| In this study,roxithromycin and theophylline which have a synergistic effect on cough variant asthma were used as the core materials to prepare double drug-loaded microcapsules through spray drying method.SiO2 coated Fe3O4 magnetic nanospheres were prepared by hydrothermal synthesis,then added into the dual drug-loaded microcapsules to increase targeting.In this paper,the structure and properties of the microcapsules were systematically studied.The main contents of this paper are as follows:(1)Methyl cellulose(MC)/sodium alginate(Alg)/methyl cellulose were used as wall material,roxithromycin(ROX)and theophylline(TH)as the core material,the dual drug microcapsule(DDM)was prepared by spray drying method after mechanical stirring and unwrapped drugs on the surface by dialysis.The effects of stirring speed,dialysate time,wall material selection and dosage on the drug loading(DL)of ROX and TH,morphology and particle size were investigated to determine the best preparation conditions.It was found that under the condition of inner MC:1.0 g/50 mLH2O,Alg:4.0 g/180 mLH2O,outer MC:1.0 g/50 mLH2O,ROX:0.6g,TH 0.8 g,stirring speed:100 r/min,the dialysis time:2 h,the DDM has the best morphology,smallest particle size(1.21 ?m)and the highest DL(ROX 6.12%,TH 7.03%).(2)In order to observe the release of DDM in vitro,the regulation of release in 12 h was simulated.The results showed that DDM was sensitive to pH,when the pH value was 1.5 closed to the gastric acid,ROX cumulative release rate was 21.07%,that of TH was 22.31%;when the pH value was 5.6,the cumulative release rate of ROX was 66.96%,that of TH 87.32%;when the pH value was 6.8,the cumulative release rate of ROX was 71.54%,that of TH was 93.14%;when the pH value was 7.4 close to body fluid,the cumulative release amount of ROX was 73.14%,that of TH was 97.52%.The cumulative release of DDM increased gradually with the increase of pH,it was beneficial to the delivery of drugs in the body.Comparison the inhibition zone size of DDM and non encapsulated drug,it was found that DDM has inhibitory effect on Staphylococcus aureus and Escherichia coli,and has stronger bacteriostatic effect on the former.;DDM was better than uncovered medicine for a long period of bacteriostasis,which indicated that microencapsulation has achieved the effect of slow release of drugs.(3)The particle size of magnetic nano-sphere Fe3O4@SiO2 prepared by hydrothermal synthesis method was 730 nm.MC/Alg/MC was used as the wall material to prepare dual drug-loaded magnetic microcapsules(MDDM)by spray drying.By adjusting the amount of magnetic particles,it was found that under the condition of inner MC:1.0 g/50 mL H2O,Alg:4.0 g/180 mL H2O,outer MC:1.0 g/50 mL H2O,ROX:0.6 g,TH:0.8 g,Fe3O4 @SiO2:0.09 g,DL was the highest(ROX 6.44%,TH 7.70%),which was higher than that of DDM.(4)It was proved that MDDM had magnetic response ability by using a vibrating sample magnetometer.It could be used as a magnetic target to target the drug carrier to the site of the lesion.MDDM also had the sensitivity of pH:when the pH value was 1.5,the cumulative release rate of ROX was 24.54%,that of TH was 21.21%;when the pH value was 5.6,the cumulative release rate of ROX was 68.68%,that of TH was 70.63%;when the pH value was 6.8,the cumulative release rate of ROX was 75.85%,that of TH was 77.89%;when the pH value was 7.4,the cumulative release rate of ROX was 83.16%,that of TH was 81.86%.The total cumulative release of MDDM in 12 h was lower than that of DDM,and the addition of magnetic particles lengthened the release time of the drug,indicating its slow release performance was better.Comparison the inhibition zone size of MDDM and non-microencapsulation drug,it was found that MDDM had inhibitory effect on Staphylococcus aureus and Escherichia coli,and had stronger bacteriostatic effect on the former.MDDM was better than the non-microencapsulation medicine for long period of bacteriostasis,indicating that microencapsulation could slow the releasing of the drugs. |
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