Development of a rapid and sensitive UPLC-MS/MS assay for the determination of TM-2 in beagle dog plasma and its application to a pharmacokinetic study.

A simple and sensitive method based on ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) has been developed for the determination of TM-2, which was a novel semi-synthetic taxane derivative in beagle dog plasma. Cabazitaxel was chosen as internal standard. Following extraction by methyl tert-butyl ether, the chromatographic separation was achieved on a Thermo Syncronis C18 column (50 × 2.1 mm, 1.7 µm) by gradient elution within a runtime of 3.5 min. The mobile phase consisted of (A) acetonitrile and (B) 2 mmol/L ammonium acetate in water. The detection was accomplished using positive ion electrospray ionization in multiple reaction monitoring mode. The MS/MS ion transitions were monitored at m/z 812.39 → 551.35 for TM-2 and 836.36 → 555.26 for IS, respectively. The method was linear for TM-2 (r = 0.9924) ranging from 2.5 to 1000 ng/mL. The intra-day and inter-day precisions (relative standard deviation) were within 8.0 and 17.6%, respectively, and the accuracy (relative error) was less than 2.3%. The extraction recovery ranged from 83.1 to 97.1%. The reliable method was successfully applied to a pharmacokinetic study of TM-2 in beagle dogs after intravenous drip with different doses of 0.6, 1.2, and 2.4 mg/kg, respectively.

Application of an LC-MS/MS method to the pharmacokinetics of TM-2, a potential antitumour agent, in rats.

TM-2 is a novel semi-synthetic taxane derivative, selected for preclinical development based on its greater anticancer activity and lower toxicity compared with docetaxel. In this study, a rapid and sensitive analytical method based on ultra performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed for the determination of TM-2 in rat plasma. The biological samples were extracted with methyl tert-butyl ether and separated on a C18 column (50 mm × 2.1 mm, 1.7 µm) using a mobile phase consisting of acetonitrile and 2 mM ammonium acetate. The standard curves were linear over the range 5-1000 ng/mL in rat plasma. The precision (relative standard deviation, RSD, %) were within 14.5%, and the accuracy (relative error, RE, %) ranged from -1.56 to 2.36%. Recovery and matrix effect were satisfactory in rat plasma. The validated method was successfully applied to pharmacokinetic studies after intravenous administration of TM-2 to rats. The pharmacokinetics of TM-2 in rats were characterized by a large volume of distribution and a long half-life of elimination after single dose (4, 8, and 16 mg/kg), and a good correlation was observed between AUC and dose. The preclinical data will be useful for the design of subsequent trials of TM-2.

Improved oral bioavailability of core-shell structured beads by redispersion of the shell-forming nanoparticles: preparation, characterization and in vivo studies.

In order to increase the dissolution rate and oral bioavailability of bifendate, coated beads with core-shell structure were prepared via a combination use of wet media milling method and bead layering process. Hydroxypropyl cellulose (HPC-SL) and sodium lauryl sulfate (SLS) were found to be the best pair to stabilize the nanosuspension during milling process. A 10:1 ratio of mixture of mannitol and SLS was chosen as most suitable coating matrix to maintain the redispersability of dried nanoparticles in the shell of beads. The mean particle size of the nanosuspension was 139 nm and the zeta potential was -20.2 mV. Nanoscale bifendate particles with a mean diameter of 360 nm could be generated when redispersing the prepared beads in water. The differential scanning calorimetry (DSC) and X-ray powder diffraction (XRPD) analysis indicated that the crystalline state of the drug was not changed. The stability test confirmed that coated beads showed no distinct difference in particle size and dissolution velocity during 6 month storage while liquid nanosuspension was stable no more than 3 weeks. Dissolution rate of coated beads was increased significantly compared with commercially available pills. Likewise, the Cmax and AUC (0→24) of nanosuspension based beads in beagle dogs were 2.40-fold and 1.66-fold greater than that of commercially available pills, respectively. The present work is a reliable approach to stabilize nanosuspension based product, and improve dissolution velocity and bioavailability of poor soluble drugs.

Improving cabazitaxel chemical stability in parenteral lipid emulsions using cholesterol.

Intravenous lipid emulsions of cabazitaxel (CLEs) with a high stability were prepared by adding cholesterol (CH) to provide a new and more suitable delivery system for its administration. The factors affecting CLEs, such as the solubility of cabazitaxel in various oils, different kinds of lecithin, pH, different types of oil phases, and different concentrations of lipoid E80®, CH and poloxamer 188 were investigated systematically. The degradation of cabazitaxel in aqueous solution and lipid emulsion both followed pseudo first-order kinetics. A degradation mechanism was suggested by the U-shaped pH-rate profile of cabazitaxel. A formulation containing 0.5% (w/v) CH and another formulation without CH were made to investigate the protective influence of CH on the chemical stability of CLEs. The activation energy of the two formulations was calculated to be 65.74±6.88 and 54.24±1.43 kJ/mol (n=3), respectively. Compared with the untreated CH, the shelf-life of cabazitaxel with added CH was longer, namely 134.0±23.4 days versus 831.4±204.4 days (n=3) at 4 °C. This indicates that the addition of CH significantly improved the lifetime of cabazitaxel in intravenous lipid emulsions. The hydrogen bonding that takes place between cabazitaxel and CH accounts for the protective effect of CH on the chemical stability of CLEs in two ways: preventing cabazitaxel from leaking and hydrolyzing in aqueous solution and hindering hydrolysis in the oil phase. Finally, the hypothesis was confirmed by LC/TOFMS and Fourier-transform infrared-spectroscopy. As a result, CLEs were obtained successfully by the addition of CH and were stable enough to allow further research.