Objective: To probe into the pharmacokinetic characteristics of tacrolimus (FK506) in dextran sodium sulfate (DSS)-induced ulcerative colitis (UC) in rats. Methods: Twelve rats were randomly divided into the UC group and the normal group

with 6 cases in each group. The UC group was given 5% DSS for 7 d to induce the UC model. On the 8th d

two groups were given FK506 for 1 mg/kg by gavage. Blood samples were collected at different time points before and after administration to determine the concentration of FK506

and the main pharmacokinetic parameters of two groups were compared and analyzed. Results: Compared with the normal group

the exposure intensity of FK506 in the UC group increased

the AUC0-t increased by 44.06%

the half-life was prolonged by 1.85 h (nearly 50%)

the in vivo retention time (MRT0-∞) was prolonged by 37.0% and the drug clearance rate increased by 37.0% (P<0.05). Conclusion: The pharmacokinetics of FK506 in rats is affected by UC status

resulting in decreased FK506 metabolism

prolonged half-life

and increased exposure intensity

which may be related to the effect of UC status on P-glycoprotein and CYP3A enzyme activities.