..have single dose plasma concentrations and I want to fit them to a one compartment model with a lagtime with a view to performing a multiple dose simulation.
The plasma concentration time worksheet was imported and connected to the PK MODEL OBJECT.
I have fitted plasma concentration time data to a 1 cpt model with first order absorption and first order elimination with a lagtime. I used initial estimates and I got the program to provide the fit and the parameters I need for a multiple dose simulation.
I have disconnected the original worksheet with the plasma concentration time (from the single dose) from the NCA object.[ is this a blunder?].
I have the multiple dose Table imported as a worksheet and I have used this worksheet for pointing (CONNECTING) to the dose for the NCA model object. The doses are set correctly to ng.
I have also imported a new Table of Times I want the simulations to be made at. This is a column of time (x values) in hours.
Now for the simulations I have eliminated the lagtime and set the modet to run as a 1 cpt model first order elimination and first order absorption.
I find that the simulation runs and it uses the times I want but the values of y (should be ng) are ridiculously high. The pattern of the predicted profile for the multiple doses (y axis) is correct , but the scale is absurd and I do not know why.
I have seen this problem before, but I cannot remember what the cause is. I have checked the doses and the units are ok (ng). I am baffled since this is so routine and yet I cannot get it to work.
Please can be advised accordingly,