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

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.

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.

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).

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.