streptokinase
Summary
Streptokinase is a bacterial enzyme derived from group C β-hemolytic streptococci that acts as a thrombolytic agent by converting plasminogen to plasmin, thereby dissolving blood clots. It was historically used for acute myocardial infarction and pulmonary embolism but has largely been replaced by newer agents due to immunogenicity concerns.
Detail
Streptokinase is a 47-kDa protein produced by Streptococcus pyogenes that functions as an indirect plasminogen activator. Unlike tissue plasminogen activator (tPA), streptokinase forms a 1:1 stoichiometric complex with plasminogen, which then undergoes conformational changes that expose the active site, converting other plasminogen molecules to plasmin. This leads to fibrin degradation and clot dissolution. Clinically, streptokinase was used for thrombolytic therapy in acute ST-elevation myocardial infarction (STEMI), pulmonary embolism, and deep vein thrombosis. However, its bacterial origin makes it highly immunogenic, leading to antibody formation that can cause allergic reactions and neutralize the drug's effectiveness. Contraindications include recent streptococcal infections, previous streptokinase use (within 6-12 months), and hypersensitivity. Major complications include hemorrhage, particularly intracranial bleeding. Due to these limitations and the development of less immunogenic alternatives like alteplase (recombinant tPA), streptokinase use has declined significantly in developed countries, though it remains used in resource-limited settings due to cost considerations.
Sources
- Goodman & Gilman's Pharmacological Basis of Therapeutics
- Harrison's Principles of Internal Medicine
- Katzung's Basic & Clinical Pharmacology
- ACC/AHA Guidelines for STEMI Management
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