Part I: Dose escalation
In a previous phase 1 study, the results indicated that ciprofol 0.4 mg/kg, administered as a single i.v. bolus dose, was suitable for inducing general anesthesia in healthy adults. Therefore, in this phase 2a study, we chose 3 doses of ciprofol (0.3, 0.4, 0.5 mg/kg) and 2 doses of propofol (2.0, 2.5 mg/kg). The plan was to enroll 10 patients in each group, with 0.4 mg/kg ciprofol selected as the initial escalation dosage, based on the results of a phase 1 study. If 10 patients in the ciprofol 0.4 mg/kg all successfully achieved 100% induction of anesthesia with a single bolus injection, the next step was administration of a single dose of 0.3 mg/kg for induction, with a dose reduction of 0.1 mg/kg for the 10 patients (ciprofol 0.3 mg/kg group). If one or more of the 10 patients who received a dose of 0.4 mg/kg failed to achieve satisfactory anesthesia, a dose of 0.5 mg/kg was given to another 10 patients, with an increment in the dose of 0.1 mg/kg (ciprofol 0.5 mg/kg group). It should be noted that the investigator and sponsor needed to decide whether patients could receive the next dose, after they had evaluated the safety and efficacy outcomes of the previous dose. For propofol, doses of 2.0 mg/kg and 2.5 mg/kg were arbitrarily chosen as guided by a previous study [Finally, 9, 8 and 8 patients were scheduled to be enrolled in the 3 ciprofol groups and 10 in each propofol group.