calc_half_life: Calculates the half-life for a one compartment model.

In httk: High-Throughput Toxicokinetics

Calculates the half-life for a one compartment model.

Description

This function calculates the half life from the three compartment steady state model where elimination is entirely due to metabolism by the liver and glomerular filtration in the kidneys.

Usage

calc_half_life(
  chem.cas = NULL,
  chem.name = NULL,
  dtxsid = NULL,
  parameters = NULL,
  species = "Human",
  model = "3compartmentss",
  suppress.messages = TRUE,
  ...
)

Arguments

chem.cas	Either the cas number or the chemical name must be specified.
chem.name	Either the chemical name or the cas number 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_steadystate or 1compartment function, overrides chem.name and chem.cas.
species	Species desired (either "Rat", "Rabbit", "Dog", "Mouse", or default "Human").
model	The model used to calculate elimination rate (defaults to "3compartmentss")
suppress.messages	Whether or not the output message is suppressed.
...	Additional parameters passed to parameterize function if parameters is NULL.

Details

Half life is calculated by dividing the natural-log of 2 by the elimination rate from the one compartment model.

Value

Half life

Units of h.

Author(s)

Sarah E. Davidson

See Also

calc_elimination_rate

Examples

calc_half_life(chem.name="Bisphenol A")

calc_half_life(chem.name="Bisphenol A",species="Rat")

calc_half_life(chem.cas="80-05-7")

# Volatiles are outside the domain of default model:
try(calc_half_life(
     chem.name="toluene"))

# We can turn off physchem checking:
calc_half_life(
     chem.name="toluene",
     physchem.exclude=FALSE)

# Or use an appropriate model for volatiles:
calc_half_life(
     chem.name="toluene",
     model="sumclearances")

# PFAS are outside the domain:
try(calc_half_life(
     dtxsid="DTXSID8031865",
     model="sumclearances"))

# Can turn off chemical class checking:
calc_half_life(
  dtxsid="DTXSID8031865",
  model="sumclearances",
  class.exclude=FALSE,
  suppress.messages=TRUE)

# For a metabolized compound, non-restrictive clearance should be faster:
h1 <- calc_half_life(
  chem.name="toluene",
  model="sumclearances",
  suppress.messages=TRUE)
h2 <- calc_half_life(
  chem.name="toluene",
  model="sumclearances",
  restrictive.clearance=FALSE,
  suppress.messages=TRUE)
# Check that h2 < h1:
if (!(h2 < h1)) stop("h2 not less than h1")

# Change species: 
calc_half_life(
  dtxsid="DTXSID8031865",
  species="rat",
  model="sumclearances",
  default.to.human=TRUE,
  class.exclude=FALSE,
  physchem.exclude=FALSE,
  suppress.messages=TRUE)

httk documentation built on June 8, 2025, 12:19 p.m.