Abstract: Objective To compare the inhibitory effects of Butorphanol and Dezocine on Etomidate-induced myoclo⁃ nus. Methods A total of 150 patients with ASA physical statusⅠorⅡ, aged 40-65 yr, with body mass index (BMI) of 20- 25 kg/m², scheduled for elective operations under general anesthesia, were included in this study. Patients were randomly al⁃ located into three groups (A, B and C) with 50 patients in each group. Group A was given intravenous Butorphanol 15 μg/kg for 30 s, group B was given Dezocine 0.1 mg/kg and group C was given equal volume of saline. After 2 min, etomidate 0.3 mg/kg was administrated to three groups. The occurrence and severity of myoclonus were recorded for 2 min after administration of Etomidate. The mean arterial pressure (MAP), heart rate (HR), pulse oxygen saturation (SpO2) and Bispectral index (BIS) were recorded at the time points before induction (T0), 2 min after the experimental drug treatment (T1), and 2 min after Etomi⁃ date treatment (T2). At the same time, the concentration of serum potassium was determined at T0 and 5 min after endotrache⁃ al intubation (T3) respectively. Results The positive incidences of myoclonus were 12% in group A, 22% in group B and 74% in group C, respectively. Compared with group C, the positive incidence rates of myoclonus and myoclonus scales were significantly lower in group A and group B (P < 0.05), but no significant difference between group A and group B (P > 0.05). Compared with T0, there was no significant difference in the potassium concentration between patients without myoclonus (grade 0) and patients with myoclonus (grade 1 and grade 2) at T3 (P > 0.05). There was a significant increase in potassium concentration in patients with grade 3 (P < 0.05). There were no significant differences in MAP, HR, SpO2 and BIS values at T0, T1 and T2 between three groups of patients (P＞0.05). Conclusion Pre-treatment of Butorphanol (15 μg/kg) or Dezocine (0.1 mg/kg) can reduce the Etomidate-induced myoclonus. At the same time, both therapies show no different effects on cir⁃ culation and respiration system.

Key words: Butorphanol, Etomidate, myoclonus, receptors, opioid, kappa, Dezocine