Dear NONMEM users, I encountered the following problem in my NONMEM fitting:
I have data from 3 dogs receiving i.v infusion of a certain drug. For each dog I have around 15 "time-concentration" pairs. What I am trying to do with the data is to use NONMEM to fit them and estimate PK parameters with ADVAN3 and TRANS4. For each PK parameter I am trying to estimate OMEGA. However I could not do the modeling successfully unless I fix 0 for Q and V2 in OMEGA. Why is this happening? Is it reasonable to assume 0 inter-subject variation for Q and V2 in my case? Thanks a lot.
