Pipecuronium bromide is a long-acting steroidal neuromuscular blocking drug. This study was designed to evaluate the neuromuscular-blocking action and the cardiovascular effects of pipecuronium in patients under O2-N2 O-enflurane anesthesia, by comparing with those of pancuronium and vecuronium.

Fifty-one adult patients (ASA class 1 or 2) were randomly received pipecuronium 0.1 mg/kg (n=17), pancuronium 0.12 mg/kg (n=17), or vecuronium 0.1 mg/kg (n=l7) as a single intravenous bolus dose. Anesthesia was induced with thiopental 5 mg/kg, followed by one of the muscle relaxants. Patients were then given O2 (2 L/min) - N2O(2 L/min)-enflurane(1.8 vol%) by face mask. Trachea was intubated, and anesthesia was maintained with O2 (2 L/min)- N2O(2 L/min)-enflurane(1-2.5 vol%) during whole study period. Neuromuscular blocking effect was assessed by response of the adductor pollicis muscle in 2Hz train-of-four(TOF) stimulation of ulnar nerve every 20 seconds. The times from administration of initial dose to loss and reappearance of four twitches to TOF were measured. Systolic and diastolic blood pressure(SAP,DAP) and heart rate(HR) were noninvasively measured.

The onset times of pipecuronium, pancuronium, and vecuronium were 278±99, 268±67, and 208±56 seconds, respectively. The duration of action of pipecuronium, pancuronium, and vecuronium were 148±99, 145±35, and 52±12 minutes, respectively. SAP and DAP with pancuronium were significantly greater than those with pipecuronium or vecuronium I minute after the administration. No significant difference in SAP and DAP was found until 5 minutes after the administration among the agents. HR was increased significantly until 20 minutes after the administration of pancuronium.

Pipecuronium is a long-acting drug suitable for longer operations in which cardiovascular stability is required.