Hemostatics are medications used to induce hemostasis, which is a physiological process that results in clot formation to prevent or stop a hemorrhage.
Primary hemostasis first starts when platelets are activated and aggregate to form a platelet plug at the site of an injured blood vessel.
Next, secondary hemostasis starts with the coagulation cascade, when clotting factors become consecutively activated to ultimately activate prothrombin into thrombin.
The activated thrombin then cleaves fibrinogen into fibrin, which binds with other fibrin proteins to form a fibrin mesh that reinforces the platelet plug.
Now, when the tissue has healed, the endothelial cells produce an enzyme called tissue plasminogen activator, or tPA, which in turn converts plasminogen into its active form plasmin.
Plasmin then acts as a protease by cutting fibrin into smaller pieces, called fibrinolysis, and ultimately dissolving the clot.
Now, the most commonly used hemostatics include antifibrinolytics, such as aminocaproic acid and tranexamic acid, and vitamin K analogues like phytonadione, which can be administered orally, intravenously, intramuscularly, or subcutaneously; as well as topical hemostatic agents, such as gelatin, microfibrillar collagen, bovine thrombin, and human fibrin sealant, which are applied topically.
Let’s first focus on antifibrinolytics, which work by inhibiting the conversion of plasminogen to plasmin, which ultimately prevents fibrinolysis.