Subconjunctivally injected, liposome-encapsulated streptokinase enhances the absorption rate of subconjunctival hemorrhages in rabbits

Liposome-encapsulated streptokinase (SK) was prepared with distearoylphosphatidylethanolamine-N-[methoxy(polyethyleneglycol)-2000] (DSPE-PEG2000). In vitro release assay demonstrated over 81% of SK was released from liposomes at 48 h, and the effect of its subconjunctival injection on the absorption rate of induced subconjunctival hemorrhage (SH) in rabbits was evaluated. After 8 h of SH induction, eyes were randomly assigned to one of four subconjunctival injection groups (10 eyes each): group A: the free form of SK (1000 IU/mL); group B: liposome-encapsulated SK (1000 IU/mL); group C: 0.1 mL of liposomes; and group D: no injection. SHs were photographed at 8, 24, 48, 72, and 120 h after SH induction and their sizes were compared. Size decrease of the SH was faster in groups A and B than in groups C and D. Group B displayed significantly different absorption rates than group A at 24 and 48 h and with groups C and D at 24, 48, and 72 h, with the shortest mean elapsed time among all groups. The ocular absorption of SK was lower after the injection of the liposome-encapsulated SK than the free form. These results demonstrated that subconjunctival injection of liposome-encapsulated SK enhances the rate of SH absorption, especially in the early phases.