Biopharmaceutics classification evaluation for paris saponin VII / 中国天然药物

To study the biopharmaceutics characteristics of paris saponin VII (PSVII). The solubility of PSVII was evaluated by measurement of the equilibrium solubility in different solvents and media. The permeability of PSVII was evaluated by measuring the oil/water partition coefficient (lgP) and determining the apparent permeability coefficient (PC) on a mono-layer Caco-2 cell model. The effects of p-glycoprotein and multidrug resistance related protein 2 on PSVII transport in mono-layer Caco-2 cell model were further investigated. Finally, the small intestinal absorption of PSVII was investigated in rat. In solvents of different pH, the equilibrium solubility of PSVII was quite low, and the dose number of PSVII was larger than 1. The lgP of PSVII was less than 0. The apparent permeability coefficient [PC] of PSVII in mono-layer Caco-2 cell model was less than 14.96 × 10 cm·s, and the efflux ratio of PSVII in mono-layer Caco-2 cell model was less than 1. The transport rate of PSVII in mono-layer Caco-2 cell model was not affected by the inhibitors of p-glycoprotein and multidrug resistance related protein 2. After oral administration, PSVII could be detected in rat intestinal contents, but could not be detected in the small intestinal mucosa. PSVII showed low solubility and permeability, which would result in low oral bioavailability in clinic. PSVII belonged to Class IV compound in biopharmaceutics classification system.

The toxicological mechanisms and detoxification of depleted uranium exposure

Depleted uranium (DU) has been widely applied in industrial and military activities, and is often obtained from producing fuel for nuclear reactors. DU may be released into the environment, polluting air, soil, and water, and is considered to exert both radiological and chemical toxicity. In humans and animals, DU can induce multiple health effects, such as renal tubular necrosis and bone malignancies. This review summarizes the known information on DU's routes of entry, mechanisms of toxicity, and health effects. In addition, we survey the chelating agents used in ameliorating DU toxicity.

Preparation of functional chitosan thermosensitive hydrogel for slow release both rhBMP-2 and chlorhexidine / 生物工程学报

The chitosan thermosensitive hydrogel is liquid at room temperature but gels rapidly when heated to body temperature. This hydrogel are wildly used for cell encapsulation, drug delivery or tissue-engineered scaffolds. The system can sustain the release of macromolecules over a period of several hours to a few days. However, with low-molecular-weight compounds, the release is generally completed within 24 h. To prepare a functional chitosan thermosensitive hydrogel for slow release both broad-spectrum antibiotic chlorhexidine and growth factor recombined human bone morphogenetic protein-2 (rhBMP-2), The beta-cyclodextrin was used to prepare an inclusion complex with chlorhexidine, and then the latter was incorporated into the chitosan thermosensitive hydrogel system. Simultaneously, rhBMP-2 was added into the hydrogel system. By HAAKE viscosity measuring instrument, we contrasted the viscoelastic properties of system with or without objective factors. And the in vitro release kinetics of chlorhexidine and rhBMP-2 was investigated by HPLC (high performance liquid chromatography) and ELISA (enzyme-linked immunosorbent assay) respectively. The results showed that the addition of chlorhexidine/beta-cyclodextrin inclusion complex to the thermosensitive solution did not change the gelling behavior of the thermosensitive system. Further, the in vitro release profiles demonstrated that the release rate of chlorhexidine and rhBMP-2 from hydrogel became slower, controlled delivery over at least 1 month. By first preparing chlorhexidine/beta-cyclodextrin inclusion complex, and then mixing the IC and rhBMP-2 into the chitosan thermosensitive hydrogel, a functional chitosan thermosensitive hydrogel system with ability of slow release both rhBMP-2 and chlorhexidine is successfully made.

Characteristics of drug-release in vitro of different dextran-dexamethasone conjugates / 药学学报

<p><b>AIM</b>To evaluate the effects of molecular weight of dextran on drug-release of conjugate in vitro by screening colon-specific conjugates.</p><p><b>METHODS</b>The conjugates, synthesized with different molecular-weight dextran and dexamethasone, were incubated in the contents of different parts of rat gastrointestinal tract at 37 degrees C. The release of dexamethasone(Dex) and dexamethasonehemisuccinate was determined by HPLC. The mobile phase consisted of 35% acetonitrile and 65% trisodium citrate (50 mmol.L-1, adjusted to pH 4.1 with phosphoric acid).</p><p><b>RESULTS</b>There was no release of dexamethasone or dexamethasonehemisuccinate from conjugates in the stomach contents. The amount of Dex (including dexamethasonehemisuccinate) released from DexD26 in the contents of colon and cecum was shown to be 4.0 times higher than that released in the contents of proximal and distal small intestine while the amount of Dex (including dexamethasonehemisuccinate) released from DexD50 was shown to be 3.6 times higher. The amount of Dex (including dexamethasonehemisuccinate) released from DexD2 in the contents of colon and cecum and from DexD7.6 were 2.0 times and 1.9 times higher, respectively, than that released in contents of proximal and distal small intestine.</p><p><b>CONCLUSION</b>The molecular weight of dextran showed marked effect on drug-release of the conjugate in vitro, and the conjugates with larger molecular-weight dextran have great potential in colon-specific delivery of dexamethasone.</p>