Preparation, Characterization and Pharmacokinetic Study of Xiangfu Siwu Decoction Essential Oil/β-Cyclodextrin Inclusion Complex

Xiang-Fu-Si-Wu Decoction (XFSWD), a famous Chinese herbal formula, is considered an effective prescription for treating primary dysmenorrhea. The essential oil is a significant effective ingredient of XFSWD. However, its volatility, instability and poor water-solubility influence its pharmacodynamic effects. β-Cyclodextrin (β-CD) has the intrinsic ability to form specific inclusion complexes with such drugs to enhance their stability, solubility and bioavailability. The aim of this study was thus to compare the pharmacokinetic characteristics and the oral bioavailability of XFSWD essential oil (XEO) and its β-CD inclusion complex after oral administration to rats. A simple, rapid, and sensitive ultra-high performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method was developed for the simultaneous quantification of five active components of XEO in rat plasma. The in vivo data showed that XEO/β-CD inclusion complex displayed higher maximum plasma concentration (C(max)), longer half-time (T(1/2)) and bigger area under the concentration-time curve (AUC(0–24 h)). These results demonstrated that the formation of β-CD inclusion complex has significantly increased the oral bioavailability of the drugs in rats than free oil.