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. 2025 Oct-Dec;19(4):494-497.
doi: 10.4103/sja.sja_55_25. Epub 2025 Sep 3.

Optimal lidocaine propofol mixture for painless induction of anesthesia

Hitham M A Elsayed  1 , Roshdi R Al-Metwalli  1 , Mohammed Abdelraheem  2 , Fawzy Badawy  2
Affiliations

Optimal lidocaine propofol mixture for painless induction of anesthesia

Hitham M A Elsayed et al. Saudi J Anaesth. 2025 Oct-Dec.

Abstract

Objective: To determine the median effective dose (ED50) of 2% lidocaine mixed with propofol for preventing pain during the induction of anesthesia using a modified Dixon's up-and-down method.

Materials and methods: Thirty ASA (American Society of Anesthesiologists) grade I and II patients, aged 18-60 years, undergoing elective surgery were enrolled. Using the modified Dixon's up-and-down method, patients received varying doses of lidocaine mixed with 20 mL of propofol MCT/LCT (Medium Chain Triglyceride/Long Chain Triglyceride) emulsion. The primary outcome was the calculation of the ED50 of 2% lidocaine, defined as the midpoint dose at which 50% of patients experienced painless injection. Secondary outcomes included pain scores during injection, heart rate changes, and withdrawal movements.

Results: Thirty patients completed the study. The ED50 of lidocaine premixed with 20 mL of propofol MCT/LCT emulsion to prevent pain during the induction of anesthesia was 32.14 mg (95% CI = 32.09 mg-32.18 mg), equivalent to 1.46 mg/mL (95% CI: 1.02 mg/mL-1.91 mg/mL). Demographic and clinical characteristics of patients who experienced pain and those who did not were not statistically significant.

Conclusion: Our study concluded that the ED50 of lidocaine premixed with 20 mL of propofol to prevent pain during the induction of anesthesia was 32.14 mg (95% CI = 32.09 mg-32.18 mg), equivalent to 1.46 mg/mL (95% CI: 1.02-1.91 mg/mL).

Keywords: Induction; lidocaine; pain; propofol.

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Conflict of interest statement

There are no conflicts of interest.

Figures

Figure 1
Figure 1
Sequential diagram of intravenous lidocaine doses administered for the prevention of propofol injection
See this image and copyright information in PMC

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