Safety and efficacy of atracurium (BW33A) in surgical patients receiving balanced or isoflurane anesthesia.

Atracurium was administered in a dose range of 0.027-0.4 mg/kg and dose-response curves were established for both balanced and isoflurane anesthetic techniques. With balanced anesthesia, ED50 and ED95 were 0.12 and 0.27 mg/kg, respectively, while with isoflurane they were 0.07 and 0.13 mg/kg and the least-squares regression line R2 values were 0.71 and 0.64, respectively. With balanced anesthesia there was a significant increase in systolic blood pressure at the 0.04 mg/kg dose (P = 0.02), while with isoflurane the systolic and diastolic blood pressures decreased at the 0.3 mg/kg dose (P less than 0.03). These changes were clinically insignificant. Atracurium is a potent nondepolarizing muscle relaxant which is potentiated by isoflurane. Its cardiovascular effects appear clinically nonsignificant. There is no evidence of histamine release.