Intestinal permeability (transcellular) giving different PK profiles depending on input type

[DR-99]

Hello,

According to the help summary for the parameter "Intestinal permeability (transcellular)", the formula is 10^(m*log10(Specific intestinal permeability (transcellular))+b). I would like this value to be two orders of magnitude larger than my specific intestinal permeability, so initially I have been manually overriding the value in the corresponding field for my simulations. However, to perform pop simulations, I have decided to use the equation and began adjusting b to 2 to account for a similar higher intestinal permeability. I can visually confirm that the calculated value is correct, however my PK profiles are largely different, with the latter method resulting in significantly reduced absorption. I have looked over the other permeability values (eg. P (BC>PLS), etc.) and they do not seem to be affected by the manipulation. Can someone please shed light on this discrepancy? It seems that manually overriding the value directly is affecting more parameters than using the built-in equation, but it is unclear what these parameters are.