Comparative analysis of the activity and content of different streptokinase preparations

Aims The dosage of fibrinolytic agents such as streptokinase must be controlled carefully to maximize therapeutic activity while avoiding adverse effects. Therefore, the integrity and activity of streptokinase products is likely to be clinically relevant. This study was conducted to compare the in vitro characteristics of different streptokinase preparations. Methods and results Sixteen streptokinase preparations (three of which were recombinant) were compared in a chromogenic substrate activity assay by native, and reducing, sodium dodecyl sulphate (SDS)–polyacrylamide gel electrophoresis (PAGE), and N-terminal sequencing. Deficiencies in streptokinase activity were observed in most of the products: only three fulfilled the minimum requirements of the European Pharmacopoeia. These were Icikinase™ (ICI Pharm Ltd, India, only one of two batches tested), Kabikinase® (Pharmacia Upjohn, Sweden), and Streptase® (Aventis Behring GmbH, Germany). The remaining products exhibited activities ranging from 20.8 to 86.6% of the label claim. Differences in composition and purity were demonstrated by both native and reducing SDS-PAGE. N-terminal sequencing of the recombinant preparations showed differences compared with the native protein — indeed, for one product, the 15 N-terminal amino acids bore no resemblance to streptokinase. Conclusion There are wide variations in the activity, purity, and composition of the available streptokinase preparations.