InVitro_Estimates_mapping

InVitro Estimates mapping panel

Once the in vitro dissolution and formulation data are mapped, the Estimates panel is used to specify parameter values for different formulations. (Options for initial value, lower bound, and upper bound are discussed in the “InVitro settings tab” section.)

All iterative estimation procedures require initial estimates of the parameters. Phoenix can compute initial estimates via curve stripping for single-dose PK, PD, PK/PD link, linear, or IVIVC models. For all other situations, initial estimates must be supplied or boundaries provided that will be used by Phoenix in creating initial estimates via grid search.

For IVIVC models only, some parameters can be assigned fixed values while others are estimated. The fixed command can be used for both modeling and simulating. Fixed parameters use a set value, so are no longer considered parameters. This reduces the number of parameters in the model. As an example, the fraction dissolved (Fdiss) can be fixed to 1.0 to prevent incomplete measurements from biasing other parameter estimates. Note that statistics such as VIF are not computed for fixed parameters.

None: Columns mapped to this context are not included in any analysis or output.

Sort: Map the formulation data to the Sort context to sort the parameter estimates by formulation.

Parameter: IVIVC model parameters.

Initial: Initial estimates for the parameter.

Fixed or Estimated: Whether the initial parameter is fixed or estimated.

Lower: (Available when User Supplied Bounds is selected in the InVitro tab) Lower boundary used for parameter estimates.

Upper: (Available when User Supplied Bounds is selected in the InVitro tab) Upper boundary used for parameter estimates.