The absorption, distribution, metabolism and excretion of Riccardin D in rats

The present study was designed to investigate the pharmacokinetics following oral and intravenous administration of Riccardin D, an anticancer drug candidate isolated from Chinese liverworts Dumortiera hirsute, in Wistar rats. An HPLC-MS/MS analytical method was developed and validated. The results demonstrated that Riccardin D's bioavailability was 13.4%, 11.4%, and 9.8% after oral administration at 20 mg/kg, 40 mg/kg, and 80 mg/kg, respectively. There was no significant difference in the elimination half-time of Riccardin D at these doses, suggesting that Riccardin D may have linear pharmacokinetic characteristics in rats. The metabolite of Riccardin D in rat was identified as the glucuronide of Riccardin D. Riccardin D showed a wide distribution in various tissues followed by a rapid elimination from most of the tissues tested. Riccardin D was found to distribute widely in the tissues 0.5 h after oral and intravenous administration. The tissue concentrations were markedly decreased 8 h and 6 h after oral and intravenous dosing, respectively. Both Riccardin D and its conjugated metabolite were detected in urine and bile samples while only Riccardin D was detected in feces. Taken together, the study provided valuable pharmacokinetic data for further drug development of Riccardin D.