I have a PKPD model with Vehicle or different drug dosages. there is a clear vehicle effect in the data I need to take into account. The effects are in time after dosing but the same subjects were dosed with both vehicle or drug on different occasions. I would like to analyse the data using TAD instead of time. However, when I set the dose to zero for my vehicle dosing it is not recognised as a dose so the TAD analysis fail. How do I set a Vehicle dose so that the time resets after vehicle dosing?
BR Frederik