Objective This study was to observe the neuromuscular blocking effects, histamine release and haemodynamic changes of different
doses of domestic vecuronium in the induction of general anesthesia. Methods 42 ASA Ⅰ～Ⅱ patients undergoing elective surgery were divided into 3 groups (14 patients, each). After induction of anesthesia, a single bolus of domestic vecuronium 0.1mg/kg, 0.2 mg/kg, or atracurium 0.5mg/kg was administered to the 3 groups of patients respectively. The onset time, maximum block effect and condition of intubation were recorded. Venous blood samples were obtained before and at 2 and 5 min after the administration of the relaxant for determination of plasma histamine concentrations using fluorometry. The haemodynamical changes before and 1 ～ 5min after administration of the relaxant were also recorded. Results The onset time after administration of vecuronium 0.2mg/kg was significantly shorter than that of vecuronium 0.1 mg/kg (P< 0.05). The plasma histamine concentration and haemodynamical changes before and after administration of the relaxant had no significant differences in 3 groups (P>0.05). Conclusion Domestic vecuronium does not affect plasma histamine concentration and haemodynamics. 0.1mg/kg and 0.2mg/kg domestic vecuronium can be safely used in the induction of general anesthesia with satisfactory neuromuscular blocking effects.