Research Of Diclofenac Sodium Silk Fibroin-chitosan Sustained-release Microsphere

Objective: A sustained-release microsphere was prepared by using Silk Fibroin(SF) and Chitosan(CS)as carriers and Diclofenac Sodium(DS) as model medicine,based on porous structure of SF and excellent plasticity of CS. DS's acting time was prolonged while side effects were reduced by preparing the microsphere with SF and DS.Methods: (1) The DS detection method in vitro was established by High Performance Liquid Chromatogram (HPLC) , and physicochemical properties such as solubility, hydrolytic substance, oil/water partition coefficient, etc. were determined. (2)The extraction process of SF was obtained by comparing the rate of production. (3) DS-SF/CS-MS were prepared with an emulsion crosslinking technique. The orthogonal design was used to optimize the technology of preparation of drug-loaded microspheres.(4) The surface characteristic of DS-SF/CS-MS was determined by scanning electronic microscope(SEM),the modified alkalimetry differential scanning calorimetry (DSC), X-ray diffraction, etc.Dynamic dialysis system was adopted to study the release dynamics in vitro. (5) Pharmacokinetic characteristic of DS-SF/CS-MS was estimated through intragastric administration.Results: (1) DS was determined by HPLC as follows: ten microliter sample was injected into a chromatograph (Shimadzu LC-10AT, Japan) equipped with a UV detector (Shimadzu SPD-M10A) and reversed phase column (Hypersil ODS2, 4.6×250mm, Elite, Dalian, China). The mobile phase was a mixture of methanol: 1.5% acetic acid=78:22, and the flow rate was 1.01.0ml·min-1 with the wavelength of 276nm at 30℃. The solubility of DS was enhanced along with the increasing pH of dissolution medium .(2)The raw silk fibers were processed in 0.5 wt% Na2CO3 solution to remove sericin (degumming) and dried at room temperature.The degummed fibroin was dissolved in the ternary solvent, CaCl2–ethanol–water.(3)Entrapment and loading capacity were taken as indexes, and the optimal condition was: The concentrations of emulsifier(Span-80),CS,acetic acid, glutaric dialdehyde were 0.010g/ml,4.5%,4%,0.025g/ml respectively. On this condition, the entrapment of 55.46% and the loading capacity of 10.78% were performed. (4)SEM graph shows the microparticles were sphere and distinct.The average diameter was (26.54±1.39)μm. In DSC,X-ray diffraction graph, the diagnostic absorption peak of DS,SF and CS vanished or shifted.The release of diclofenac sodium followed Higuchi's equation in vitro and was sustained for 200h. (4) The plasma concentration versus time curve was coincident with one compartment model.MRT and T1/2 of DS-SF/CS-MS was prolonged and relative bioavailability was 140.0%.Conclusions: SF/CS-MS was a potential novel sustained-release carrier material with low toxicity because of its excellent performance.