The pharmacokinetics of a novel anti‐tumor agent, β ‐elemene, in Sprague‐Dawley rats

β ‐Elemene, a natural sesquiterpene, is a novel anti‐tumor agent. The pharmacokinetics of β ‐elemene after single i.v. administration have been investigated in male SD rats. β ‐Elemene was administered at three doses (50, 75 and 100 mg/kg) and a full pharmacokinetic profile was obtained. β ‐Elemene was metabolized extensively and eliminated rapidly. High permeability of β ‐elemene through the blood–brain barrier was found following i.v. administration based on the brain/plasma ratio. Following i.v. administration, the drug was eliminated primarily as metabolite and minimally as unchanged drug. Cumulative fecal, biliary and urinary excretion of β ‐elemene in rats was 0.61%, 0.06% and 0.003% of the administered dose (75 mg/kg) at 32 h after administration, respectively. These results indicate that biotransformation may be the main elimination passage of β ‐elemene. The metabolism of β ‐elemene was extensive and the structure of the metabolite (M1) in rat bile was determined by GS/MS and NMR analysis. Copyright © 2005 John Wiley & Sons, Ltd.