Preclinical pharmacokinetic evaluation of a new formulation of a bifendate solid dispersion using a supercritical fluid chromatography-tandem mass spectrometry method.

In order to evaluate the pharmacokinetic characteristics of a new formulation of a bifendate solid dispersion in beagle dogs, a novel, sensitive and rapid supercritical fluid chromatography-tandem mass spectrometry (SFC-MS/MS) method was established and validated. Plasma samples were subjected to liquid-liquid extraction with ethyl acetate. Separation of bifendate and diazepam (internal standard, IS) was performed on an HSS C18 SB column (3×100mm, 1.8μm) with a mobile phase consisting of CO2 (≥99.99%) - methanol (95:5, v/v) at a flow rate of 2mL/min and the compensation solvent was methanol with 2% formic acid at a flow rate of 0.2mL/min. A tandem triple quadrupole mass spectrometer was operated in multiple reaction monitoring (MRM) mode with an electrospray ionization (ESI) source. Quantification of the ion transitions was at m/z 419.2→387.0 and 284.5→193.2 for bifendate and IS, respectively. The method was sensitive with a lower limit of quantification (LLOQ) of 0.5ng/mL and linear over the concentration range 0.5-250ng/mL. All the validation data, such as precision, accuracy, extraction recovery and matrix effect, were all within acceptable criteria. The method has been successfully applied to a pharmacokinetic study of bifendate in beagle dogs after oral administration of a bifendate solid dispersion.