Hemostatics

pharmacological substances that promote the arrest of blood flow.

A distinction is made between hemostatics of local action and those that exert a hemostatic effect after absorption. Hemostasis may be produced by cotton and gauze tampons, which block the flow of blood mechanically and facilitate the sealing of the vessels. The local hemostatics include a number of substances prepared from the blood itself. Thrombin, which is obtained from human blood plasma, is used in capillary hemorrhage to wet tampons that are applied to the bleeding surface. The hemostatic sponge (a dry, porous mass that contains thrombin, thrombokinase, and certain salts) is prepared from human or cattle blood plasma. Styptic pencils are used for small skin injuries, abrasions, or scratches. They are made of aluminum and potassium alums, aluminum sulfate, and calcium oxide. Local hemostasis is also produced by substances that cause constriction of the blood vessels (for example, adrenalin added to local anesthetics).

The medicinal preparations that produce a hemostatic effect after entering the body include gelatin and a vitamin K preparation called vikasol. Calcium chloride is widely used, although the concept of its mechanism of action as a thrombokinase activator is insufficiently grounded. Gelatin, a product of the partial hydrolysis of collagen (contained in cartilage and bone), is administered subcutaneously for gastric and intestinal hemorrhages and hemorrhagic diatheses. A hemostatic sponge can also be made from gelatin. Vikasol is prescribed in cases where bleeding is due to a decreased prothrombin content in the blood. Fibrinogen, a component of blood introduced intravenously is also widely used to stop blood flow.

Preparations of certain medicinal plants are also used as hemostatics (the mechanisms of their action have not been eluci-dated). These include infusions and tinctures of the flowers and leaves of Lagochilus mebrians, infusions and liquid extracts of the leaves of the nettle, extracts and infusions of the yarrow, and preparations of the peppery waterwort.

A hemostatic effect is found in certain preparations that lower arterial blood pressure and in preparations that produce contraction of the uterine musculature (preparations of ergot, cotarnine chloride, pituitrin).