Some methods for estimating absorption rate constant of linear one-compartment open models

Abstract

In previous reports methods of estimating absorption rate constant of linear one-compartment open models from peak blood level or peak urinary excretion rate and post-absorptive data have been given (Pidgeon and Pitlick, 1977, 1980; BarzegarJalali, 1982a). However, since it is unlikely that the peak values can be observed exactly experimentally. the absorption rate constant obtained from these methods might therefore not be accurate. In this communication, the parallel line method (Batzegar-Jalali, 1982b) will bc applied to the linear one-compartment open models (without or with lag time in absorption) to derive equations from which the absorption rate constant can be estimated from a single data point (for the model without lag time) or two data points (for the model with lag time) at the absorptive phase and postabsorptive data using blood or urine data. Some of the equations can also be employed for graphical determination of the rate constant. Details of the derivation of the equations are as follows. (1) The model without /ug time in absorption. The blood level curve for the model is described by Eqn. 1 (Gibaldi and Perrier, 1975)