Bioequivalence and Bioavailability Forum

Hi, I just downloaded the Monolix software and I want to build a pharmacokinetic model for methotrexate, but I am not familiar with using Monolix software, so can anyone point me a direction where I should look into?
So, what I want to do here is:
Methotrexate is activated into methotrexate polyglutamate form inside the red blood cells. I want to see if patients were on parenteral form (especially subcutaneous route) of methotrexate, and they have achieved steady state (I mean steady state of methotrexate polyglutamate inside the red blood cells). What I am trying to find out here is: I want to build a PK model to simulate if the patient skip a dose of parenteral methotrexate, how does it affect the concentration of methotrexate polyglutamate inside the red blood cells.

I hope anyone could help me with this, even if it is just a rough guide, it will be really appreciated. Thanks in advance.

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Edit: Category changed; see also this post #1. [Helmut]