Influences of age and gender on dose response and time course of effect ofatracurium in anesthetized adult patients

Study Objective: To determine the influences of age and gender on the dose response anti the time course of effect of atracurium. Design: Prospective, nonrandomized, clinical comparison. Setting: Operating room, Plastic Surgery Hospital of the Chinese Academy of Medical Sciences and Peking Union Medical College. Patients: 72 adult ASA physical status I patients (38 mule and 34 female), aged 15 to 59 years, scheduled for elective plastic surgery. Interventions: Patients were divided into the three groups on the basis of age: Group 1, patients aged 15-29 years (n = 32); Group 2, patients aged 30 -40 years (n = 21); and Group 3, patients aged 41-59 years (n = 19). Anesth esia was maintained with 60% nitrous oxide in oxygen, thiopental, and incre mental doses of fentanyl,1 as required. The dose-response relationship of a tracurium was determined by a cumulative dose-response technique. Measurements and Main Results: Neuromuscular function was assessed mechanom yo-graphically with train-of-four stimulation at the wrist every 12 seconds and the percentage depression of first twitch (T-1) response was used as t he study variable. Age and gender significantly affected the dose-response relationship and time course of recovery of atracurium. Advancing age was a ssociated with a reduced effective doses (ED,, ED,, and ED95) of atracurium and a longer duration of action. The effective doses of atracurium were gr eater, and its duration of action was shower in men than in women. There we re significant differences in the 50 %, 90 %, and 95 % effective dose (ED50 , ED90, and ED95) of atracurium, and clinical duration and total duration f ollowing administration, of atracurium 400 mu g/hg among the three age grou ps, and between men and women. Conclusions: Age and gender have significant effects on the dose response a nd time course of effect of atracurium. Cider patients and women ala mora s ensitive to atracurium-induced neuromuscular block than are young patients and men. (C) 1999 by Elsevier Science Inc.