Fibrinolytic

Fibrinolytic refers to the process of fibrinolysis, the enzymatic breakdown of fibrin in blood clots. In medicine, fibrinolytic agents are drugs that promote this process to dissolve pathological clots.

Fibrinolysis is driven by plasmin, an enzyme produced from plasminogen. Plasminogen is activated by plasminogen activators, including tissue plasminogen activator (tPA), urokinase, and streptokinase. Plasmin cleaves fibrin, leading to clot dissolution. The activity is regulated by inhibitors such as PAI-1, PAI-2 and alpha-2-antiplasmin to prevent excessive breakdown.

Clinically, fibrinolytics are used to treat thrombotic conditions such as acute myocardial infarction, pulmonary embolism, and ischemic stroke when rapid clot dissolution is indicated and when mechanical recanalization is unavailable or delayed. They can be given systemically or, in some cases, directly at the clot site via catheter.

Common fibrinolytic agents include tissue plasminogen activator derivatives such as alteplase, tenecteplase, and reteplase; streptokinase; and urokinase. tPA variants are more fibrin-specific, aiming to limit systemic plasmin activity.

Risks include major bleeding and intracranial hemorrhage. Contraindications include active internal bleeding, recent intracranial or intraspinal surgery, known intracranial pathology, severe uncontrolled hypertension, and recent stroke or major head injury, among others. Because of bleeding risk, patients are carefully selected and monitored during therapy.

If bleeding occurs, therapy is stopped and antifibrinolytics such as tranexamic acid or aminocaproic acid may be used in some settings to slow or reverse fibrinolysis.