Use of atracurium or vecuronium to prolong the action of tubocurarine

Comparison of vecuronium with ORG 9487 and their interaction

PURPOSE

To compare the pharmacodynamic behaviour of vecuronium with that of ORG 9487, we measured the time-course of action of equipotent doses of ORG 9487 and vecuronium and investigated their mutual interaction when given in succession.

METHODS

Sixty ASA I-II patients were anaesthetized with thiopentone, fentanyl, halothane and nitrous oxide and assigned randomly to four groups. Each patient received an initial dose (ID) of either vecuronium (V) or ORG 9487 (O) followed by maintenance doses (MDn) of either V or O (ID/MD: O/O, V/O, O/V, and V/V). The time course of action was measured mechanomyographically, determining the duration until 25% recovery of the single twitch (DUR25).

RESULTS

The onset time of an ID of ORG 9487 was shorter than that of an ID of vecuronium (96 vs 203 sec, P < 0.001). The DUR25 of the ID of ORG 9487 was less than half that of vecuronium (10.7 +/- 2.8 vs 28.8 +/- 6.1 min, P < 0.001). The DUR25 of MD1 and MD2 of ORG 9487 were shorter than those of vecuronium (O/O: 7.3 +/- 2.8 and 8.5 +/- 2.4 min; V/O: 12.7 +/- 3.3 and 11.5 +/- 3.5 min, vs O/V: 16.4 +/- 4.5 and 20.6 +/- 4.7 min; V/V: 18.8 +/- 3.0 and 20.1 +/- 3.8 min, respectively, P < 0.05). AN ID of vecuronium prolonged the DUR25 of MD1 and MD2 of ORG 9487 (P < 0.05).

CONCLUSION

ORG 9487 is a muscle relaxant with a shorter duration of action than vecuronium. Maintenance doses of ORG 9487 are also shorter acting than roughly equipotent maintenance doses of vecuronium, irrespective of which relaxant is given initially.

Interactions between mivacurium, rocuronium, and vecuronium during general anesthesia

This study was designed to examine the interactions between mivacurium and rocuronium or vecuronium when administered during a standardized anesthetic technique. Seventy healthy women undergoing abdominal hysterectomy procedures with a standardized thiopental-sufentanil-desflurane-nitrous oxide anesthetic technique were randomly assigned to one of seven treatment groups (10 patients each). After a tracheal intubating dose of vecuronium 100 micrograms/kg (Groups 1 and 2), rocuronium 600 micrograms/kg (Groups 3 and 4), or mivacurium 250 micrograms/kg (Groups 5, 6, and 7), patients received vecuronium, 25 micrograms/kg (Groups 1 and 6), rocuronium 150 micrograms/kg (Groups 3 and 7), or mivacurium 50 micrograms/kg (Groups 2, 4, and 5) for maintenance of neuromuscular blockade. Neuromuscular function was assessed using electromyography, with a train-of-four mode of stimulation at the wrist every 10 s. The clinical duration (time for T1 to return to 25% of baseline) of the maintenance dose of mivacurium was significantly longer after an intubating dose of rocuronium (40 +/- 8 min) and vecuronium (28 +/- 6 min) than after mivacurium (12 +/- 3 min). The clinical duration of maintenance doses of vecuronium (18 +/- 6 min) and rocuronium (13 +/- 2 min) were significantly shorter after an intubating dose of mivacurium than that after an intubating dose of vecuronium (30 +/- 5 min) or rocuronium (42 +/- 12 min), respectively. These data suggest that with consecutive administration of neuromuscular blocking drugs, the initial duration of action depends more on the kinetics of the first neuromuscular blocking drug than the subsequent drug. Thus, there appears to be no clinical advantage in using mivacurium for maintenance of neuromuscular blockade after initial administration of rocuronium or vecuronium.

Recovery of neuromuscular function after atracurium and pancuronium maintenance of pancuronium block

The study was undertaken to determine whether a neuromuscular blockade induced with pancuronium but maintained with atracurium was associated with a shorter time to complete recovery after administration of neostigmine than if the blockade was maintained with pancuronium alone. Anaesthesia consisted of thiopentone, N2O/O2/enflurane and fentanyl, and the neuromuscular blockade, induced by pancuronium 0.1 mg.kg-1 was monitored by the force of contraction of adductor pollicis during major abdominal surgery lasting 2-5 hr. In 24 patients--Group 1--atracurium 0.07 mg.kg-1 was repeated when the first twitch of the train-of-four (TOF) returned to 25% of control (T1/TC 25). In 28 patients--Group 2--pancuronium 0.015 mg.kg-1 was given at similar recovery of T1/TC. At the end of surgery, neostigmine 0.07 mg.kg-1 and glycopyrolate 0.015 mg.kg-1 were given to reverse the residual neuromuscular blockade which was indicated by a T1/TC of less than 25% in all patients. The time from injection of the reversal drugs to a TOF ratio of 70% was similar in both groups (Group 1, 11.6 +/- 7.6 min; Group 2, 10.1 +/- 6 min; P = NS), but the recovery index was smaller in Group 2 (Group 1, 4 +/- 2.6 min; Group 2, 2.61 +/- 1.2 min; P < 0.05). Furthermore, there was no difference between groups in the duration of action of each redose. The study showed that when compared with pancuronium, equipotent doses of atracurium were not associated with (a) a shorter time to complete recovery from a neuromuscular blockade induced with pancuronium or (b) a shorter duration of action.

Extending a pipecuronium neuromuscular block. Increments of atracurium or vecuronium as an alternative to pipecuronium

Ten patients received increasing doses of pipecuronium at induction of anaesthesia. A dose response relationship was then constructed from which ED90 and ED95 values were measured as 43.4 micrograms.kg-1 and 50.5 micrograms.kg-1 respectively. A further 30 patients received pipecuronium in a dose sufficient to produce greater than 90% neuromuscular block. When the first contraction of the train-of-four had returned to 10% of control, a small increment of atracurium (1.1 mg), vercuronium (0.25 mg) or pipecuronium (0.21 mg) was administered, and this was repeated subsequently using the same criterion of recovery on each occasion. The duration and intensity of the block with pipecuronium increments remained constant. The duration of the block following atracurium or vecuronium was progressively less with subsequent increments until steady state was reached. The final mean durations at steady state were pipecuronium 7.37 min, atracurium 6.99 min, and vecuronium 5.15 min.