Potency and hourly maintenance requirement of combinations of mivacurium and pancuronium in adults

Purpose

To evaluate the dose-response and maintenance requirements of a combination of mivacurium and pancuronium (cMP) in clinical practice.

Methods

In a randomised, open clinical study, 70 patients, 17–50 yr of age, were anaesthetised with propofol, alfentanil and nitrous oxide in oxygen. Thirty patients received mivacurium and 20 patients received pancuronium to establish dose-response curves for these agents. Hourly maintenance requirements of mivacurium and pancuronium to maintain 90–95% neuromuscular blockade (NMB) were determined. Thereafter, 20 additional patients received cMP in incremental doses to establish a cumulative dose-response curve for cMP followed by maintenance doses of cMP NMB was recorded by adductor pollicis electromyography.

Results

The ED₉₅ values for mivacurium and pancuronium were 100 and 66μg·kg^?1, respectively; and for the cMP 2:1 (in mg:mg basis), 32 μg·kg^?1 mivacurium together with 16 μg·kg^?1 pancuronium. This cMP was 1.8 times more potent than one parent agent (P < 0.0001 ). When cMP 2:1 was used, 60% of normal maintenance requirement of pancuronium reduced the requirement of mivacurium by > 90%. If cMP 20:1 was used, then 20% of normal maintenance requirement of pancuronium reduced the requirement of mivacurium by > 70%. Neostigmine 35 μg·kKg^?1 given at T₁ 10% recovery following cMP reversed the NMB to a TOF ratio of 0.70 in 9.5 ±3.9 min.

Conclusion

These results reflect considerable synergism between mivacurium and pancuronium. The cMP is near intermediate-acting and the NMB is easily reversed with neostigmine. By using cMR it may be possible to save some pharmacological costs during maintenance of anaesthesia.