Pulmonary absorption and excretion of compounds in the gas phase: theoretical pharmacokinetic and toxicokinetic analysis.
Kinetic equations were derived that describe the plasma concentration of an inhaled compound during and following single or repeated regular and irregular pulmonary exposures. The equations are based on a diffusional type of input function and assume a linear disposition with a biexponential unit-impulse response. The use of linear system analysis avoids the complexity of modeling the disposition processes; yet, the effect of these processes is still accounted for mathematically. The approach, therefore, appears to be more general and rational than approaches based on linear compartmental modeling. The ways in which the kinetic equations can be readily applied in pharmacokinetic or toxicokinetic analyses to obtain valuable parameters that enable kinetic predictions of the cumulation during prolonged exposure are discussed. The toxicokinetic problem of comparing the effect of different work schedules in occupational environments with air contaminants is discussed. Formulas derived from considerations of the blood plasma kinetics are presented for the calculation of an adjustment factor for the adjustment of the contaminant threshold limit value for abnormal work weeks. The use of these formulas appears to be more rational than that of similar formulas that have been proposed.
D000042:Absorption; D000395:Air Pollutants, Occupational / Q000009:adverse effects / Q000032:analysis*; D005740:Gases; D006801:Humans; D007700:Kinetics; D008168:Lung / Q000378:metabolism*; D008452:Maximum Allowable Concentration; D008954:Models, Biological
D000395:Air Pollutants, Occupational; D005740:Gases