Antihemorrhagic

An antihemorrhagic (antihæmorrhagic) agent is a substance that promotes hemostasis (stops bleeding). It may also be known as a hemostatic (also spelled haemostatic) agent. Antihemorrhagic agents used in medicine have various mechanisms of action: Systemic drugs work by inhibiting fibrinolysis or promoting coagulation. Locally acting hemostatic agents work by causing vasoconstriction or promoting platelet aggregation. Hemostatic agents are used during surgical procedures to achieve hemostasis and are categorized as hemostats, sealants and adhesives. They vary based on their mechanism of action, composition, ease of application, adherence to tissue, immunogenicity and cost. These agents permit rapid hemostasis, better visualization of the surgical area, shorter operative times, decreased requirement for transfusions, decreased wound healing time and overall improvement in patient recovery time. There are several classes of antihemorrhagic drugs used in medicine. These include antifibrinolytics, blood coagulation factors, fibrinogen, and vitamin K. Topical hemostatic agents have been gaining popularity for use in emergency bleeding control, especially in military medicine. They are available in three forms—as a granular powder poured on wounds, as a "styptic pencil" or embedded in a dressing. Microfibrillar collagen hemostat (MCH) is a topical agent composed of resorbable microfibrillar collagen. It attracts platelets and allows for the formation of a blood clot when it comes into contact with blood. Unlike the hemostatic clamp, no mechanical action is involved. The surgeon presses the MCH against a bleeding site, and the collagen attracts and helps with the clotting process to eventually stop bleeding. The practical application for MCH is different from that of the hemostatic clamp. Chitosan hemostats are topical agents composed of chitosan and its salts. Chitosan bonds with platelets and red blood cells to form a gel-like clot which seals a bleeding vessel.