Comparative pharmacokinetic and bioavailability study of lobetyolin in rats after administration of lobetyolin and Codonopsis pilosula extract by ultra-performance LC-tandem mass spectrometry.

Codonopsis pilosula (CP) is a traditional Chinese medicine used to invigorate spleen, replenish lung, nourish blood and engender fluid. A rapid, selective and sensitive ultra-performance LC-tandem mass spectrometry method was developed and validated to determine lobetyolin in rat plasma. The calibration curve showed good linearity over a concentration range of 0.46-1000 ng/mL for lobetyolin. The extraction recovery ranged from 72.5% to 89.1% with matrix effects of 81.6%-107.8%. The intra- and inter-batch precision and accuracy were 0.02-14.4% and -13.9% to -1.36%, respectively. The method was successfully applied for the bioavailability study of lobetyolin in rats after oral administration of pure lobetyolin and CP extract. Results showed that the elimination half-time (t1/2 ) and the area under the concentration-time curve from zero to infinity of lobetyolin in CP extract were statistically different from those of the pure monomer (P < 0.05). However, the time to reach the maximum plasma concentration (Tmax ) and the maximum concentration (Cmax ) showed no significant differences between the two treatments. Furthermore, the bioavailability of lobetyolin in the experimental group was only 3.90%, significantly lower than that of the CP extract group (6.97%). The low bioavailability indicated that this component may be absorbed poorly or metabolized extensively in rats. Our results will provide useful information for further preclinical studies and formulation preparation of lobetyolin.