Tutorial: Simplified Absorption

This tutorial explores the use of a simple oral absorption rate constant and time lag instead of the Advanced Compartmental and Transit (ACAT) oral absorption model.

1. Open GPX™ and, in the Dashboard view, click on the icon next to New to create a new project.

2. Type in the Project Name “Simplified absorption” and via Browse navigate to/add a folder to save the project.

3. Click on Create.

4. Click on the Compounds view.

5. Click on Add.

6. Type "Drug" then click on OK (or press Enter). Use all of the default compound properties.

7. Save the project, using the Save button in the top right-hand corner of the interface and click on OK in the Save completed message window.

8. Click on the Dosing view.

9. Expand the Formulations panel.

10. Click on Add.

11. Type "Simplified" then click on OK (or press enter) and then select SimplifiedDose from the Route drop-down list.

12. Expand the Dosing Schedules panel.

13. Click on Add.

14. Type "100mg Simplified Dose" then click on OK (or press Enter).

15. Save the project and click on OK.

16. Click on the Physiologies view.

17. Click on Add.

18. Type "Human" and ensure that Human is selected as species, then click on OK (or press Enter).

19. Save the project and click on OK.

20. Click on the Pharmacokinetics view and expand the Compartmental panel and then decrease the General Clearance to 0.2 L/h/kg.

21. Save the project and click on OK.

22. Click on the Simulations view.

23. Click on Add.

24. Type "100mg Simplified Dose Human" then click on OK (or press Enter).

25. Expand the Drug Administration panel to see that there are no Dose Number, Absorption Number or Dissolution Number displayed.

26. Switch the Gastrointestinal Model to Simplified via the drop-down list.

27. Expand the Compound Settings panel and then expand the Simplified Absorption sub-panel. Enter a Ka of 1.25 1/h and a Time lag of 0.5 h.

28. Save the project and click on OK.

29. Click on Check Warnings and then Run Simulation (both buttons are found at the top of the Simulations view).

30. In the Analysis view notice the time lag in the C_p-Time profile.

31. In the Analysis view click on the Absorption & Dissolution plot in the Key View ribbon to see that the plot is blank as no ACAT model was included in the simulation.

32. In the Analysis view click on the Regional Absorption plot in the Key View ribbon to see that the plot is blank as no ACAT model was included in the simulation.

33. To explore the absorption, switch the Analysis Mode from Key View to Deep View

34. In the Deep View panel type "simp" into the Search box above the Series List tree and press Enter, then select Simplified Dose under Mass and Total under Rate. Under the tree, select Mass Absorbed and while holding Ctrl click on Net Ka.