Background Remimazolam besylate is increasingly used for procedure sedation anesthesia (PSA) in gastrointestinal endoscopy, but age‑specific dosing for elderly patients is unclear. This study determined the median effective dose (ED₅₀) for successful gastroscope insertion without patient movement in two geriatric age groups. Methods In a prospective single‑center trial, 51 patients were assigned by age to Group L (65–70 years, n = 27) or Group H (> 70 years, n = 24). All received 0.1 µg/kg sufentanil, followed by an initial remimazolam bolus of 0.15 mg/kg (Group L) or 0.10 mg/kg (Group H). Doses were adjusted in 0.02 mg/kg steps using a modified Dixon up‑and‑down method based on the previous patient’s response (movement vs. no movement). Primary outcome was ED₅₀ for successful insertion. Secondary outcomes were the induction time, hemodynamic changes, hypoxemia, and other adverse events. Results ED50 was 0.171 mg/kg in Group L, significantly higher than 0.098 mg/kg in Group H (P < 0.001); probit analysis gave similar values (0.175 mg/kg vs. 0.106 mg/kg). ED₉₅ values were 0.235 mg/kg (Group L) and 0.131 mg/kg (Group H). Induction times were comparable (27 s vs. 25 s, P = 0.394). Both groups achieved rapid induction (< 1 min) and recovery time. Transient SpO₂ drops (< 95%) occurred in 1 patient (3.7%) in Group L and 2 patients (8.3%) in Group H; no hypoxemia (SpO₂ < 90%) was observed. Hypotension occurred in 7.4% (Group L) and 20.8% (Group H, P = 0.238). Movement incidence and VAS scores were similar. Conclusions For elderly patients undergoing gastroscopy, the ED₅₀ of remimazolam is 0.171 mg/kg for ages 65–70 and 0.098 mg/kg for > 70 years combined with 0.1 µg/kg sufentanil. These ED50 values are specific to this sufentanil co-administration regimen; the ED50 of remimazolam alone would be higher. This regimen provides rapid onset and recovery with low respiratory and circulatory risk in this cohort. However, the higher incidence of hypotension (20.8%) in patients > 70 years warrants increased vigilance for circulatory depression in this age group. Trial registration Chinese Clinical Trial Registry, No:ChiCTinR2500110081. Registered on 30 September 2025. Prospective registration. <a href="http://www.chictr.org.cn">http://www.chictr.org.cn</a>. Graphical Abstract

Age‑stratified median effective dose (ED₅₀) of remimazolam besylate for successful gastroscope insertion without body movement in geriatric patients

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2026年5月21日

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Si-Qi Hao,
Zhe Ma,
Fang-Yu Zhang,
Yi-Xin Hu,
Li-Xin An

摘要

Background

Remimazolam besylate is increasingly used for procedure sedation anesthesia (PSA) in gastrointestinal endoscopy, but age‑specific dosing for elderly patients is unclear. This study determined the median effective dose (ED₅₀) for successful gastroscope insertion without patient movement in two geriatric age groups.

Methods

In a prospective single‑center trial, 51 patients were assigned by age to Group L (65–70 years, n = 27) or Group H (> 70 years, n = 24). All received 0.1 µg/kg sufentanil, followed by an initial remimazolam bolus of 0.15 mg/kg (Group L) or 0.10 mg/kg (Group H). Doses were adjusted in 0.02 mg/kg steps using a modified Dixon up‑and‑down method based on the previous patient’s response (movement vs. no movement). Primary outcome was ED₅₀ for successful insertion. Secondary outcomes were the induction time, hemodynamic changes, hypoxemia, and other adverse events.

Results

ED₅₀ was 0.171 mg/kg in Group L, significantly higher than 0.098 mg/kg in Group H (P < 0.001); probit analysis gave similar values (0.175 mg/kg vs. 0.106 mg/kg). ED₉₅ values were 0.235 mg/kg (Group L) and 0.131 mg/kg (Group H). Induction times were comparable (27 s vs. 25 s, P = 0.394). Both groups achieved rapid induction (< 1 min) and recovery time. Transient SpO₂ drops (< 95%) occurred in 1 patient (3.7%) in Group L and 2 patients (8.3%) in Group H; no hypoxemia (SpO₂ < 90%) was observed. Hypotension occurred in 7.4% (Group L) and 20.8% (Group H, P = 0.238). Movement incidence and VAS scores were similar.

Conclusions

For elderly patients undergoing gastroscopy, the ED₅₀ of remimazolam is 0.171 mg/kg for ages 65–70 and 0.098 mg/kg for > 70 years combined with 0.1 µg/kg sufentanil. These ED₅₀ values are specific to this sufentanil co-administration regimen; the ED₅₀ of remimazolam alone would be higher. This regimen provides rapid onset and recovery with low respiratory and circulatory risk in this cohort. However, the higher incidence of hypotension (20.8%) in patients > 70 years warrants increased vigilance for circulatory depression in this age group.

Trial registration

Chinese Clinical Trial Registry, No:ChiCTinR2500110081. Registered on 30 September 2025. Prospective registration. http://www.chictr.org.cn.

Graphical Abstract