Thrombin (Bovine Origin)
Action and Clinical Uses:
Thrombostat is a protein substance produced through a conversion reaction in which prothrombin of bovine origin is activated by tissue thromboplastin in the presence of calcium chloride. Thrombin requires no intermediate physiological agent for its action. It clots the fibrinogen of the blood directly. Failure to clot blood occurs in the rare case where the primary clotting defect is the absence of fibrinogen itself. The speed with which thrombin clots blood is dependent upon its concentration. For example, the contents of a 5 000 unit vial dissolved in 5 mL of saline diluent is capable of clotting an equal volume of blood in less than a second, or 1 000 mL in less than a minute.
Indications And Clinical Uses:
As an aid in hemostasis wherever oozing blood from capillaries and small venules is accessible.
In various types of surgery, solutions of thrombin may be used in conjunction with absorbable gelatin sponge for hemostasis.
In persons known to be sensitive to any of its components and/or to material of bovine origin.:
Warnings in Clinical States:
The use of topical bovine thrombin preparations has occasionally been associated with abnormalities in hemostasis ranging from asymptomatic alterations in laboratory determinations such as prothrombin time (PT), and partial thromboplastin time (PTT) to mild to severe bleeding or thrombosis which rarely have been fatal. These hemostatic effects appear to be related to the formation of antibodies against bovine thrombin and/or factor V which in some cases may cross react with human factor V potentially resulting in factor V deficiency. Repeated clinical applications of topical bovine thrombin increase the likelihood that antibodies against thrombin and/or factor V may be formed. Consultation with an expert in coagulation disorders is recommended if a patient exhibits abnormal coagulation laboratory values, abnormal bleeding, or abnormal thrombosis following the use of topical thrombin. Any interventions should consider the immunologic basis of this condition. Patients with antibodies to bovine thrombin preparations should not be re-exposed to these products.
Because of its action in the clotting mechanism, thrombin must not be injected or otherwise allowed to enter large blood vessels. Extensive intravascular clotting and even death may result. Thrombin is an antigenic substance and has caused sensitivity and allergic reactions, including anaphylaxis.
General: Consult the absorbable gelatin sponge product labeling for complete information for use prior to utilizing the thrombin-saturated sponge procedure.
Pregnancy and Lactation: Animal reproduction studies have not been conducted with thrombin. It is also not known whether thrombin can cause fetal harm when used in nursing mothers or pregnant women, or if it can affect reproduction capacity. There are no adequate and well-controlled studies in pregnant women or nursing mothers; therefore, thrombin should not be given to these patients unless the benefits to the mother clearly outweigh the potential risks to the fetus or nursing child.
Children: Safety and effectiveness in pediatric patients have not been established.
Allergic reactions may be encountered in persons known to be sensitive to bovine materials.
An allergic type reaction following the use of thrombin for treatment of epistaxis has been reported. Febrile reactions have also been observed following the use of thrombin in certain surgical procedures, but no cause-effect relationship has been established.
Anaphylaxis (see Warnings).
Hematologic (see Warnings).
Dosage And Administration:
Solutions of thrombin may be prepared in sterile distilled water or isotonic saline. The intended use determines the strength of the solution to prepare. For general use in plastic surgery, dental extractions, skin grafting, neurosurgery, etc., solutions containing approximately 100 u/mL are frequently used. For this, an appropriate dilution of Thrombostat should be prepared to yield a concentration of 100 units/mL. Where bleeding is profuse, as from cut surfaces of liver and spleen, concentrations as high as 1 000 to 2 000 u/mL may be required. Intermediate strengths to suit the needs of the case may be prepared by selecting the proper strength package and dissolving the contents in an appropriate volume of diluent. In many situations, it may be advantageous to use thrombin in dry form on oozing surfaces.
Caution: Solutions should be used immediately upon reconstitution. If necessary, refrigerate the solution and use within 3 hours of reconstitution.
The following techniques are suggested for topical application:
1. The recipient surface should be sponged (not wiped) free of blood before thrombin is applied.
2. A spray may be used or the surface may be flooded using a sterile syringe and small gauge needle. The most effective hemostasis results when the thrombin mixes freely with the blood as soon as it reaches the surface.
3. In instances where thrombin in dry form is needed, the vial is opened by removing the metal ring by flipping up the plastic cap and tearing counterclockwise. The rubber-diaphragm cap may be easily removed and the dried thrombin is then broken up into a powder by means of a sterile glass rod or other suitable sterile instrument.
4. Sponging of treated surfaces should be avoided in order that the clot remain securely in place.
Thrombostat may be used in conjunction with Absorbable Gelatin Sponge, USP as follows:
1. Prepare thrombin solution of the desired strength.
2. Immerse sponge strips of the desired size in the thrombin solution. Knead the sponge strips vigorously with moistened gloved fingers to remove trapped air, thereby facilitating saturation of the sponge.
3. Apply saturated sponge to bleeding area. Hold in place for 10 to 15 seconds with a pledget of cotton or a small gauze sponge.
Availability And Storage:
Thrombostat is supplied as a sterile powder that has been freeze-dried in the final container. It is prepared under rigid assay control against US Standard Thrombin. Vials containing 5 000 units of Thrombostat (nonmedicinal ingredients: amino acetic acid, calcium chloride and sodium chloride) and vials containing 10 000 units of Thrombostat (nonmedicinal ingredients: amino acetic acid, calcium chloride and sodium chloride). Store at controlled room temperature (15 to 30°C).
THROMBOSTAT Parke-Davis Thrombin (Bovine Origin) Topical Hemostatic