• Use the menu Plot to plot the PK profile, modify the PK model, the PK parameters, the dosage regimen and the design of the output.

• Use the menu Table to create and save a table with the concentration values.

• Use the menu Codes to display and download the Simulx R code pkmodelCode.R automatically generated using the current settings, the ui.R and server.R files used for this application.

Select the administration route and the dosage regimen in the menu Administration:

• iv bolus, iv infusion, or oral administration,
• time of first dose,
• number of doses,
• interdose interval,
• amount.
• infusion time (only for infusion),

Select the parameterization in the menu Parameterization:

• rate constants (\(k\), \(k_{12}\), \(k_{21}\), \(k_{13}\), \(k_{31}\)),
• clearances (\(Cl\), \(Q_{2}\), \(V_{2}\), \(Q_{3}\), \(V_{3}\)),

Define the PK model in the menu Model:

• Define the absorption process for oral administration in the submenu Absorption:
  • zero-order or first-order absorption process with the associated paramameters (duration of absorption \(Tk0\) or absorption rate constant \(ka\))
  • lag time \(Tlag\)
  • transit compartment model with mean transit time \(Mtt\) and number of transit compartments \(Ntr\) (only for first-order absorption)

• Define the distribution process in the submenu Distribution:
  • 1, 2 or 3 compartments
  • volume of distribution \(V\)
  • transfer rates constants \(k_{12}\) and \(k_{21}\) between compartments 1 and 2
  • transfer rates constants \(k_{13}\) and \(k_{31}\) between compartments 1 and 3

• Define the elimination process in the submenu Elimination:
  • linear or Michaelis Menten elimination process
  • elimination rate constant \(k\), or
  • Michaelis Menten parameters \(V_m\) and \(K_m\).

Define the output in the menu Output:

• select the time range where the predicted concentration is computed,
• select the number of time points of the grid where the predicted concentration is computed,
• choose between linear and semi-log scale.