Zhaoping Liu

In vitro and in vivo evaluation of silybin nanosuspensions for oral and intravenous delivery

In this study, we evaluate the effect of particle sizes on the physicochemical properties of silybin and identify the influence of silybin nanosuspensions on its permeation across the Caco-2 cell monolayer. In vivo pharmacokinetic evaluation of silybin nanosuspensions was also carried out in beagle dogs. TEM, AFM and SEM analyses revealed the effect of homogenization pressure on particle size and morphology, and confirmed the existence of a surfactant-stabilizer film on the surface of nanoparticles. DSC and XRPD experiments manifested that the crystalline state was maintained as particle size was reduced and the enhanced dissolution property was due to the increased surface area. Nanosuspensions had a significant influence on drug transport across the Caco-2 cell monolayer and the enhanced dissolution velocity was responsible for the increased permeability. A pharmacokinetics study in beagle dogs further confirmed the in vitro results and demonstrated that oral administration of silybin nanosuspensions significantly increase its bioavailability compared to the coarse powder. Nanosuspensions of silybin with smaller particle size reveal a higher potential to increase their oral bioavailability; while for intravenous infusion the lower pressure produced silybin nanosuspensions appeared to maintain a more sustained drug release profile.

In vitro antitumor activity of silybin nanosuspension in PC-3 cells

The present study aims to evaluate the antitumor activity of silybin nanosuspension on human prostatic carcinoma PC-3 cell line in vitro. Silybin nanosuspension was prepared by the high pressure homogenization (HPH) method. MTT assay, observation of morphological changes and apoptotic body showed that silybin nanosuspension could significantly enhance the in vitro cytotoxicity against PC-3 cells compared to the silybin solution. Flow cytometric (FCM) analysis demonstrated that silybin nanosuspension induced G1 cycle arrest and apoptosis in PC-3 cells. Thereby, the overall results suggest that the silybin nanosuspension represents a potential source of medicine for the treatment of human prostate cancer.

Development and in vitro evaluation of deacety mycoepoxydiene nanosuspension

Deacety mycoepoxydiene (DM), extracted from Phomopsis sp. A123 of thalassiomycetes, is a novel and potent anti-cancer agent. Due to its physicochemical characteristics, the drug, a poorly water-soluble weak acid, shows poor solubility and dissolution characteristics. To improve the solubility and dissolution, formulation of DM as nanosuspension has been performed in this study. Nanosuspensions were developed by high-pressure homogenization (HPH) (DissoCubes(®) Technology) and transformed into dry powder by freeze-drying. The nanosuspension produced was then investigated using optical microscope, photon correlation spectroscopy (PCS), zeta potential measurement, SEM, TEM, AFM, DSC and XRD. To verify the theoretical hypothesis on the benefit of increased surface area, in vitro saturation solubility and dissolution profile were investigated. In addition, the in vitro cell cytotoxicity was examined. Results showed that a narrow size distributed nanosuspension composed of unchanged crystalline state with a mean particle size of 515±18 nm, a polydispersity index of 0.12±0.03 and a zeta potential of -23.1±3.5 mV was obtained. In the in vitro dissolution test an accelerated dissolution velocity and increased saturation solubility could be shown for the MD nanosuspension. The in vitro cytotoxicity experiments provided evidence for an enhanced efficacy of the DM nanosuspension formulation compared to free DM solution. Taken together, these results illustrate the opportunity to formulate DM in nanosuspension form as an anti-prostate cancer delivery system.

A rapid and sensitive LC-MS/MS assay for the quantitation of deacetyl mycoepoxydiene in rat plasma with application to preclinical pharmacokinetics studies

The purpose of this study was to develop and validate a high-performance liquid chromatographic-tandem mass spectrometric (LC-MS/MS) method for analysis of the deacetyl mycoepoxydiene in rat plasma. The analyte and internal standard (I.S.), benorilate, were extracted from rat plasma by precipitation protein and separated on a C(18) column using acetonitrile-0.5% formic acid as mobile phase. Detection was performed using a turbo-spray ionization source and mass spectrometric positive multi-reaction-monitoring-mode (+MRM) at an ion voltage of +4800 V. The assay was linear over the concentration range 5-5000 ng/mL with the lowest limit of quantification (LLOQ) of 5 ng/mL. The method also afforded satisfactory results in terms of the sensitivity, specificity, precision (intra- and inter-day, RSD<5.8%), accuracy, recovery as well as the stability of the analyte under various conditions. The method was successfully applied to a preclinical pharmacokinetic study in rats after a single intravenous administration of deacetyl mycoepoxydiene 10 mg/kg.