Calculate AUXC (AUC or AUMC) for IV dosing with C0 back-extrapolation

Calculates AUC or AUMC for intravenous dosing, with optional back-extrapolation to C0.

Usage

pk.calc.auxciv(
  conc,
  time,
  c0,
  auxc,
  fun_auxc_last,
  fun_auxc,
  auc.type = NULL,
  lambda.z = NA,
  clast = NA,
  ...,
  options = list(),
  check = TRUE
)

pk.calc.auciv(
  conc,
  time,
  c0,
  auc,
  auc.type = NULL,
  lambda.z = NA,
  clast = NA,
  ...,
  options = list(),
  check = TRUE
)

pk.calc.auciv_pbext(
  conc,
  time,
  auc,
  auciv,
  ...,
  options = list(),
  check = TRUE
)

pk.calc.aumciv(
  conc,
  time,
  c0,
  aumc,
  auc.type = NULL,
  lambda.z = NA,
  clast = NA,
  ...,
  options = list(),
  check = TRUE
)

Arguments

conc: Measured concentrations
time: Time of the measurement of the concentrations
c0: The concentration at time 0, typically calculated using pk.calc.c0()
auxc: The AUXC calculated using conc and time without c0 (it may be calculated using any method)
fun_auxc_last: Function to calculate the AUXC for the last interval (e.g., pk.calc.auc.last or pk.calc.aumc.last)
fun_auxc: Function to calculate the AUXC over the full interval when auxc could not be calculated (e.g., pk.calc.auc or pk.calc.aumc)
auc.type: The type of AUXC for fun_auxc to calculate. NULL (the default) means that the AUXC will not be calculated from c0 and the measured data, so NA is returned when auxc is NA.
lambda.z: The elimination rate (in units of inverse time) for extrapolation
clast: The last concentration above the limit of quantification, used by fun_auxc when auc.type is "AUCinf" (clast.obs gives AUCinf,obs and clast.pred gives AUCinf,pred)
...: For functions other than pk.calc.auxc, these values are passed to pk.calc.auxc
options: List of changes to the default PKNCA options (see PKNCA.options())
check: Run assert_conc_time()?
auc: The AUC calculated without C0 back-extrapolation
auciv: The AUC calculated using c0
aumc: The AUMC calculated using conc and time without c0

Value

The AUXC calculated using c0

pk.calc.auciv_pctbackextrap: The AUC percent back-extrapolated

Details

The AUXC for intravenous (IV) dosing extrapolates the AUXC back from the first measurement to time 0 using c0 and the AUXC calculated by another method (e.g., auclast or aumclast).

How the calculation proceeds depends on what is measured at time = 0:

A concentration is measured at time = 0: The AUXC between time = 0 and the next time point is calculated with the measured concentration (auxc_first) and with c0 (auxc_second). The final AUXC is auxc + auxc_second - auxc_first.
No concentration at time = 0 and auxc was calculated: auxc comes from a method that extrapolates back to time = 0 with conc.origin (zero; the aucint family), so that segment is replaced by the one using c0 in the same way.
No concentration at time = 0 and auxc is NA: auxc is NA because an AUXC may not start before the first measurement. c0 supplies that measurement, so the AUXC is calculated here from c0 and the measured data using fun_auxc and auc.type.

The calculation for back-extrapolation is 100*(1 - auc/auciv). It requires a measured concentration at time 0; without one, auc does not describe the observed part of auciv (it either cannot be calculated or, for the aucint family, already extrapolates back to time 0 with conc.origin), so NA is returned.

Functions

pk.calc.auciv(): Calculate AUC for intravenous dosing with C0 back-extrapolation
pk.calc.auciv_pbext(): Calculate the percent back-extrapolated AUC for IV administration
pk.calc.aumciv(): Calculate AUMC for intravenous dosing with C0 back-extrapolation