Pharmacokinetic, bioavailability and tissue distribution study of astilbin in rats

Objective The purpose of this study is to reveal the pharmacokinetic profiles of astilbin with various doses in rats and investigate the oral absolute bioavailability and tissue distribution of astilbin after oral administration. Methods Wistar rats were orally administered astilbin 12, 24 mg/kg and intravenous administered astilbin 6 mg/kg randomly. The concentration of astilbin in rat plasma and various tissue samples was determined by LC‐MS/MS method. Noncompartmental pharmacokinetic parameters including AUC and t1/2 were calculated from plasma concentration–time data of astilbin with the DAS 3.0. Key findings After oral administration of astilbin 12 and 24 mg/kg to rats, the oral absolute bioavailability of astilbin were 1.16 ± 0.695% and 1.27 ± 0.379%; the plasma elimination half‐lives (t1/2) were 101 ± 35.8 and 109 ± 25.3 min, respectively. Astilbin had a rapid absorption and a wide distribution throughout the whole body except liver and fat following oral administration. Astilbin could penetrate the blood–brain barrier of rat. Conclusions The oral absolute bioavailability of astilbin is poor because of the low permeability and solubility. Both oral absorption and clearance of astilbin in rats are rapid after oral administration.