A physiologically based mathematical model for the human inhalation pharmacokinetics of...

A physiologically based mathematical model is described for the human inhalation pharmacokinetics of 1,1,2-trichloro-1,2,2-trifluoroethane (FC113). Physiological parameters for the model are derived from the scientific literature. Partition coefficients are determined from in vitro measurements. Predictions of the resulting model for breath and blood concentrations compare well with results of a human volunteer study described in a companion paper (Woollen et al. 1990). Using this data some alternative models are also examined with different choices of physiological parameters and partition coefficients. The mathematical model is used to examine the consequences of metabolic elimination of FC113. A value for metabolic clearance is estimated using the during-exposure breath concentration data; however, the concentrations of FC113 in breath or blood during and after exposure are shown to be insensitive to metabolic clearance. Consequently, no firm conclusion can yet be drawn as to whether FC113 is metabolised by man.