Construction Of A PEG Gel Loaded With Alendronate Sodium Drug Sustained Release System And Study Its Performance

Objective:The four-arm PEG was used for end group modification to obtain a two-component injectable in situ gelled hydrogel drug sustained-release system,loaded with alendronate,then injected into the localized part of the bone where needed to be strengthened,its properties were explored.To provide data on the enhancement of bone focus in osteoporotic fracture sites.Methods:The four-arm PEG end group modification materials 4-PEG-SG and 4-PEG-NH₂ were respectively disposed in an equal amount of aqueous solution,and the hydrogel system was prepared by chemical reaction cross-linking under normal temperature conditions,and the alendronate sodium was loaded.Its reaction was observed by nuclear magnetic resonance?NMR?and the degree of reaction was calculated.In vivo degradation profile of the hydrogel and the drug release behavior of the drug-loaded hydrogel were determined by simulating in vivo conditions.The 4-PEG-NH₂ component in the hydrogel was labeled with a fluorescent molecule,and sterilized and injected into the left femur of the mouse used the small animal fluorescence imaging system combined with MicroCT imaging to observe the hydrogel position,the degradation of the hydrogel and the change of hydrogel fluorescence intensity,as well as the fluorescence of the viscera,and analyze the metabolic pathway in the body.The two components were in vitro molded,sterilized,implanted into the skin of rats,and their histocompatibility was observed and evaluated.Fifty female New Zealand white rabbits were randomly selected and weighed 3.2±0.2kg and were randomly divided into 5 groups.The first group was the sham operation group;the other 4 groups were treated with ovarian extraction to fabricate osteoporosis model.The models were used for 3 months.The bone mineral density?BMD?of the left femur was measured to verify result of the model of osteoporosis.The second group was a blank control group;the third group was a systemic administration group,alendronate was administered by intragastric administration;the fourth group was a blank hydrogel group;and the fifth group was a drug-loaded hydrogel group.Both the blank hydrogel group and the drug-loaded hydrogel group were injected with a hydrogel through a two-pass syringe.Three months later,the left femur of the animal models were measured by dual-energy X-ray absorptiometry.The drug-loaded hydrogel group was simultaneously measured for the right femur,and the bone mineral density was measured by quantitative computed tomography?QCT?.The bone stress was also examined by the three-point bending experiment.Results:The results showed that the degradation curve of the hydrogel was stable and the degradation lasted for 28 days in vitro.The drug burst was not obvious at the initial 24hours,and the subsequent drug release was mild.After 28 days,the PEG hydrogel-loaded drug was completely released in vitro.In vivo fluorescence confirmed that the hydrogel is located near the middle part of the femur,its morphology is aggregated,and the degradation in vivo can reach 84.0±2.2 d.It is mainly metabolized by liver and kidney in the body,and metabolized completely in 105 days.Hydrogel biocompatibility experiments showed that the acute inflammatory reaction occurred on the 3rd day of the tissue surrounding the hydrogel in the surgical area.The pathological sections showed a large amount of inflammatory cell infiltration;after one week,the acute inflammatory reaction decreased,and the pathological sections showed that the inflammatory cells decreased compared with three days;There was no obvious peripheral inflammatory reaction at two weeks,and a small amount of inflammatory cell infiltration was observed in the pathological section.Bone mineral density before and after animal model operation,there is significant different among groups?P<0.05?,it was proved that the osteoporosis model was successful.Three months after treatment of four groups of osteoporosis animal models:the BMD of the whole body administration group and the hydrogel group was significantly higher than that of the blank control group?0.354±0.006g/cm²,0.377±0.008g/cm²,0.330±0.006g/cm²,0.328±0.010 g/cm²,F=89.918,P<0.05?.There was no significant difference in bone mineral density between the blank control group and the blank hydrogel group.The BMD of the left femur in the drug-loaded hydrogel group was significantly higher than that in the whole body administration group,while in the drug-loaded hydrogel group there was significantly higher than that in the right group?0.377±0.008g/cm²,0.347±0.006 g/cm²,t=9.784,P<0.05?.After the experiment,the maximum damage pressure of femur in the blank control group and blank hydrogel group was lower than that in the whole body administration group and the drug-loaded hydrogel group?212.73±8.48N,214.68±8.67N,239.74±10.51N,268.37±6.78N,F=89.654,P<0.05?.The re was no significant difference between the blank control group and the blank hydrogel group in the maximum failure pressure of the femur in the three-point bending experiment.The maximum pressure of the left femur of the hydrogel group was higher than that of the whole body administration group.The maximum damage pressure of the left femurofthehydrogelgroupwashigherthanthatoftherightside?268.37±6.78N,232.16±9.39N,t=9.885,P<0.05?.Conclusion:1.This experiment confirms that the 4-arm PEG hydrogel can be used as a good drug release carrier,and its drug release behavior is confirmed:its in vitro degradation curve is relatively flat,and the in vitro drug release curve shows that the drug sustained release performance is good and does not exist.The obvious burst effect is beneficial to the drug reaching the effective drug concentration in the organism and does not cause the drug concentration be too high.2.Through in vivo experiments in animals,the in vivo degradation and metabolism of PEG hydrogels are revealed:the immunofluorescent molecules are bound by PEG hydrogel,and the small animal live imaging apparatus is used to confirm that the PEG hydrogel which was injected into the body by a two-pass syringe was formed near the middle part of the left femur of the mouse.The degradation time in vivo is 84.0±2.2 d,which is in line with the expected time of drug release.The metabolism in the body is mainly metabolized by liver and kidney,completely metabolized in 105 days and no residue,which shows that biocompatibility is good.The initial acute inflammatory reaction might be caused by the surgical procedures.And the initial foreign body reaction,there is no obvious inflammatory reaction around the hydrogel after two weeks.It indicates that the PEG hydrogel can be used as a drug sustained-release carrier,and its sustained release time is satisfied,and it has high biosafety.3.Through different administration methods,it is proved that the local application of drug-loaded hydrogel could strengthen the local bone mineral density of rabbits,and that the PEG hydrogel drug delivery system loaded with alendronate sodium can strengthen the bone mineral density and strengthen the vulnerable fracture sites of the whole body.4.Through the above experiments,it is proved that PEG hydrogel-loaded anti-osteoporosis drugs have great significance for the prevention of osteoporotic fractures and are expected to be applied to clinical treatment.