Midazolam and Propofol Synergism for Induction of Anesthesia

Kang, Jai Ik; Jung, Bae Jung; Choe, Won Joo; Kim, Byung Jung; Lee, Seung Joon; Choi, Hyun; Kil, Ho Yeong; Yoon, Young Joon

Abstract

The mechanism by which propofol exerts its action is poorly understood, but may involve a non-specific effect on lipid membrane and has been shown to potentiate GABA-mediated synaptic inhibition. And, midazolam also acts through GABA receptor mediated increased chloride conductance. The aim of this study was to evaluate the dose response of midazolam, propofol and combination of these drugs, and determine possible interaction between two drugs in patients. The effect of propofol on the dose response curve for midazolam was studied in 260 nonpremedicated ASA physical status I or II female patients who were scheduled for elective operation. The response to the verbal command was used as an end-point of hypnosis. Dose response curves for midazolam, propofol, and their type of interaction was determined using Instat software package, nonlinear regression analysis, and algebraic(fractional) analysis of interaction. ED of midazolam and propofol was 0.11 mg/kg, 1.13 mg/kg and ED95 was 0.18 mg/kg, 1.67 mg/kg respectively. ED50 of combined drug(midazolam+propofol) in comhined dose response curve was 29% of each drug and the type of interaction between two drugs was found to be synergistic.