add_allometry {pharmr}

add_allometry

Description

Add allometric scaling of parameters

Add an allometric function to each listed parameter. The function will be P=P*(X/Z)**T where P is the parameter, X the allometric_variable, Z the reference_value and T is a theta. Default is to automatically use clearance and volume parameters.

If there already exists a covariate effect (or allometric scaling) on a parameter with the specified allometric variable, nothing will be added.

If no allometric variable is specified, it will be extracted from the dataset based on the descriptor "body weight".

Usage

add_allometry(
  model,
  allometric_variable = NULL,
  reference_value = 70,
  parameters = NULL,
  initials = NULL,
  lower_bounds = NULL,
  upper_bounds = NULL,
  fixed = TRUE
)

Arguments

model

(Model) Pharmpy model

allometric_variable

(str or Expr (optional)) Value to use for allometry (X above)

reference_value

(numeric or str or Expr) Reference value (Z above)

parameters

(array(numeric or str or Expr) (optional)) Parameters to use or NULL (default) for all available CL, Q and V parameters

initials

(array(numeric) (optional)) Initial estimates for the exponents. Default is to use 0.75 for CL and Qs and 1 for Vs

lower_bounds

(array(numeric) (optional)) Lower bounds for the exponents. Default is 0 for all parameters

upper_bounds

(array(numeric) (optional)) Upper bounds for the exponents. Default is 2 for all parameters

fixed

(logical) Whether the exponents should be fixed

Value

(Model) Pharmpy model object

Examples

## Not run: 
model <- load_example_model("pheno")
model <- remove_covariate_effect(model, 'CL', 'WGT')
model <- remove_covariate_effect(model, 'V', 'WGT')
model <- add_allometry(model, allometric_variable='WGT')
model$statements$before_odes

## End(Not run)