Hi, I am performing Noncompartmental Pharmacokinetics in SAS version 9.4 and for that this paper is really very useful. http://www.lexjansen.com/pharmasug/2005/statisticspharmacokinetics/sp07.pdf File required for NCA contains subjectID, Treatment, Time and concentration data. Generally, terminal elimination constant is calculated from the linear regression of concentration vs. time curve using the least square regression method. For that minimum three points is neded to define the terminal (log-linear) portion of the curve and the selection is based on the best adjusted square coeffiecient of regression (r2). How can we plot that regression line during the linear phase of the concentration vs. time data to estimate the terminal elimination rate constant (lambda z) using best fit method? How SAS automatically select number of required data points to calculate r2 and draw line to connect that specific points only ? The desired output has been attached for reference.
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