| The determination of molecular weight, thermal stability kinetics ofβ-cyclodextrin polymer (β-CDP) was reported in this paper. Methylene blue, Metformin hydrochloride and Aminophylline were chosen to tabletted withβ-CDP. Furthermore, drug release behavior in vitro and their release mechanism were deeply studied.Theβ-CDP is cross linking withβ-cyclodextrin (β-CD) and epichlorohydrin (EPI) in alkaline environment. Water-soluble, water slightly soluble and water infusibleβ-CDP were obtained by polymerization betweenβ-cyclodextrin and epichlorohydrin. In the determination of molecular weight, the relative molecular weight was gained by gel permeation chromatography (GPC), and intrinsic viscosity was gained by Ubbelohde viscometer in viscosimetry. According to Mark-Houwink equation, the Mark-Houwink constants ofβ-CDP areα=0.4445 and K =0.10678 in 35℃. The relative molecular weights ofβ-CDP were used as direction of react optimization. The molecular weight of optimized water-solubleβ-CDP is 57316.6. Viscosimetry is a reference method for determination of molecular weight ofβ-CDP.In the study of thermal stability, threeβ-CDP were used to calculate E,n,t1/2 and k. Thermal stability parameters of threeβ-CDPs are: E of water-solubleβ-CDP, water slightly solubleβ-CDP and water infusibleβ-CDP is 102.9, 101.6 and 213.2 kJ·mol-1 respectively, n=1, 1, 2. The TG and DSC of water slightly solubleβ-CDP were studied in different heating rate. E =158.2 kJ·mol-1 (Ozawa method), E =160.5 kJ·mol-1 (Kissinger method), A=2.53×1012, k298=4.694×10-16s-1, t1/2298=4.68×107years. The storage period ofβ-CDP was very long in 298K and 373K. The results indicated thatβ-CDP had a good thermal stability. Thermal decomposition reaction mechanism ofβ-CDP belonged to random successive nucleation.The releasing characteristic of drug-β-CDP tablet in vitro was studied. Methylene blue, Metformin hydrochloride and Aminophylline were tabletted with optimizedβ-CDP in different pressure. Release behavior in vitro of three drug-β-CDP tablets was studied by the rotating basket method of dissolution test. The pressure has an effect on Methylene blue-β-CDP tablet.This paper also valuated the results of drug release from drug-β-CDP tablet in vitro with zero-order, first-order, Higuchi and Ritger-pappas mathematical models. Firstly, empirical and half-empirical mathematical model were used to prove that release of drug-β-CDP tablet according to first - order or Higuchi release. The result of Ritger-pappas showed that mechanism of drug release was diffusion and corrosion coexistence, and fick diffusion was mainly release mechanism of drug-β-CDP tablet (release index is 0.490.63). Secondly, diffusion coefficient (D) was calculated by model of"diffusion in sheet"(Crank). The diffusion of drug-β-CDP tablet can be described more intuitionist according to the value of D in long, short and half period, and diffusion coefficient is concentration dependence.
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