To study the effect of three different doses of dexmedetomidine as premedication on the incidence and severity of etomidate-induced myoclonus

Background and Aims: Etomidate, a carboxylated imidazole is a rapid-acting nonbarbiturate, nonopioid hypnotic agent that has unique hemodynamic stability, favorable toxic profile, and rapid recovery after a single dose. Myoclonus may occur when etomidate is used for induction of general anesthesia. We tested the hypothesis that premedication with different doses of dexmedetomidine reduces the incidence and severity of myoclonus as well as the side effects induced by etomidate. Materials and Methods: This prospective, randomized, double-blinded study was done on ninety patients undergoing elective surgical procedures who were randomly allocated into three groups for intravenous administration of premedication of 0.3 μg/kg (Group DL), 0.5 μg/kg (Group DM), and 1.0 μg/kg (Group DH) dexmedetomidine in 100 mL normal saline 10 min before induction of general anesthesia with 0.3 mg/kg etomidate. The primary outcome was to evaluate the incidence of etomidate-induced myoclonus, while the severity of etomidate-induced myoclonus and the incidence of adverse effects were taken as secondary outcomes. Results: The incidence of etomidate-induced myoclonus was reduced by 13.3% in Group DL, 36.7% in Group DM, and 56.7% in Group DH. The severity of myoclonus was significantly reduced in Group DH as compared to Group DL and DM (P = 0.001). Side effects such as bradycardia, hypotension, and nausea and vomiting were comparable among the three groups. Conclusion: Premedication with dexmedetomidine 1 μg/kg before induction of general anesthesia not only resulted in a 56.7% reduction in the incidence of etomidate-induced myoclonus but also reduced the severity of myoclonus, without inducing any significant adverse effects, as compared to other two doses.