Median effective dose and 95% effective dose of oliceridine combined with ciprofol for painless gastroscopy: a dose-finding study based on Dixon's up-and-down method.

OBJECTIVE: To determine the median effective dose and estimate 95% effective dose of oliceridine combined with ciprofol for suppressing gastroscope insertion responses, stratified by sex. METHODS: This prospective, sex-stratified trial enrolled patients between 16 January and 31 March 2026, at the General Hospital of Northern Theater Command. Patients, stratified into separate male and female cohorts, received an individualized dose of oliceridine followed by a fixed dose of ciprofol (0.4 mg/kg) for anesthesia induction. The oliceridine dose was determined using a modified Dixon up-and-down method, with an initial dose of 0.02 mg/kg. Subsequent doses increased or decreased by a ratio of 1.0:1.1 based on positive or negative responses. The positive response was defined as retching, coughing, body movement, or a greater than 30% increase in mean arterial pressure or heart rate within 1 min of insertion. The trial terminated upon reaching seven consecutive response reversals in each cohort. RESULTS: A total of 29 male and 32 female patients completed the study. The ED50 and ED95 values of oliceridine were 12.74 μg/kg (95% CI: 9.48-14.76) and 17.69 μg/kg (95% CI: 15.32-40.14) in females, compared with 17.37 μg/kg (95% CI: 15.59-19.01) and 20.98 μg/kg (95% CI: 19.22-32.47) in males, respectively. In both the male and female cohorts, ciprofol consumption was significantly lower in the negative-response group than in the positive-response group, whereas oliceridine requirements were higher. At gastroscope insertion, both MAP and HR decreased, with the negative-response group showing significantly lower values. SpO2 levels at insertion were significantly higher than baseline values. There were no significant differences in the incidence of adverse events between the two sexes. CONCLUSION: For day-case painless gastroscopy, the ED50 of oliceridine combined with ciprofol (0.4 mg/kg) was 12.74 μg/kg in females and 17.37 μg/kg in males, with ED95 estimates of 17.69 μg/kg and 20.98 μg/kg, respectively.