calc_css: Find the steady state concentration and the day it is reached.

Description

This function finds the day a chemical comes within the specified range of the analytical steady state venous blood or plasma concentration(from calc_analytic_css) for the multiple compartment, three compartment, and one compartment models, the fraction of the true steady state value reached on that day, the maximum concentration, and the average concentration at the end of the simulation.

Usage

calc_css(
  chem.name = NULL,
  chem.cas = NULL,
  dtxsid = NULL,
  parameters = NULL,
  species = "Human",
  f = 0.01,
  daily.dose = 1,
  doses.per.day = 3,
  dose.units = "mg/kg",
  route = "oral",
  days = 21,
  output.units = "uM",
  suppress.messages = FALSE,
  tissue = NULL,
  model = "pbtk",
  f.change = 1e-05,
  dosing = NULL,
  parameterize.args.list = list(),
  ...
)

Value

frac: Ratio of the mean concentration on the day steady state is reached (baed on doses.per.day) to the analytical Css (based on infusion dosing).
max: The maximum concentration of the simulation.
avg: The average concentration on the final day of the simulation.
the.day: The day the average concentration comes within 100 * p percent of the true steady state concentration.

Arguments

chem.name: Either the chemical name, CAS number, or parameters must be specified.
chem.cas: Either the chemical name, CAS number, or parameters must be specified.
dtxsid: EPA's DSSTox Structure ID (https://comptox.epa.gov/dashboard) the chemical must be identified by either CAS, name, or DTXSIDs
parameters: Chemical parameters from parameterize_pbtk function, overrides chem.name and chem.cas.
species: Species desired (either "Rat", "Rabbit", "Dog", "Mouse", or default "Human").
f: Fractional distance from the final steady state concentration that the average concentration must come within to be considered at steady state.
daily.dose: Total daily dose, mg/kg BW.
doses.per.day: Number of oral doses per day.
dose.units: The units associated with the dose received.
route: Route of exposure (either "oral", "iv", or "inhalation" default "oral").
days: Initial number of days to run simulation that is multiplied on each iteration.
output.units: Units for returned concentrations, defaults to uM (specify units = "uM") but can also be mg/L.
suppress.messages: Whether or not to suppress messages.
tissue: Desired tissue concentration (default value is NULL, will depend on model -- see steady.state.compartment in model.info file for further details.)
model: Model used in calculation, 'pbtk' for the multiple compartment model,'3compartment' for the three compartment model, and '1compartment' for the one compartment model.
f.change: Fractional change of daily steady state concentration reached to stop calculating.
dosing: The dosing object for more complicated scenarios. Defaults to repeated daily.dose spread out over doses.per.day
parameterize.args.list: Named list of any additional arguments passed to model parameterization function (other than the already-named arguments). Default `list()` to pass no additional arguments.
...: Additional arguments passed to solve_model (defaults model is "pbtk").

Author

Robert Pearce, John Wambaugh

Examples

Run this code


calc_css(chem.name='Bisphenol-A',doses.per.day=5,f=.001,output.units='mg/L')

# \donttest{
parms <- parameterize_3comp(chem.name='Bisphenol-A')
parms$Funbound.plasma <- .07
calc_css(chem.name='Bisphenol-A',parameters=parms,model='3compartment')

out <- solve_pbtk(chem.name = "Bisphenol A",
  days = 50,
  daily.dose=1,
  doses.per.day = 3)
plot.data <- as.data.frame(out)

css <- calc_analytic_css(chem.name = "Bisphenol A")
library("ggplot2")
c.vs.t <- ggplot(plot.data,aes(time, Cplasma)) + geom_line() +
geom_hline(yintercept = css) + ylab("Plasma Concentration (uM)") +
xlab("Day") + theme(axis.text = element_text(size = 16), axis.title =
element_text(size = 16), plot.title = element_text(size = 17)) +
ggtitle("Bisphenol A")

print(c.vs.t)
# }