Effect of Fentanyl and Nalbuphine for Prevention of Etomidate-Induced Myoclonus

Background: Etomidate is a potent intravenous inducing agent with known undesirable side effects such as myoclonus and pain on injection in nonpremedicated patients.

Aims: The aim of this study is to compare the effect of fentanyl and nalbuphine in the prevention of etomidate-induced myoclonus.

Settings And Design: Randomized double-blind, placebo-controlled, and prospective comparative study.

Materials And Methods: A total of 120 patients were randomly allocated to one of the three groups containing 40 patients each for intravenous administration of fentanyl 2 μg/kg diluted in 10 mL normal saline (NS) (Group 1), nalbuphine 0.3 mg/kg diluted in 10 mL NS (Group 2), and only 10 mL NS (Group 3) over 10 min. All groups subsequently received 0.3 mg/kg etomidate by intravenous bolus injection over 15-20 s and were assessed for the severity of pain using Grade IV pain scale and observed for myoclonus for 2 min and graded according to clinical severity. Serum creatinine phosphokinase (CPK) levels were obtained prior and postetomidate injection.

Statistical Analysis: Statistical analysis was performed by the SPSS program version 17.0 for Windows. Tests used are Shaipro-Wilk test, ANOVA, Tukey's multiple comparison test, Tamhane's T2, and the Chi-square test. For all statistical tests, < 0.05 was considered statistically significant with 5% level of significance (α).

Results: The incidence of myoclonus in Group 1 and 2 was 52.5% and 17.5%, respectively, whereas it was 92.45% in Group 3. There was no pain observed in 70%, 92.5%, and 50% of patients in Group 1, 2, and 3, respectively. There was a statistically significant difference in mean CPK level after induction among three groups ( < 0.001).

Conclusion: Nalbuphine is more effective than fentanyl in the prevention of etomidate-induced myoclonus and pain with the minimum rise in CPK levels.