Determination of rebamipide in human plasma by a validated liquid chromatography-tandem mass spectrometry: Application in pharmacokinetics research.

A new method for the determination of rebamipide in human heparin sodium plasma by LC-MS was established and its methodology was validated. In this method, protein precipitation method was used to pretreat the samples and the rebamipide-d4 isotope of rebamipide was used as the internal standard. In the multi reaction monitoring mode, the electrospray ion source was used as the ionization technolog and LC-MS was used for detection and analysis. The liquid chromatographic conditions were: 00B-4605-AN (Kinetex® XB-C18 100A 50mm × 2.1mm, 5µm); mobile phase A: 0.1% FA and 1 mM NH4FA aqueous solution, mobile phase B: 0.1% FA and 1mM NH4FA 90% ACN solution, flow rate: 0.300mL/min, injection volume: 10uL, column temperature: 30oC, collection time: 3 min, injector temperature control: 5oC. The retention time of rebamipide and rebamipide-d4 were 1.32min and 1.31min, respectively. The lower limit of quantification was 1ng/mL and the calibration map of rebamipide in the concentration range of 1 to 800ng/mL was linear (R2 >0.990, n=11). The CV% values of the inter and intra batch precision of the method were both less than 15.0%. This method has been successfully applied to pharmacokinetic studies to evaluate the main pharmacokinetic parameters of rebamipide.

[Effects of paclitaxel loaded-drug micelles on cell proliferation and apoptosis of human lung cancer A549 cells].

This study was conducted to investigate the paclitaxel loaded by hydrazone bonds in poly(ethylene glycol)-poly(caprolactone) micelles (mPEG-PCL-PTX) on proliferation and apoptosis of human lung cancer A549 cells and its possible mechanisms of anti-tumor activity. The cell proliferation was measured with MTT assay. Flow cytometry were used to analyze the cell cycle. The cell apoptosis was analyzed using Hoechst/P staining. The expression levels of apoptotic genes expression in the mitochondrial apoptosis pathway were detected by RT-PCR and Western blotting, respectively. The mPEG-PCL-PTX could inhibit the proliferation of A549 cells and promote the apoptosis. The Bax, caspase-3 protein expression were increased while Bcl-2 protein expression was decreased in A549 cells. Results showed that the polymer containing hydrazone bond is non-toxic in vitro, the mPEG-PCL-PTX micelles can inhibit the proliferation and induce the apoptosis of A549 cells. Key words: paclitaxel; micelle; A549 cell; proliferation; cell cycle; apoptosis

Validation of an Ion-Pair Reverse Phase High-Performance Liquid Chromatography Method for the Detection of Major Components and Related Substances in Diquafosol Sodium Eye Drops.

A simple, feasible, isocratic elution, and stable reversed-phase high performance liquid chromatography method was established and verified. The chromatographic conditions are as follows: EF-C18H, 4.6 × 250 mm, 5 µm column; column temperature 30 °C; for the mobile phase 27.2 g of KH2PO4 and 8.5 g of tetrabutylammonium hydrogen sulfate were taken, 2500 mL of water was added to dissolve, and the pH was adjusted to 6.7 with phosphoric acid:methanol solution with a ratio of 84:16 (V:V). The flow rate was 1.0 mL/min; the injection volume was 10 µL; and the wavelength was 262 nm. According to the current ICH guidelines, the developed method was verified, and the system suitability, specificity, LOD, LOQ, linearity, range, accuracy, repeatability, durability, and solution stability of the proposed method were verified. The validation results demonstrated that the LOQ for the method was 0.05% and the LOD was 0.02%. The content was detected within the concentration range of 300 to 900 µg/mL. The relationship between concentration and measurement was linear, with an r2 of >0.999. The concentration of impurities ranged from 0.3 to 4.5 µg/mL. A good linear correlation was observed within the range of g/mL, with a coefficient of determination r2 greater than 0.999. The accuracy and repeatability met the specified criteria.

PEGylated Solanesol for Oral Delivery of Coenzyme Q10.

Coenzyme Q10 (CoQ10) is widely used in preventive or curative treatment of cardiovascular diseases. However, CoQ10 exhibits an extremely low solubility in aqueous medium as well as a poor oral bioavailability. Therefore, solanesyl poly(ethylene glycol) succinate (SPGS) and CoQ10 were formulated as CoQ10-SPGS micelles with a high content of CoQ10 to improve the bioavailability of CoQ10 in rat. Findings indicate that, in the CoQ10-SPGS micelles, SPGS is self-assembled into stable nanosized micelles with a CoQ10 loading capacity of more than 39%. The CoQ10-SPGS micelles exhibit an enhanced photostability upon exposure to simulated sunlight. In vivo experiments demonstrate that, as compared to that of the coarse suspensions of CoQ10, there was three-fold enhancement of oral bioavailability for CoQ10-loaded SPGS micelles depending on varying molecular weight of SPGS. In the encapsulation of CoQ10 by SPGS micelles, the self-assembled nanocarriers with strong muco-adhesive properties lead to increases in the solubility and oral absorption of lipophilic CoQ10 nanoparticles.

mPEGylated solanesol micelles as redox-responsive nanocarriers with synergistic anticancer effect.

We prepared an amphiphilic redox-responsive conjugate based on mPEGylated solanesol, solanesyl poly(ethylene glycol) dithiodipropionate (SPDP), along with its inert counterpart solanesyl poly(ethylene glycol) succinate (SPGS), which self-assembled in aqueous solution to form redox-responsive micelles. Used as efficient drug carriers for doxorubicin (DOX), the micelles acted as synergistic agents for cancer therapy. Dynamic light scattering (DLS) measurements showed that the SPDP micelles had average diameters of 111nm, which decreased to 88nm after the encapsulation of DOX. The mean diameters and size distribution of the disulfide-containing micelles changed obviously in the presence of the reducing agent glutathione (GSH), whereas no changes occurred in the case of redox-insensitive SPGS micelles. DOX could be loaded into both types of micelles, with drug loading content of about 4.0%. A significantly accelerated release of DOX was triggered by GSH for DOX-loaded SPDP micelles, compared with DOX-loaded SPGS micelles. Blank SPGS and SPDP micelles displayed higher inhibition of HeLa and MCF-7 cell proliferation but less cytotoxicity to normal L-02 cells at similar concentrations. Confocal microscopic observation indicated that a greater amount of DOX was delivered into the nuclei of cells following 9 or 12h incubation with DOX-loaded micelles. In vivo studies on H22-bearing Swiss mice demonstrated the superior anticancer activity of DOX-loaded SPDP micelles over free DOX and DOX-loaded SPGS micelles. All of the data presented here suggested that these SPDP micelles may have a dual function, as they are preferentially toxic for tumor cells alone and are efficient and safe carriers for anticancer drugs. STATEMENT OF SIGNIFICANCE: Various nanoscale drug carriers were used to enhance therapeutic effect of many drugs. While, the metabolites of high quantities of carriers may cause additional short- or long-term toxicities. In this study, a new systems based on solanesol derivatives was developed for anticancer drug delivery. There are two features for this system. One is solanesol originated bioactivity of the carrier, which will synergistically facilitate therapeutic effect of the encapsulated drug. The other is the redox-responsive drug release behavior adaptable to the glutathione-rich atmosphere of tumor cell. All the hypothesis have been elucidated in this work through in vitro and in vivo studies. It was found that this drug delivery system may have a dual function, as they are preferentially toxic for tumor cells alone and are efficient and safe carriers for anticancer drugs.