Abstract:Objective：To investigate the conveying and drug release in vivo of colon target pellets of Rhubarb in rats.Methods：The rhubarb colon-targeted pellets were administered by homemade rat mouth gag. The rats were respectively killed at different time points after administering，and the gastrointestinal tracts were dissected. The appearance of pellets was observed and the sum of pellets were counted. The pellets distribution rates in the digestive tract in rats were calculated at different time point after administering. After the residue level of aloeemodin， emodin and chrysophanol in pellets were respectively determined by HPLC，also the emodin in rats，gastrointestinal tissue and content. The accumulative releasing was calculated and the drug concentration-time curve in the gastrointestinal tract was drawn，then the drug release property was evaluated.Results：The pellets were transferred to colon completely and obvious late release effect. The colon distribution rate could reach the highest after 10~12 h，52.7%. In 8~16 h， drugs had a high concentration in the cecum and colon. Final release dosage percentage was 88.99%.Conclusion：Rhubarb colon-targeted pellets possessed the characteristic of drug release in colon.

Key words:rhubarb colon-targeted pellets,rat,digestive tract,distributiont,drug releasing