we use alteplase to maintain catheter patency. However, I found out an old study with regards of steptokinase use for the same issue, please find it attached with wellness.
Reconstituted Solutions: Streptase reconstituted with 5 mL of saline
(Sodium Chloride Injection USP, 0.9%) or dextrose (Dextrose Injection
USP, 5%) is stable for 24 hours at room temperature (15 to 30°C) and
refrigeration (2 to 4°C).
Hope that helps