Relative bioavailability of gastrodin and parishin from extract and powder of Gastrodiae rhizoma in rat

A rapid, sensitive and reliable UHPLC-ESI-MS/MS method was developed for simultaneous determination of gastrodin and parishin in rat plasma. The LLOQ of the two analytes were 1.00 x 10(-1) and 8.30 x 10(-5) mu g/mL, respectively. The intra-day and inter-day precision were all less than 10% of the relative standard deviation (RSD), whilst the accuracy were all within +/- 15% of the relative error (RE). The proposed method was successfully applied for pharmacokinetics study on the two analytes in rats after oral administration of Gastrodiae rhizoma (GR) extract and powder at low, medium and high dosages. Blood samples were collected from the suborbital vein at predetermined time points and were precipitated using methanol. Chromatographic separations were carried out on a Kinetex XB-C18 column (2.1 mm x 150 mm, 1.7 mu m) with a gradient mobile phase of acetonitrile-water with 0.1% formic acid as a modifier. The pharmacokinetic parameters of the two analytes in rats were obtained and the relative bioavailability of gastrodin and parishin in two formulations were calculated. The results indicated that higher bioavailability was obtained when low dosage of GR powder was used, whereas, higher bioavailability values were obtained when medium and high dosages of GR extract were used. (C) 2014 Published by Elsevier B.V.