Objective To evaluate the safety,tolerability and pharmacokinetic profiles of naldemedine in Chinese healthy adult subjects after single and multiple administrations.Methods After single and multiple oral administrations of naldemedine to 10 healthy Chinese subjects,the plasma concentrations of naldemedine and its metabolite(nor-naldemedine)were measured by liquid chromatography-mass spectrometry,and the pharmacokinetic parameters were calculated by Phoenix WinNonlin 8.3.1 software.Results Compared with single administration,naldemedine showed no significant change in the tmax(1.06 h for single and 1.08 h for multiple)and Cmax(4.16 ng·mL-1 for single and 4.11 ng·mL-1 for multiple),higher AUC0-τ than that of single(23.88 ng·h·mL-1 for single and 28.93 ng·h·mL-1 for multiple),slightly prolonged t1/2(9.26 h for single,12.50 h for multiple),there was a slight drug accumulation after multiple doses(accumulation ratio of 0.99 for Cmax and 1.22 for AUC);t1/2(18.10 h for single,29.30 h for multiple),Cmax(0.19 ng·mL-1 for single,0.38 ng·mL-1 for multiple),and AUC0-τ(3.13 ng·h·mL-1 for single,6.02 ng·h·mL-1 for multiple)were all significantly elevated with nor-naldemedine,and the tmax(single was 3.49 h and multiple was 3.56 h)did not change significantly.The Cmax ratio and AUC ratio of metabolites to naldemedine were significantly elevated,and accumulation was present after multiple administrations(accumulation ratio of 2.01 for Cmax and 1.95 for AUC).All adverse events that occurred after treatment were mild.Conclusion After multiple oral administrations of 0.2 mg naldemedine tablets to Chinese healthy subjects(single dose on day 1 and once daily on days 4-13),the drug was eliminated rapidly with mild accumulation,and reached a steady state before the second dose of the multiple-dosing phase,and the product has a favorable safety and tolerability profiles.