Development Of Brucine-loaded Microsphere/Thermally Responsive Hydrogel Combination System For Intra-articular Administration

Intra-articular drug delivery system could directly delivery drug to an affected joint and offer thepossibility of reaching high drug concentrations at the site of action with limited systemic toxicity.However, depending on their chemical structure, some active compounds were rapidly cleared from thejoint, thus requiring numerous injections, which could cause infection or joint disability. To control therelease behavior for prolonged time periods, a novel biologically based drug delivery vehicle was designedfor intra-articular using microsphere/thermally responsive hydrogel combination system in this paper. Andthe brucine was the test drug.Brucine is the active ingredient extracted from Strychnos nux-vomica L. Nux vomica, also known asstrychnine, first recorded in Compendium of Materia Medica, and recorded in each China Pharmacopoeia,is the dried ripe seeds of the Strychnos nux-vomica L. It has effects of activating meridians to stop pain andsubsiding swelling, especially for treating disease like RA and OA.It has been used clinical in traditionalChinese medicine for the treatment of rheumatoid paralysis, numbness, bruises and other diseases afterbeen concocted.Brucine is the active ingredient of nux_vomica, has the effect of analgesic,anti-inflammatory, anti-immune, anti-tumor, anti-arrhythmia, and antagonize the NO inhibitory effect onchondrocyte proliferation. The process of Osteoarthritis （OA） is mainly in the degration of chondrocytes;brucine can effectively promote the proliferation of chondrocytes, hence repair the damage cartilage. Oneof the pathogenesis of Rheumatoid Arthritis （RA） is self-immune, the effect of anti-immune and stop paincan alleviate distress of RA patients.The system was constructed by disperse the brucine microspheres which was prepared by using aspray-drying method in a thermally responsive biopolymer hydrogel contained of chitosan-glycerol-borax.The hydrogel can block the burst release of microspheres, and the microspheres were incorporated inhydrogel as drug depot.The duplexing release system could effectively prolong the release behavior in thejoint cavity, increase the efficiency of brucine for a extended period of time.The microspheres were prepared by Switzerland Buchi B290spray-drying apparatus.Firstlydetermines the craft factors of outlet temperature, Q-flow, pump speed. The outlet temperature was120℃,Q-flow was40m³/h, Pump speed of20%·min^-1. Then, investigate the influence of type of chitosan,chitosan concerntration, glutaral ratio, ratio of brucine to chitosan on the entrapment efficiency （EE） and in vitro drug release behavior of brucine micropheres. By single-factor test chose three factors, by orthogonaldesign optimization prescription, selected the best prescription for Chitosan0.75%, glutaral ratio of1:15,the ratio of brucine to chitosan is1:5.The Drug loading（DL%） was15.57%±0.07%and Entrapmentefficiency（EE%） was98.61%±0.42%.The brucine microspheres were characterized by SEM, XRD, and FTIR, spherical as evidenced by thescanning electron microscopy （SEM） photographs. With an average size of2.45μm, in range of0.9–4.5μm,agree with normal distribution. Fourier transforms infrared （FT-IR） spectroscopy and X-ray diffraction（XRD） revealed the absence of drug-polymer interaction and amorphous nature of entrapped drug.The thermosensitive converse hydrogel was constructed using chitosan-glycerol-borax as matrix,taking gelation time and gelation condition as index, investigate the influence of concerntraion of chitosan,ratio of chitosan to glycerol,pH on physical properties of hydrogel. The best prescription was CS2%, CS:glycerol10:1, pH6.7.Taking tube method, investigated the in vitro drug release of brucine microsphere（BM）, brucinehydrogel（BH）,brucine microsphere hydrogel（BMH）, the release behavior of each preparation was evaluatedby first-order, Higuchi, Hixon-Crowell; Peppa’s and Double exponential biphasic kinetics equation. Threepreparations were all fit Double exponential biphasic kinetics equation.Investigated the biocompatibility of BM, BH, BMH to rats’ synovium, results showed that thepreparations appeared to be generally biocompatible with synovium and hence it might be suitable for thedevelopment of treatment strategies for arthritis diseases.In vivo FX imaging technology was employed to determine the release behavior of preparation in vivo.Encapsulated infrared dye LF NIRD-15into microspheres instead of brucine; visually investigate theretention time of drugs in the joint cavity. The release behavior of microsphere and microsphere hydrogelwere investigated, results showed that by dispersing the microspheres into hydrogel, the burst wereobviously retarded, and could delivery drug for7days above.The pharmacokinetics of BMH in rats were preliminarily studied.Firstly using RP-HPLC establish themethod to analyse brucine in vivo.Rats were administrated with BS, BM, BMH respectively, using3p97software calculated the pharmacokinetic parameters, results indicated that BMH has a MRT1.93times ofBM,3.38times of BS, could meet the request of design of our topic. In conclusion, the system significantly prolonged the release of brucine in cavity for more than7days,decrease the frequency of injection and improve the compliance of patients, hence it might be suitable forthe development of treatment strategies for rheumatic diseases.