Effect of Oliceridine Pretreatment on Etomidate-Induced Myoclonus: A Proof-of-Concept Randomized Trial

Etomidate offers hemodynamic stability for anesthesia induction but frequently causes myoclonus. This study evaluated oliceridine, a G-protein biased μ-opioid receptor agonist, for prevention of etomidate-induced myoclonus.

In this double-blind, randomized trial, patients scheduled for elective general anesthesia were allocated to receive either intravenous oliceridine 0.03 mg/kg (Group O) or an equivalent volume of normal saline (Group NC) 5 minutes before anesthesia induction with 0.3 mg/kg etomidate administered over 30-60s. The primary outcome was the incidence of myoclonus within 2 minutes after etomidate administration. Secondary outcome was the severity of myoclonus. Perioperative hemodynamic variables, the incidence of adverse events and postoperative pain intensity (assessed using the Numerical Rating Scale) were recorded.

Of 93 patients who completed the study, Group O showed lower myoclonus incidence (10.9% vs 57.4%; P < 0.001), with relative risk 0.189 (95% CI: 0.080-0.421) and the number needed to treat 2.147 (95% CI: 1.495-3.222). No severe myoclonus occurred in Group O (vs 2.1% in NC), with fewer mild-moderate cases. On postoperative day 1, Group O also had lower pain scores both at rest (0.9 ± 0.8 vs 1.3 ± 0.9; P = 0.020) and during activity (1.2 ± 1.1 vs 1.8 ± 1.1; P = 0.017). Hemodynamic variables were comparable, and no significant differences in adverse events were detected between groups.

In this single-center proof-of-concept randomized trial of ASA I-II patients, pretreatment with oliceridine (0.03 mg/kg) before etomidate induction reduced the incidence of etomidate-induced myoclonus. The statistically lower postoperative day 1 pain scores in the oliceridine group should be interpreted cautiously, and these findings warrant confirmation in larger multicenter trials involving broader patient populations.