Oliceridine Reduces the EC50 of Remifentanil Required to Attenuate Tracheal Intubation Responses During Anesthesia Induction.

OBJECTIVE: This study aimed to determine whether preemptive oliceridine reduces the half maximal effective concentration (EC₅₀) of remifentanil required to attenuate hemodynamic responses to tracheal intubation during propofol target‑controlled infusion anesthesia. METHOD: In this prospective randomized trial, 50 patients received either 1.5 mg intravenous oliceridine or an equivalent volume of saline (placebo) before anesthesia induction. All patients underwent induction with target-controlled infusion of propofol at an effect-site concentration of 3.0 μg/mL, in combination with remifentanil. The remifentanil concentration for each subsequent patient was determined using Dixon's up-and-down sequential allocation method, based on the preceding patient's hemodynamic response. The primary outcome was the remifentanil EC₅₀ required to prevent a tracheal intubation response, defined as a ≥20% increase in heart rate or blood pressure from baseline or the presence of tearing, muscle tremor, or coughing/choking, with EC₅₀ estimated using probit analysis. RESULTS: The remifentanil EC₅₀ was significantly lower in the oliceridine group (2.52 ng/mL; 95% CI: 2.19-2.80) than in the control group (3.52 ng/mL; 95% CI: 3.27-3.81), corresponding to an approximate 29% reduction in the target effect‑site concentration required to blunt the intubation response. This difference was accompanied by significantly lower induction doses of both remifentanil and propofol (p < 0.01). Additionally, patients who received oliceridine demonstrated lower pain scores immediately after extubation (p < 0.05). CONCLUSION: Preemptive oliceridine significantly reduced the remifentanil EC₅₀ for suppressing tracheal intubation responses, demonstrating an opioid‑sparing effect in this setting. This effect‑site reduction may support hemodynamic stability and help limit remifentanil exposure during anesthesia induction.