Effects of the Chinese Herbal Formulation (Liu Wei Di Huang Wan) on the Pharmacokinetics of Isoflavones in Postmenopausal Women

Abstract

A combination of soy isoflavones andLiu Wei Di Huang Wan(LWDHW) is potentially effective for postmenopausal women with intolerable vasomotor episodes who are not suitable candidates for hormonal therapy. The objective of this open-label, three-phase, crossover study was to determine the influence of both single and multiple oral doses of LWDHW on isoflavone pharmacokinetics in healthy postmenopausal women. Eleven subjects were assigned to receive the following regimens in a fixed sequence with washout periods of at least one week: Phase A, a single oral dose of soy milk; Phase B, a single oral dose of soy milk coadministered with LWDHW; and Phase C, multiple oral doses of LWDHW for 14 days followed by a single oral dose of soy milk. Blood samples were collected and mixed withβ-glucuronidase/sulfatase to hydrolyze isoflavone conjugates to their respective aglycones (i.e., daidzein and genistein) and were determined using high performance liquid chromatography. The pharmacokinetic parameters analyzed were maximal plasma concentrationCmax, time to reach peak concentrationTmax, area under the plasma concentration-time curve (AUC), and half-life (t1/2). The results found no statistically significant differences in pharmacokinetic parameters of daidzein and genistein among the three regimens.