic medications were actually derived physiologically--from what is known as the fibrinolytic system.

Approximately two days after an injury occurs to a blood vessel and the blood clot forms, it’s time for the body to dissolve the blood clot through a process called fibrinolysis, which is the gradual degradation of the fibrin mesh.

To do this, a circulating protein produced by the liver called plasminogen, gets converted by an enzyme called tissue plasminogen activator, or tPA, into its active form called plasmin.

Normally, healthy endothelial cells release only tiny amounts of tPA, but when they’re exposed to coagulation factors produced during 2ndary hemostasis, Factor Xa and thrombin in particular, they start making lots of tPA.

But it’s important that plasmin activity doesn’t get out of hand, either.

So the endothelial cells also release plasminogen activator inhibitor 1 and antiplasmin which are proteins that bind and sequester tPA and plasmin respectively.

It’s all about always reaching that zen balance of coagulation and anticoagulation.