Clinical pharmacokinetics of cisatracurium

Objective This study was designed to determine the clinical pharmacokinetics of cisatracurium in Chinese patients. The purpose of this study was twofold: the determination of ED50 and ED95 of cisatracurium and the intubating conditions and changes in BP and HR produced by 2×ED95 and 3 ×ED95 . Methods 100 patients scheduled for elective surgery, aged 30-65 years, served as the experimental subjects. Anesthesia was induced with propofol 2mg/kg and fentanyl 4μg/kg. 5 min after BP and HR were stabilized the study was started. The study consisted of two parts according to the purpose of the study. In part Ⅰ 70 patients were included and randomized to 7 groups based on the doses of cisatracurium the patients received. The doses were 25, 30, 35, 40, 45, 50 and 55 μg/kg from group Ⅰ to Ⅶ. Neuromuscular transmission was assessed by measuring the responses of adductor pollicis muscle to stimulation of ulnar nerve with TOF pulses. The maximal depression of Tt was measured after administration of cisrtracurium, and ED50 and ED95 were calculated. In part Ⅱ 30 patients were included and divided into two groups to receive 2×ED95 (group Ⅷ ) or 3×ED95 (group Ⅸ ) of cisatracurium. The intubating conditions were evaluated. The onset time and time of recovery from paralysis as well as the changes in BP and HR after administration of cisatracurium were recorded. Results ED50 and ED95 for cisatracurium were 30.7μg/kg and 53.4μg/kg respectively. The onset times for 2×ED95 and 3×ED95 were (254±84)s and (190±59)s. The durations of action was (38.8±6.1)min and (53.2 8.8)min respectively. Recovery indexes were (16.4±4.9) min and (15.6±5.2) min. There were little changes in BP and HR after administration of cisatracurium in both group Ⅷ and Ⅸ. The intubating conditions were not significantly different. Conclusions ED50 and ED95 for cisatracurium are 30.7μg/kg and 53.4μg/kg in Chinese patients. The onset time is shorter and duration of action longer with 3×ED95 which does not significantly affect BP and HR.