抄録
Although a two-compartment model represents an adequate model for a reasonably sophisticated description of the time course of many drugs in the body, the still simpler one-compartment model provides certain pharmacokinetic parameters which are useful, particularly in clinical application. A single-compartment approximation may be made under certain conditions by omitting blood level data in the period shortly after rapid intravenous administration. Pharmacokinetic calculations utilizing the parameters from this approximation were compared with those based on the true two-compartment model. Simple equations were developed to test the validity of the single-compartment approximation. Errors in the calculated values based on the single-compartment approximation were expressed in terms of the smaller exponent β and ratios (m=A/B and n-α/β) of the coefficients and the exponents from biexponential fitting to blood level data after rapid intravenous administration. It was shown that the single-compartment approximation may or may not be satisfactorily used for clinical purposes depending upon size of m and n or relative size of m and n. Using the formulas derived in this report and data from intravenous administration on a few patients, it is possible to determine for a particular drug whether the one-compartment model is an adequately approximate model for clinical purposes, or whether the two-compartment model is really necessary.
