Fazadinium and pancuronium: a pharmacodynamic study.

The neuromuscular blocking characteristics of fazadinium and pancuronium were compared using a general pharmacodynamic model. Since it characterizes the overall relationship between dose and effect, the model can be used to determine precisely equipotent doses, compare time-effect curves, and reconcile the apparently inconsistent clinical and pharmacokinetic characteristics of the two drugs. Fazadinium was shown to have a shorter duration than pancuronium, and appeared to exhibit less variation between subjects. The potency ratio varied between 3.4 : 1 and 7.2 : 1, depending upon the definition chosen. A general solution for the three-compartment open mammillary model, following any set of initial conditions if presented as an appendix. These equations allow explicit computation of any pattern of drug incrementation into any compartment of the model.