Effect of chronic alcohol intake on half- effective target effect- site concentration of propofol required for loss of consciousness

Abstract

Objective To evaluate the effect of chronic alcohol intake on the sedative potency of propofol through investigating the effect of chronic alcohol intake on the half-effective target effect-site concentration ( EC50 )of propofol required for loss of consciousness in patients. Methods Fifty male ASA Ⅰ or Ⅱ patients, aged 25-60 yr, weighing 50-80 kg, scheduled for elective surgery, were divided into 2 groups according to the history of chronic alcoholic intake ( n = 25 each): control group (alcoholic intake per day ＜ 25 g) and chronic alcoholic group (alcoholic intake per day＞45 g, lasting for 2 yr or more). The EC50 and 95% confidence interval (CI)were determined by up-and-down sequential method. The initial target effect-site concentration was 2 μg/nl in chronic alcoholic group and 1.5μg/ml in control group, and the ratio between the two successive concentrations was 1.05. Loss of consciousness was defined as loss of response to verbal command and eyelash stimulation. Results The EC50 of propofol that produced loss of consciousness was 3.92 (95 % CI 3.56-4.63 ) μg/ml in chronic alcoholic group and 2.73 (95%CI 2.26-3.31)μg/ml in control group. The EC50 of propofol was significantly higher in chronic alcoholic group than in control group ( P ＜ 0.05). Conclusion Chronic alcohol intake can increase the EC50 of propofol required to induce loss of consciousness and reduce sedative potency in patients. Key words: Alcohol drinking; Propofol; Dose-response relationship, drug; Drug delivery system