Xin Song

Preparation of esomeprazole zinc solid dispersion and study on its pharmacokinetics.

Esomeprazole zinc (EZ) is a poorly water-soluble substance. In order to increase its dissolution rate and bioavailability, solid dispersions of esomeprazole zinc (SDEZ) in polyethylene glycol 4000 (PEG4000) with different EZ to PEG4000 ratios were prepared by solvent method. Our studies showed that dissolution rate of EZ were distinctively increased in the solid dispersion system compared to that in pure EZ or physical mixtures. The increase of dissolution rate was obviously related to the ratio of EZ to PEG4000. The solid dispersion system (EZ/PEG4000=1/8, w/w) gave the highest dissolution rate: about 14.7-fold higher than that of the pure EZ. EZ was proved to be in amorphous state in this solid dispersion by using differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) techniques. In vivo administration studies, SDEZ in enteric capsule (SDEZ-EC) has a lower Cmax and a longer Tmax than that of esomeprazole magnesium enteric-coated tablet (Nexium), and the differences of Cmax and Tmax between SDEZ-EC and Nexium are significant. This result suggests SDEZ-EC has a lower absorption rate than Nexium and corresponds with the in vitro dissolution.

Synthesis, characterization, and in vitro and in vivo evaluation of a novel pectin-adriamycin conjugate.

Adriamycin (ADM) has been widely used in the treatment of many types of solid malignant tumor. However, cardiotoxicity, multidrug resistance and a short half-life in vivo are significant problems that limit its clinical application. To resolve these problems, a novel pectin-adriamycin conjugate (PAC) was synthesized by attaching ADM to low-methoxylated pectin via an amide linkage. The ADM content and weight-average molecular weight (Mw) of PAC were greater than 25% (w/w) and 50,360 g/mol, respectively. PAC was highly stable in plasma, but 33.2% of ADM was released from PAC after incubation for 30 h with lysosomes derived from rat liver. PAC was distributed uniformly in the cytoplasm of most A549 cells and accumulated in the nucleus of a few A549 cells after incubation for 30 h. At concentrations equivalent to 0.125-1.000 microg of ADM/mL, PAC did not inhibit the growth of either A594 or B16 cells to the same extent as free ADM or a mixture of ADM and pectin. Interestingly, at all concentrations, PAC inhibited the growth of 2780cp cells in vitro significantly more effectively than ADM or the mixture of ADM and pectin. The anticancer effect of PAC in vivo was evaluated with C57BL/6 mice bearing pulmonary metastases of B16 cells. Compared with ADM and the mixture of ADM and pectin, PAC suppressed tumor growth significantly and prolonged the mean survival time of the B16-inoculated mice. PAC has great potential for development as a tumor targeting polymer-drug.