Pharmacokinetic comparisons of rutaecarpine and evodiamine after oral administration of Wu-Chu-Yu extracts with different purities to rats

Ethnopharmacological relevance: Wu-Chu-Yu is a well-known herbal drug used for hypertension. Rutaecarpine and evodiamine are main bioactive components of the medicine. Materials and methods: A sensitive and specific HPLC method was developed to analyze rutaecarpine (Rut) and evodiamine (Evo) in rat whole blood. The pharmacokinetics of Rut and Evo after oral administration of Wu-Chu-Yu extracts with different purities to rats was compared to evaluate the effect of purity of Wu-Chu-Yu extracts on the absorption of Rut and Evo. Male Sprague-Dawley rats were given Wu-Chu-Yu extracts with different purities (high, medium and low) approximately the same doses of equivalent to Rut (40 mg/kg) and Evo (31 mg/kg). The contents of Rut and Evo were 45 and 35%, 28 and 21%, 9 and 7% in high, medium and low purity extracts, respectively. At different time points (0.25, 0.5, 0.75, 1, 1.5, 2, 2.5, 3 and 4 h) after administration, the concentrations of Rut and Evo in rat whole blood were determined by HPLC, and main pharmacokinetic parameters were calculated. Results: The results indicated that the absorption of Rut and Evo in Wu-Chu-Yu extracts was improved when compared with the pure Rut and Evo and there were significant differences among different groups. Conclusions: The bioavailability of Rut and Evo was increased along with the increasing of purity (16%-80%) in Wu-Chu-Yu extracts. (C) 2011 Elsevier Ireland Ltd. All rights reserved.