Summary
A new method of determining streptokinase concentrations on a quantitative basis in
the plasma of patients undergoing streptokinase infusion is demonstrated. The principle
of this method is based on the clot lysis time recorded by the thrombo-elastograph.
The test clot constituents were bovine fibrin, bovine plasminogen, human euglobulin,
EDTA, human plasma (with unknown streptokinase quantity) and thrombin. As plasminogen
(euglobulin) and fibrinogen were present in the test coagulum in rather high concentrations
(fixed excess) no interference with changing plasminogen and fibrinogen levels of
the patient’s plasma was observed. Further, due to high EDTA concentrations, no interaction
with platelet functions and coagulation factors took place. The standard error of
measuring 5 u of streptokinase in one ml of human plasma was determined at s = ±0.47
u/ml.
Eleven patients undergoing fibrinolytic treatment with streptokinase were monitored
by streptokinase determination in the plasma. In this group of patients, streptokinase
concentration values varying between 15 and 0.5 units/ml plasma were measured. One
striking feature was the continuous decrease in streptokinase concentration in the
plasma, in spite of unchanged streptokinase infusion rates. This observation was consistent
in regimens with both large (100,000 u/h) and small (30,000 u/h) streptokinase infusion
rates. No explanation is available for this observation up to now. A rise in circulating
anti-streptokinase contents was precluded. Possibly, an accelerated streptokinase
metabolism rate in the course of long-term streptokinase administration may be involved.
