AIM: To study chronopharmacokinetics of helicid and its metabolites. METHODS: An HPLC-MS method for simultaneous determination of helicid and its three phase I metabolites were established and validated. At 8:00, 14:00 and 0:00, the rats were given helicid 50 mg/kg by gavage, respectively. Blood samples were collected from ophthalmic venous plexus. Then plasma concentration was measured. Pharmacokinetic behaviors of the original drug and its metabolites after administration at different time points were calculated and compared. RESULTS: This established HPLC-MS/MS method was successfully applied to simultaneous determination of helicid and its three metabolites in rat plasma after intragastric administration. Using AUC

AIM: To investigate the absorption of helicid in different segments of intestine based on rat everted intestine sac model. METHODS: To establish a high-performance liquid chromatography method for simultaneous determination of helicid and its metabolite. Krebs-ringer solution containing helicid was added to everted intestine sacs of different segments (duodenum, Jejunum, ileum and colon). Drug concentration in sacs was determined at different time points (5, 10, 15, 30, 45, 60, 75, 90 min). Adsorptions of helicid in four intestinal segments were compared. RESULTS: This high-performance liquid chromatography was successfully applied to the simultaneous determination of helicid and its metabolite. Absorption of helicid was rapid and time-dependent. The absorption and metabolism of helicid in duodenum segment were higher than these in other segments. CONCLUSION: The duodenum segment is the main site of segmental absorption and metabolism of helicid. This is the first report on intestinal segment metabolism of helicid.