Preparation Of Steroidal Drug-Block Copolymer Micelle Intercalated Layered Double Hydroxides And Investigations On Their In Vitro Release Properties

In this thesis, three kinds of steroidal antiinflammatory drugs (Prednisone (PNS), Ethinylestradiol (EE) and Estradiol(E)) were respectively encapsulated in an anionic micelle derived from a biocompatible surfactant PTBEM (poly(tert-butyl acrylate-co-ethyl acrylate-co-methacrylic acid), and the negatively charged micelle was intercalated into galleries of MgAl-LDH by coprecipitation method.Powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and UV-vis spectroscopy indicate a successful intercalation of drug-containing micelle between the LDH layers, and the supramolecular structure models have been proposed. Furthermore, it was found by DSC technique that the thermal stability of drugs has been improved significantly. In addition, in vitro drug release of these composites was carried out in buffer containing phosphate anions. The results show that this drug/PTBEM-LDH can be used in an effective drug release system.Studies on mathematical modeling of drug release show that the system approaches a release mechanism described by the combination of diffusion through the matrix and degradation of the micelle at pH 4.8,pH 6.4 and pH 7.2 (except that PNS exhibits anomalous transport at pH 6.4). It should be noted that the release rate decreases with increasing density of OH group of the drugs and also decreases with decreasing the solubility of the drugs. The concentration of the released drugs (PNS,EE or E) from the composites ranges in 110 mg/L～135mg/L, which is not related to the solubility of the drug itself. The controlled release formulations in this work indicate that this drug-containing micelle intercalated LDH composite has potential application in the field of site-specific drug delivery to the colon (pH 7.2), taking advantage of the long transit time and almost complete release (100%).