Unique approach for calculation of first-order absorption rate constants from blood or urine data
C. Pidgeon, W. Pitlick
Apr 1, 1980
Citations
3
Citations
Journal
Journal of Pharmacokinetics and Biopharmaceutics
Full text
Semantic Scholar
Key Takeaway Key Takeaway: This method for calculating first-order absorption rate constants from blood or urine data reduces the need for large numbers of samples and is less influenced by errors in data points prior to maximum concentration or excretion rate.
Abstract
Several methods are employed to estimate an apparent first-order rate constant for absorption in a one-compartment model. A method for calculation of the absorption rate constant (Ka)has been derived based on the area under the concentration-time curve for blood data or the area under the excretion rate-time curve for urine data between the observed time of maximum concentration or rate (tmax)and the maximum concentration (Cmax)or maximum rate of excretion (Xumax).The method obviates the need for large numbers of samples in the absorptive phase. The method also avoids extensive calculations and is less influenced by errors in data points prior to Cmaxor Xu max,where the rate of change is rapid and error is likely. The methods have been tested on theoretical data with and without error generated using a range of values for Kaand elimination rate constants (KE).Errors in the estimate of Kaare proportional to error in the data. The method compares favorably with nonlinear regression analysis.