What is the Difference Between Streptokinase and Urokinase?

Streptokinase and urokinase are both fibrinolytic agents used in the treatment of thrombosis, but they have some differences in their mechanisms of action and other properties. Here are the main differences between the two:

1. Mechanism of action: Unlike urokinase, streptokinase is not an enzyme. In the presence of plasminogen, streptokinase forms a complex with plasminogen (SK-PLG). Plasminogen bound to streptokinase undergoes a molecular rearrangement, which confers on it the property of transforming plasminogen into plasmin. Urokinase, on the other hand, is an enzyme that directly converts plasminogen into plasmin.
2. Efficacy: While both streptokinase and urokinase have equal intracoronary thrombolytic efficacy, patients receiving urokinase have less systemic activity than those receiving streptokinase. In an in vitro model of venous thrombolysis, streptokinase was associated with the slowest rate of clot lysis compared to urokinase.
3. Antibody titers: Urokinase may hold marginal advantages over streptokinase, especially in patients with high preexisting titers of antistreptokinase antibodies.
4. Recombinant tissue plasminogen activator (t-PA): t-PA is a newer fibrinolytic agent that has shown improved efficacy and specificity compared to both streptokinase and urokinase.

In summary, streptokinase and urokinase are both used in the treatment of thrombosis, but they differ in their mechanisms of action, efficacy, and sensitivity to antibody titers. While urokinase may have some advantages over streptokinase, the introduction of t-PA has provided a more effective and specific treatment option for patients with thrombosis.

Comparative Table: Streptokinase vs Urokinase

Here is a table comparing the differences between streptokinase and urokinase:

Both streptokinase and urokinase are fibrinolytic agents, meaning they break down fibrin in blood clots. They are used in the treatment of thrombosis, stroke, and heart attack due to thrombosis. The key difference between the two is their origin: streptokinase is a bacterial protein isolated from beta hemolytic Streptococcus bacteria, while urokinase is a serine protease enzyme isolated from human urine. In terms of clot lysis, streptokinase has a slower rate compared to urokinase.