Development and characterization of multivesicular liposomes bearing serratiopeptidase for sustained delivery

Serratiopeptidase exhibits proteolytic activity and is used in the therapy of inflammation. It is rapidly degraded under harsh gastric environments; hence it is conventionally delivered as an enteric-coated product. There is severe loss of enzyme activity during the compression of tablets. Therefore, it is pivoted to develop a delivery system, which could sustain therapeutic blood and tissue level of drug for an extended period of time and avoids frequent dosing and loss of its proteolytic activity. The present study aimed to prepare and characterize serratiopeptidase bearing multivesicular liposomes for sustained delivery of serratiopeptidase. Multivesicular liposomes (MVLs) bearing serratiopeptidase were prepared using the double emulsification technique using amphipathic lipid, cholesterol, neutral oil and negatively charged lipid and characterized for their shape, size, drug entrapment and in vitro drug release. In vivo performance of multivesicular liposomes bearing serratiopeptidase was evaluated by assessing anti-inflammatory activity using the carrageenan-induced rat paw edema volume method and the cotton pellet granuloma method. The results thus obtained were compared with those of conventional drug solution and conventional liposomes containing serratiopeptidase in equal amounts. Optimized formulation parameters resulted in homogenous population of multivesicular liposomes having high encapsulation efficiency and spherical vesicle morphology. Vesicle size was found to be in the range 4.30 ± 0.25 μm to 19.61 ± 0.42 μm. The MVLs were found to be sensitive to osmotic pressure, responding by shrinking when the osmolarity of the medium was increased. Drug encapsulation was observed at 24.6 ± 0.99% in the case of conventional liposomes while it increases to 86.5 ± 4.24% in MLVs (SP MVL-S-b). The in vitro release reveals that conventional liposomal formulation releases more than 80% drug within 48 h while MVL formulations release the same amount of drug in 120 h. In vivo data reveal that reduction in inflamed paw volume with the MVLs formulation was not rapid but effect was maintained for prolonged period and even after 6 h there was 68 ± 1.26% reduction in inflamed paw volume. MVLs formulation shows 66.48 ± 1.82% inhibition in weight of granuloma in three days. MVL formulation showed more sustained and prolonged anti-inflammatory effect as compared to conventional drug and conventional liposomal formulation.