The closed chamber technique - uptake, endogenous production, excretion, steady-state kinetics and rates of metabolism of gases and vapors

The "closed chamber technique" (CCT) is presented. It allows investigation of pharmacokinetics of volatile substances in vivo in animals and in man and in vitro using tissue fractions. During the exposure period only the atmospheric concentrations of the substance are measured. The concentration-time data obtained are pharmacokinetically analyzed by a two compartment model describing uptake, endogenous production and excretion of the unchanged substance and its metabolic elimination. Using this model, pharmacokinetics of ethylene have been determined in rats and man. For both species, the results compared well with an estimation based on an allometric species scaling. Furthermore, the applicability of CCT is demonstrated in vivo on several other gases and vapors of solvents, e.g. trichloroethylene and 1,1,1-trichloroethane, and in vitro on 1,2-epoxybutene-3.