Drying of a plasmid containing formulation: chitosan as a protecting agent

BACKGROUND

The purpose of the study. Along with research on development of more efficient gene delivery systems, it is necessary to search on stabilization processes to extend their active life span. Chitosan is a nontoxic, biocompatible and available gene delivery carrier. The aim of this study was to assess the ability of this polymer to preserve transfection efficiency during spray-drying and a modified freeze-drying process in the presence of commonly used excipients.

METHOD

Molecular weight of chitosan was reduced by a chemical reaction and achieved low molecular weight chitosan (LMWC) was complexed with pDNA. Obtained nanocomplex suspensions were diluted by solutions of lactose and leucine, and these formulations were spray dried or freeze dried using a modified technique. Size, polydispersity index, zeta potential, intensity of supercoiled DNA band on gel electrophoresis, and transfection efficiency of reconstituted nanocomplexes were compared with freshly prepared ones.

RESULTS AND MAJOR CONCLUSION

Size distribution profiles of both freeze dried, and 13 out of 16 spray-dried nanocomplexes remained identical to freshly prepared ones. LMWC protected up to 100% of supercoiled structure of pDNA in both processes, although DNA degradation was higher in spray-drying of the nanocomplexes prepared with low N/P ratios. Both techniques preserved transfection efficiency similarly even in lower N/P ratios, where supercoiled DNA content of spray dried formulations was lower than freeze-dried ones. Leucine did not show a significant effect on properties of the processed nanocomplexes. It can be concluded that LMWC can protect DNA structure and transfection efficiency in both processes even in the presence of leucine.

Drying of a plasmid containing formulation: chitosan as a protecting agent

Background

Along with research on development of more efficient gene delivery systems, it is necessary to search on stabilization processes to extend their active life span. Chitosan is a nontoxic, biocompatible and available gene delivery carrier. The aim of this study was to assess the ability of this polymer to preserve transfection efficiency during spray-drying and a modified freeze-drying process in the presence of commonly used excipients.

Methods

Molecular weight of chitosan was reduced by a chemical reaction and achieved low molecular weight chitosan (LMWC) was complexed with pDNA. Obtained nanocomplex suspensions were diluted by solutions of lactose and leucine, and these formulations were spray dried or freeze dried using a modified technique. Size, polydispersity index, zeta potential, intensity of supercoiled DNA band on gel electrophoresis, and transfection efficiency of reconstituted nanocomplexes were compared with freshly prepared ones.

Results and conclusion

Size distribution profiles of both freeze dried, and 13 out of 16 spray-dried nanocomplexes remained identical to freshly prepared ones. LMWC protected up to 100% of supercoiled structure of pDNA in both processes, although DNA degradation was higher in spray-drying of the nanocomplexes prepared with low N/P ratios. Both techniques preserved transfection efficiency similarly even in lower N/P ratios, where supercoiled DNA content of spray dried formulations was lower than freeze-dried ones. Leucine did not show a significant effect on properties of the processed nanocomplexes. It can be concluded that LMWC can protect DNA structure and transfection efficiency in both processes even in the presence of leucine.

Pharmacokinetic study of niosome-loaded insulin in diabetic rats

BACKGROUND AND THE PURPOSE OF THE STUDY

Encapsulation of human insulin in lipid vesicular systems such as niosomes was sought as a route to protect this protein against proteolytic enzymes and to improve its oral bioavailability. The purpose of this study was to assess the effect of insulin encapsulation in niosomes on oral bioavailability in diabetic rats.

METHODS

Recombinant human insulin was entrapped in multilamellar niosomes composed of polyoxyethylene alkyl ether surfactants (Brij 52 and Brij 92) or sorbitan monostearate (Span 60) and cholesterol. The amount of insulin released in simulated intestinal fluid (SIF) and simulated gastric fluid (SGF) were measured at 37°C. The protection of entrapped insulin against pepsin, α-chymotrypsin and trypsin were evaluated in comparison with free insulin solution. Diabetes was induced by IP injection of streptozotocin (65 mg/kg) in male wistar rats and effects of orally administered niosomes and subcutaneously injected insulin on hypoglycemia and elevation of insulin levels in serum were compared.

RESULTS AND CONCLUSION

The extent and rate of insulin release from Brij 92 and Span 60 vesicles were lower than that of Brij 52 niosomes (P<0.05). Vesicles protected insulin in comparison with free insulin solution against proteolytic enzymes (P<0.05) significantly. Animals treated with oral niosome-encapsulated insulin (100 IU/kg) showed decreased levels of blood glucose and elevated serum insulin, which in the case of Brij 92 niosomes, hypoglycemic effect was significant (P<0.05). Niosomes were also stable in solubilizing bile salt solutions and could effectively prolong the release of insulin in both SGF and SIF. Results of this study showed that niosomes may be utilized as oral carriers of insulin; however, to increase bioavailability of insulin, further studies on the protease inhibitor co-encapsulation in niosomal formulations might be helpful.