Comparative pharmacokinetics of three phenylpropanoids in rat plasma after oral administration of Ramulus Cinnamomi and Ramulus Cinnamomi-Ephedrae Herba herb-couple extract

Objective To investigate the pharmacokinetic characteristics of three phenylpropanoids (cinnamic acid, cinnamic alcohol and coumarin) in Ramulus Cinnamomi (GZ) and Ramulus Cinnamomi-Ephedrae Herba (MH) herb-couple (GZMH). Methods Twelve male Sprague-Dawley rats were randomly and equally divided into the GZ and GZMH herb-couple groups. Blood samples were collected at 0, 0.08, 0.25, 0.5, 0.75, 1.5, 3, 4, 6, 8, 12, 24, 36 and 48 h after oral administration. The three phenylpropanoids in rat plasma were quantified using an ultra-performance liquid-chromatography with tandem mass spectrometry (UPLC-MS/MS) method for pharmacokinetic study. Results In GZMH group, the area under the curve (AUC), mean retention time (MRT) of cinnamic acid and coumarin were increased significantly ( P <0.01, respectively), and biological half-life (t 1/2z ) was obviously shorter ( P <0.05) compared with the GZ group. There were no significant differences in the mean retention time from 0 to ∞ (MRT 0-∞ ), the peak concentration (C max ), the time to peak (T max ) and t 1/2z , except for AUC and MRT 0-t (the mean retention time from 0 to t) of cinnamic alcohol in the GZMH group by comparison to the GZ group ( P <0.01, respectively). The AUC, MRT (both P <0.01) and t 1/2z ( P <0.05) of coumarin were increased significantly, while C max , and T max were decreased slightly by comparison to the GZ group ( P >0.05). Conclusions There were statistically significant differences in some pharmacokinetic parameters of the three compounds between GZ and GZMH groups, which meant that MH could affect the absorption and elimination of the three compounds.