Recent developments in ureteral stent: Substrate material, coating polymer and technology, therapeutic function.

The ureteral stent is an effective treatment for clinical ureteral stricture following urological surgery, and the functional coating of the stent could effectively inhibit bacterial colonization and other complications. The present review provides an analysis and description of the materials used in ureteral stents and their coatings. Emphasis is placed on the technological advancements of functional coatings, taking into consideration the characteristics of these materials and the properties of their active substances. Furthermore, recent advances in enhancing the therapeutic efficacy of functional coatings are also reviewed. It is anticipated that this article will serve as a valuable reference providing insights for future research development on new drug-loaded ureteral stents.

In vitro controlled release of sodium ferulate from Compritol 888 ATO-based matrix tablets.

A controlled release matrix formulation for freely water-soluble drug of sodium ferulate (SF) was designed and developed to achieve a 24h release profile. Using Compritol 888 ATO as an inert matrix-forming agent to control the release of SF, formulation granules containing the physical mixtures or solid dispersions were investigated. The matrix tablets for these formulations were prepared by direct compression and their in vitro release tests were carried out. The solid dispersion based tablets were found to be more effective than those compressed from physical mixtures in retarding the release of SF. Drug release from the matrix tablets containing physical mixtures nearly completed within 12h, while that from the solid dispersion formulations lasted for over 24h. Images of the tablet surface and cross-section were characterized by scanning electron microscopy to show the formed pores and channels in the matrices. These might provide the release pathway for the inner embedded drugs. Drug released fast from the matrix tablets with the release-enhancer of lactose. The addition of surfactants was also found to increase the release rate of SF effectively. Moreover, the co-mixing of polyethylene glycol 6000 (PEG 6000) in the waxy matrices played a meaningful role in controlling the drug release for 24h. The drug release from the novel formulation might be attributed to the diffusion-controlled mechanism.

[Relativities between lattice changes and the function of dissolution improvement of poorly soluble drug silymarin based upon PEG 6,000 solid dispersion system].

AIM: To investigate the lattice mechanisms involved in the increased dissolution effect of polyethylene glycol (PEG 6,000) dispersion system on poorly soluble drug silymarin (SILY). METHODS: Fusion method was used to prepare the solid dispersions of SILY with PEG 6,000. Evaluation of the improvement of dissolution was performed with dissolution studies in vitro. X-ray powder diffraction combined with diffraction peak pattern-fitting procedure were applied to quantitatively analyze the changes of lattice parameters. The interaction of SILY and PEG 6,000 was also determined with Fourier transform-infrared (FT-IR) spectroscopy. RESULTS: The dissolution rate of SILY was considerably increased when formulated in solid dispersion of PEG 6,000 as compared to pure SILY. The datum from the X-ray diffraction showed the changes in the lattic spacings and particular diffraction peaks (position and the intensity) of PEG 6,000 and SILY. These could explain the increased rate of SILY released from solid dispersion system. The information of FT-IR spectroscopy showed the absence of well-defined drug-polymer interaction. CONCLUSION: The dissolution improvement of poorly soluble SILY from solid dispersion of PEG 6,000 can be illuminated by the changes of the lattice parameters of PEG 6,000 and the drug.

Strong cellular and humoral immune responses induced by transcutaneous immunization with HBsAg DNA-cationic deformable liposome complex.

Transcutaneous immunization presents a major challenge on account of poor permeability of antigens through the skin barrier. To overcome this limitation, the deformable liposome could be a better method for transcutaneous delivery of these antigens. In this study, hepatitis B surface antigen (HBsAg) plasmid DNA-cationic complex deformable liposome was utilized as a mode for enhanced immunity against the antigen. Deformable liposome was prepared by conventional rotary evaporation method and characterized for various parameters such as vesicles shape and surface morphology, size and size distribution, entrapment efficiency, elasticity and stability. The immune stimulating activity was studied by measuring serum anti-HBsAg titre and cytokines level (interleukin-4 and interferon-gamma) following topical application of liposome in BALB/c mice and results were compared with deformable liposome encapsulated DNA applied topically as well as naked DNA and pure recombinant HBsAg, administered intramuscularly. It was observed that deformable liposome elicited a comparable serum antibody titre and endogenous cytokines levels compared to other vaccinations. The study signifies the potential of deformable liposome as DNA vaccine carriers for effective transcutaneous immunization.

Improvement of the dissolution rate of silymarin by means of solid dispersions.

Solid dispersions of silymarin were prepared by the fusion method with the intention of improving the dissolution properties of silymarin. Polyethylene glycol 6000 (PEG 6000) was used as the inert hydrophilic matrix. The dissolution studies of the solid dispersions were performed in vitro. And the results obtained showed that the dissolution rate of silymarin was considerably improved when formulated in solid dispersions with PEG 6000 as compared to original drug, and the increased dissolution rate might be favorable for further oral absorption.