Effects of succinylcholine on the pharmacodynamics of pipecuronium and pancuronium

Effect of succinylcholine on subsequently administered mivacurium in children

The interaction between mivacurium and succinylcholine when mivacurium was administered during the early recovery from succinylcholine block was studied in 30 children 2-12 years of age anaesthetized with propofolalfentanil-N2O-O2. Neuromuscular response was monitored by adductor pollicis EMG. Fifteen patients received 200 micrograms.kg-1 of mivacurium (Group M), and another fifteen received 1500 micrograms.kg-1 of succinylcholine followed by 200 micrograms.kg-1 of mivacurium when the first EMG response recovered to 5% of calibration value (Group SchM). Plasma cholinesterase (pChE) activity was normal in each patient. The recovery times following mivacurium did not differ between the two groups. Times required for recovery of the first EMG response from 25 to 75% of full EMG recovery were 3.6 +/- 1.0 (mean +/- SD) and 4.0 +/- 0.7 min for the Groups M and SchM, respectively. The time from administration of mivacurium to the recovery of train-of-four ratio 0.70 was 13.2 +/- 3.3 min for the Group M and 13.6 +/- 3.1 min for the Group SchM (NS). Thus, in patients with normal pChE activity preceding administration of succinylcholine did not influence the recovery of neuromuscular function from subsequent mivacurium.

Pharmacodynamics of rocuronium with and without prior administration of succinylcholine

STUDY OBJECTIVES

To compare succinylcholine (S) and rocuronium (R) used for endotracheal intubation, and to assess the possible action of S on subsequently administered R.

DESIGN

Double-blind, randomized, phase III study.

SETTING

University Medical Center.

PATIENTS

24 ASA physical status I and II patients, ages 28 to 65, undergoing general anesthesia for abdominal procedures.

INTERVENTION

Double-blind administration of R 600 mcg/kg (Group A) or S 1 mg/kg was achieved with open label R 150 mcg/kg. Standardized general anesthetic technique with sodium thiopental, fentanyl, and nitrous oxide in oxygen was administered.

MEASUREMENTS AND MAIN RESULTS

Neuromuscular junction was tested by ulnar nerve stimulation and mechanomyograph. Intubation was attempted at 80% first twitch depression of train-of-four. Heart rate and blood pressure were recorded throughout. Onset times were 74 +/- 37 seconds for S and 130 +/- 46 seconds for R. Intubation times were 76 +/- 29 seconds for S and 85 +/- 23 seconds for R (no significant difference). Good to excellent intubation conditions were achieved in both groups. S given prior to R decreased onset time and increased duration of R, when compared with R given alone. No drug related cardiovascular events were noted.

CONCLUSION

Rapid intubation conditions can be obtained after both S and R. Given its overall safety profile, R can be used when S is contraindicated, or in healthy patients with no apparent difficult airway, when procedures are expected to last more than 25 minutes.

Effect of prior administration of succinylcholine on duration of action of vecuronium during enflurane anaesthesia

The effects of succinylcholine, which was given to facilitate tracheal intubation on the duration of action of subsequently administered vecuronium bromide, were evaluated in 54 adult patients who underwent abdominal surgeries under enflurane anaesthesia. The electromyographic response to train-of-four ulnar nerve stimulation was measured. Twenty-seven patients received 1 mg.kg-1 of succinylcholine, followed by 0.15 mg.kg-1 of vecuronium when the electromyographic response recovered to 50% of control after succinylcholine-induced neuromuscular blockade. The other 27 patients served as the control group, receiving 0.15 mg.kg-1 of vecuronium without prior administration of succinylcholine. In both groups, administration of supplemental 0.04 mg.kg-1 of vecuronium was repeated whenever the electromyographic response recovered to 25% of control during surgical procedures. The duration of blockade induced by the initial 0.15 mg.kg-1 of vecuronium was 56.5 +/- 12.8 (mean +/- s.d.) min for the group with succinylcholine, and 58.5 +/- 21.5 min for the control group. In both groups, the average duration of four consecutive supplemental doses of vecuronium was approximately 35 min. No significant differences between groups were found in the duration of neuromuscular blockade induced by initial and supplemental doses of vecuronium.

Neuromuscular effects of pipecuronium during sevoflurane anesthesia compared with isoflurane and enflurane anesthesia

We evaluated the neuromuscular effects of pipecuronium during anesthesia with equipotent concentrations of either sevoflurane, isoflurane or enflurane. Twenty-seven patients scheduled for minor elective otolaryngeal or plastic surgery were studied and randomly assigned to 3 groups, one group per anesthetic agent. Anesthesia was induced with thiamylal 5 mg.kg(-1) and the trachea was intubated with succinylcholine 1 mg.kg(-1), then anesthesia was maintained with 60% nitrous oxide in oxygen and sevolfurane, isoflurane or enflurane, depending on the group. Neuromuscular blocking effects were monitored by recording the electromyographic activity of the adductor pollicis muscle from supramaximal stimulation of the ulnar nerve at 10-s intervals. Pipecuronium 40 microg.kg(-1) was administered when electromyographic activity had reached a stable state, 30 min after succinylcholine administration. The maximum effect (% block of control) and clinical duration (time to 25% recovery) of pipecuronium were 99.1 +/- 1.4% and 63.7 +/- 14.7 min (mean +/- S.D.) for sevoflurane, 99.0 +/- 2.0% and 60.9 +/- 20.5 min for isoflurane, and 98.0 +/- 2.5% and 62.8 +/- 28.7 min for enflurane, respectively. There were no significant differences in these values between the anesthetics. Cardiovascular stimulant effects were not observed in any of the groups. We conclude that the effect of pipecuronium under seveflurane anesthesia is similar to that under isoflurane and enflurane anesthesia.

Newer neuromuscular blocking drugs. An overview of their clinical pharmacology and therapeutic use

Four new nondepolarising muscle relaxants, pipecuronium bromide, doxacurium chloride, mivacurium chloride and Org 9426 (rocuronium) offer alternatives to the established agents atracurium besilate and vecuronium bromide. Pipecuronium and Org 9426 are steroidal compounds, the latter being a monoquaternary agent, whereas doxacurium and mivacurium are bisquaternary benzylisoquinolinium compounds. Pipecuronium and doxacurium have a relatively slow onset and a long duration of action. Pipecuronium produces maximum block in 3 to 6 min when given in a dose of 45 to 80 micrograms/kg, and a duration of clinical relaxation of between 40 and 110 min. Doxacurium is more potent, but is the least rapid and the longest acting relaxant currently available. When administered in doses of 37 to 80 micrograms/kg, it produces maximum block within 3.5 to 10 min, with a duration of clinical relaxation of 77 to 164 min. The advantage of both pipecuronium and doxacurium is their cardiovascular stability. Both agents are primarily eliminated via the kidneys and both have now been licensed for use in the US. Mivacurium is a muscle relaxant with a short duration of action. When administered in doses of 0.1 to 0.25 mg/kg it produces maximum block in 2 to 4 min, but the duration of clinical relaxation is less than 20 min. Higher doses which could induce a faster neuromuscular block are unfortunately associated with some histamine liberation. The drug is metabolised by plasma cholinesterase. Mivacurium has also been licensed for use in the US. Org 9426 is an agent with a rapid onset but an intermediate duration of action. A dose of 0.5 to 0.6 mg/kg induces maximum block in about 1.5 min and has a duration of clinical relaxation of about 30 min. The rapid onset of effect could be useful for early intubation as an alternative to suxamethonium chloride. However, much more clinical experience is needed with this agent, particularly with regard to duration of action of larger doses and occurrence of side effects. The drug is mainly eliminated via the liver.