Determination of bergenin in rat plasma by high-performance liquid chromatography.

A simple, sensitive, selective and reproducible reversed-phase high-performance liquid chromatography (HPLC) method was developed for the determination of bergenin in rat plasma after intravenous administration. Acetaminophen was successfully used, as internal standard (IS) for calibration. The chromatographic separation was accomplished on a reversed-phase C18 column using a mobile phase consisting of methanol-water (20:80, v/v, pH 2.50) and a detection wavelength of 275 nm. Retention times of bergenin and acetaminophen were approximately 9.9 and 6.1 min and no interfering peak of the blank plasma chromatograms was observed. Good linearity was achieved in the range of 0.3 - 100 microg/ml (r2 = 0.9998). The extraction recoveries of bergenin from plasma was 70.82%, 69.44%, 70.98% at concentrations of 5, 50, 100 microg/ml. Intra-assay and inter-assay variabilities were 0.92 - 2.60% and 2.31 - 2.95%, respectively. The accuracy was validated by relative error (RE%), which was in the range of -0.05 - 1.74%. The capability of the assay to pharmacokinetic studies was demonstrated by the determination of bergenin in plasma after intravenous administration to rats in doses of 7.5 mg/kg, 15.0 mg/kg, and 30.0 mg/kg, using water as the solvent. The half-lives for distribution and elimination are not related to administered doses. A biphasic phenomenon with a rapid distribution followed by a slower elimination phase was observed from the plasma concentration-time curve and the pharmacokinetics was based on first order kinetics.