What is the mechanism of action for streptokinase in thrombolytic therapy?

Updated: Aug 04, 2021
  • Author: Wanda L Rivera-Bou, MD, FAAEM, FACEP; Chief Editor: Erik D Schraga, MD  more...
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Streptokinase is produced by beta-hemolytic streptococci. By itself, it is not a plasminogen activator, but it binds with free circulating plasminogen (or with plasmin) to form a complex that can convert additional plasminogen to plasmin. Streptokinase activity is not enhanced in the presence of fibrin. Studies using radioactive streptokinase have documented two disappearance rates: a “fast” half-life (~18 minutes) and a “slow” half-life of (~83 minutes). [12]

Because streptokinase is produced from streptococcal bacteria, it often causes febrile reactions and other allergic problems. It can also cause hypotension that appears to be dose-related. Streptokinase usually cannot be administered safely a second time within 6 months, because it is highly antigenic and results in high levels of antistreptococcal antibodies.

Streptokinase is the least expensive fibrinolytic agent, but unfortunately, its antigenicity and its high incidence of untoward reactions limit its usefulness in the clinical setting. Although other fibrinolytic agents are more popular in developed nations such as the United States, streptokinase continues to be widely used in developing nations. [2]

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