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

Wu-Chu-Yu is a well-known herbal drug used for hypertension. Rutaecarpine and evodiamine are main bioactive components of the medicine. 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 4h) after administration, the concentrations of Rut and Evo in rat whole blood were determined by HPLC, and main pharmacokinetic parameters were calculated. 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. The bioavailability of Rut and Evo was increased along with the increasing of purity (16%-80%) in Wu-Chu-Yu extracts.