Abstract: Objective To determine the median effective dose （ED₅₀） and 95% effective dose （ED₉₅） of oliceridine combined with propofol （plasma target-controlled concentration at 3 μg/mL） for painless gastrointestinal endoscopy. Methods A total of 27 patients scheduled for painless gastrointestinal endoscopy from July to December 2024 were enrolled. All patients received propofol via target-controlled infusion （TCI） at a plasma concentration of 3 μg/mL. The modified Dixon's up-and-down sequential method was used to determine the oliceridine dose （initial dose 1 mg,step size 0.1 mg）. The dose for each subsequent patient was adjusted based on the response of the previous patient （positive response： coughing, retching, or purposeful movement during endoscopy）, with an increase after a positive response and a decrease after a negative response. The study was terminated after 7 response crossovers. Probit regression analysis was used to calculate the ED₅₀, ED₉₅, and their 95% confidence intervals （CIs） for oliceridine. Results The ED₅₀ of oliceridine combined with propofol （TCI 3 μg/mL） for gastrointestinal endoscopy was 0.829 mg （95%CI 0.509-1.053 mg）, and the ED₉₅ was 1.176 mg （95%CI 0.997-4.936 mg）. Conclusion When oliceridine is combined with propofol （TCI 3 μg/mL） for gastrointestinal endoscopy, the ED₉₅ of oliceridine to suppress the insertion response is 1.176 mg. This provides a dose reference for clinical application.

Key words: Oliceridine, Gastrointestinal endoscopy, 95% effective dose, Median effective dose, Propofol