| Microemulsion and microemulsion-based gel (MBG) used as drug delivery have attracted more and more attention for recent years. MBG has not only the characteristics of microemulsion, but also the characteristics of gel. Therefore, MBG used as drug delivery could not merely improve the solubility and dispersity of the insoluble drugs, promote the transdermal absorption of drugs, increase the bioavailability of drugs in vivo, but also improve the stability of unstable drugs, and so on. The main research work and results are as follows.The pseudo-ternary-component phase diagrams of microemulsions composed with IPM/CTAB/n-butanol/TX-100/water or IPM/CTAB/n-butanol/TX-100/drug-aqueous-solution, that the drugs were sulfadiazine sodium, metronidazole and4-acetamino phenol, respectively, were drown. Then the gels based on those microemulsions were prepared and MBGs’ conductivity, relative intensity and the reversibility of the gelling process, as well as the soaking case in different solvents were investigated. At the same time the detecting methods of sulfadiazine sodium, metronidazole and4-acetamino phenol were established in physiological saline. Finally, the release case of drugs in MBGs soaking in physiological saline was studied.The results showed that microemulsion composed with IPM/CTAB/n-butanol/TX-100/water formed smoothly when the mass ratio of CTAB and SME (the mixture of n-butanol and TX-100) was1:1and the mass percentage of TX-100in SME was under60%. If the mass percentage of TX-100in SME was under30%, the region of microemulsion with or without drugs was relatively large though drugs could reduced the microemulsion-region. Transparent and homogeneous gels based on above microemulsions were easily obtained when the content of gelatin was controlled in the range of8%-23%. Both conductivity and relative intensity of MBGs without drugs increased as the gelatin content increasing, and the addition of TX-100could reduce the conductivity but increase the conductivity of gels. When containing drugs, MBGs’relative intensity also increased as the gelatin content increasing, but the conductivity showed the bell shaped and they all were smaller than that of MBG without drugs. The gelling process of all kind MBGs was reversible. In water, all kind gels swelled severely and gels without TX-100and drugs collapsed quickly, losing their blocky structure.The qualtity and appearance of MBGs with drugs didn’t change obviously after soaking70min in heptane, cyclohexane and ethyl acetate, respectively, and the qualtity and.volume all reduced in methanol, ethanol, acetone and ether. respectively. In chloroform or CCl4, however, the qualtity and volume of MBGs all increased gradually, but the increase amplitude were all less than that in water. In phosphoric acid buffer solution, with prolonging of soaked time, the quality change of all kind gels varied greatly when pH was3.0or4.0. while the change trend was the same under other pH. In NH4CI-NH3buffer solution, the quality of gels increased gradually while the change ranges were different. In physiological saline, the gels’ quality change was all the bell shaped except that of gel containing metronidazole reduced consistently. Sulfadiazine sodium, metronidazole and4-acetamino phenol all had significant absorption in UV and the standard working curves all showed a good linear relationship so that the concentration of drugs could be detected by UV spectrophotometry. The drugs deliveried in MBG could be released easily in physiological saline although their release speed was different from each other. The concentration of4-acetamino phenol increased rapidly and steadily within former5h and after then increased slowly and reached the maximum around6h where55%paracetamol had been released, after then had little change. The release speed of sulfadiazine sodium was smaller than that of4-acetamino phenol and the release amount was45%after16hours, then the release speed stayed unchanged. The release speed of metronidazole was fastest among three drugs and the release amount reached53%in the first4hours, and then the release speed was slower in5h-24h and the release amount came to62%when MBG was soaked for24hours. A conclusion could be made that majority of the drug deliveried in MBG could release easily in physiological saline although the release speed was different for different drugs and the release speed could be controled under certain conditions. This laid the foundation for application of MBG as drug delivery. |
PDF Full Text Request