I have setup a 2 compartment population PK (first order conditional estimation method)model for plasma concentration that seems to fit the data well by diagnostics.
However, recently I did obtain some tissue (liver concentration) data that I would like to fit the tissue observations into the model.
I imagine the new model to be a 3 compartment fit. central (plasma), secondary (liver), and peripheral, but have not been successful using the graphical interface to get any decent fit with tissue (liver observations) included.
I know it is a first order absorption from SC injection site to plasma (central), first order distribution between central and peripheral (Q3) like the intercompartment clearance, michaelis-menten uptake to liver from plasma (Q4), first order elimination from plasma (CLp) and liver (Clliv), like the uptake rate from plasma to liver.
Could you please assist with my model, I have the link below.