Purpose: Explore the median effective dose of ciprofol for inducing loss of consciousness in elderly patients and investigate how frailty influences the ED₅₀ of ciprofol in elderly patients.
Patients and Methods: A total of 26 non-frail patients and 28 frail patients aged 65– 78 years, with BMI ranging from 15 to 28 kg/m², and classified as ASA grade II or III were selected. Patients were divided into two groups according to frailty: non-frail patients (CFS< 4), frail patients (CFS≥ 4). With an initial dose of 0.3 mg/kg for elderly non-frail patients and 0.25 mg/kg for elderly frail patients, using the up-and-down Dixon method, and the next patient’s dose was dependent on the previous patient’s response. Demographic information, heart rate (HR), oxygen saturation (SpO₂), mean blood pressure (MBP), and bispectral index (BIS) were recorded every 30 seconds, starting from the initiation of drug administration and continuing up to 3 minutes post-administration. Additionally, the total ciprofol dosage during induction, occurrences of hypotension, bradycardia, respiratory depression, and injection pain were recorded.
Results: The calculated ED₅₀ (95% confidence interval [CI]) and ED₉₅ (95% CI) values for ciprofol-induced loss of consciousness were as follows: 0.267 mg/kg (95% CI 0.250– 0.284) and 0.301 mg/kg (95% CI 0.284– 0.397) for elderly non-frail patients; and 0.263 mg/kg (95% CI 0.244– 0.281) and 0.302 mg/kg (95% CI 0.283– 0.412) for elderly frail patients. Importantly, no patients reported intravenous injection pain, required treatment for hypotension, or experienced significant bradycardia.
Conclusion: Frailty among elderly patients does not exert a notable impact on the median effective dose of ciprofol for anesthesia induction. Our findings suggest that anesthesiologists may forego the necessity of dosage adjustments when administering ciprofol for anesthesia induction in elderly frail patients.

Keywords: ciprofol, median effective dose, elderly patients, frailty, loss of consciousness