Response Surface Modeling of Remimazolam and Sevoflurane

Overview

This prospective randomized open-label study aims to investigate the pharmacodynamic interaction between remimazolam and sevoflurane during general anesthesia using response surface modeling. Although remimazolam has favorable hemodynamic stability compared with propofol, its hypnotic effect may be less predictable and poorly correlated with conventional sedation monitoring indices such as the bispectral index (BIS). In clinical practice, remimazolam and sevoflurane are often combined during induction and maintenance of anesthesia; however, the optimal interaction between these agents remains unclear. This study will evaluate whether the interaction between remimazolam and sevoflurane is synergistic, additive, or infra-additive using two representative response surface interaction models: the Minto model and the Greco model. BIS values and predicted effect-site concentrations will be analyzed using NONMEM software.

Remimazolam is a recently developed ultra-short-acting benzodiazepine anesthetic with favorable pharmacokinetic characteristics, including a short context-sensitive decrement time and relatively stable hemodynamics. Despite these advantages, remimazolam may exhibit weaker hypnotic potency and inconsistent correlations with conventional anesthetic depth monitors such as BIS. In current clinical practice, anesthesiologists frequently combine remimazolam with volatile anesthetics such as sevoflurane during induction or maintenance of anesthesia. However, the pharmacodynamic interaction between remimazolam and sevoflurane has not been fully elucidated. The present study will investigate the interaction between remimazolam and sevoflurane using response surface modeling. The study will enroll adult patients undergoing elective laparoscopic surgery under general anesthesia. Various combinations of remimazolam infusion rates and end-tidal sevoflurane concentrations will be administered during anesthetic induction. BIS values and predicted effect-site concentrations will be collected and analyzed. Pharmacodynamic interaction analyses will be performed using NONMEM nonlinear mixed-effects modeling software. Both the Minto interaction model and the Greco interaction model will be applied to determine whether the interaction between remimazolam and sevoflurane is synergistic, additive, or infra-additive.