Streptokinase properties

Table 51-3. Comparison of some properties of streptokinase (SK) and tissue plasminogen activator (t-PA) with regard to their use as thrombolytic agentsJ...

Note In fibrinolysis, plasmin, an endopeptidase that is converted from plasminogen by an activator, hydrolyzes fibrin, fibrinogen, factor V, and factor VIII to their inactive products. Hageman factor (factor XII) converts a proactivator to the active activator. Agents such as thrombin, streptokinase, and urokinase therefore enhance the formation of plasmin and hence have fibrin lytic properties. Epsilon-aminocaproic acid inhibits the activator-mediated formation of plasmin and hence may be used as an antidote to streptokinase-urokinase, or in a defibrination syndrome when bleeding from a mucous membrane occurs. 

Been M, de Bono DP, Muir AL, Boulton FE, Fears R, Standring R, Ferres H. Clinical effects and kinetic properties of intravenous APSAC—anisoylated plasminogen-streptokinase activator complex (BRL 26921) in acute myocardial infarction. Int J Cardiol 1986 11(1) 53-61. 

Varidase = 10 000 lU streptokinase and 2500 lU streptodornase. Streptokinase is a protein, an enzyme produced by beta-hemolytic streptococci. It has indirect fibrinolytic properties by binding with plasminogen. It is a fibrin non-specific thrombolytic. 

O. Matsuo, D. Collen, and M. Verstrate. On the fibrinolytic and thrombolytic properties of active site p-anisoylated streptokinase-plasminogen-complex (BRL 26921). Thromb. Res. 24 347 (1981). 

Because it is a foreign protein, streptokinase is associated with significant hypersensitivity reactions. Most people have, at some point in their lives, had a streptococcal infection and, therefore, have developed circulating antistreptococcal antibodies. These antibodies frequently are active against streptokinase as well. The response of the streptokinase to these antibodies can vary widely, from inactivation of the fibrinolytic properties of the protein to rash, fever, and rarely, anaphylaxis. Significant allergic reactions to streptokinase occur in approximately 3% of patients. 

No toxic properties have as yet been ascribed to streptokinase, and little is known of the part it plays in the pathogenesis of streptococcal infections. It is probable, however, that the absence of fibrin from exudates associated with streptococcal infections, such as peritonitis or empyema, is due to the presence of streptokinase, since as shown originally by Tillett, when the specific antibody, antistreptokinase, appears in the blood, fibrin appears in such exudates. Presumably streptokinase is inhibited by the antibody. 

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