getnca: Perform non-compartmental pharmacokinetic analysis

In nlmixr2autoinit: Automatic Generation of Initial Estimates for Population Pharmacokinetic Modeling

Perform non-compartmental pharmacokinetic analysis

Description

Calculates key pharmacokinetic parameters using non-compartmental methods for both intravenous and oral administration data.

Usage

getnca(
  x,
  y,
  dose = 1,
  trapezoidal.rule = c("linear_up_log_down", "linear"),
  ss = 0,
  duration = NULL,
  nlastpoints = 3,
  slope.method = c("bestfitforce", "bestfit"),
  route = c("bolus", "oral", "infusion")
)

Arguments

x	Numeric vector of observation times.
y	Numeric vector of drug concentration measurements.
dose	Administered dose (default = 1).
trapezoidal.rule	Method for AUC calculation: "linear" - Linear trapezoidal method (default) "linear_up_log_down" - Linear-up/log-down method (linear for ascending concentrations, logarithmic for descending)
ss	Steady-state flag: 0 - Use extrapolated AUC_{0 \rightarrow \infty} for clearance (default) 1 - Use observed AUC_{0 \rightarrow \mathrm{last}} for clearance
duration	Infusion duration (required if route = "infusion").
nlastpoints	Number of terminal points for slope estimation (default = 3).
slope.method	Method for estimating terminal slope (\lambda_z): "bestfitforce" - Force estimation using decreasing number of terminal points if best-fit fails (default) "bestfit" - Use automated best-fit selection based on adjusted R-squared
route	Administration route: "bolus" - Intravenous bolus (default) "oral" - Oral administration "infusion" - Intravenous infusion

Value

A list containing:

• cl - Clearance (CL), calculated as Dose/AUC

• vz - volume of distribution (Vz), calculated as CL / lambdaz

• half_life - Terminal elimination half-life, computed as ln(2) / lambdaz

• auct - Area under the concentration–time curve from time 0 to last measurable concentration

• auc0_inf - AUC extrapolated to infinity

• C_last - Last non-zero measurable concentration

• lambdaz - Terminal elimination rate constant

• aumc_0_t - Area under the first moment curve from time 0 to last measurable concentration

• aumc_0_inf - AUMC extrapolated to infinity

• used_points - Number of time–concentration points used to estimate lambdaz

• adj.r.squared - Adjusted R-squared of the terminal phase regression

• messages - Warning or diagnostic messages returned during the calculation

Examples

# IV bolus example
dat <- data.frame(TIME = c(0.5, 1, 2, 4, 6, 8),
                  DV = c(12, 8, 5, 3, 2, 1))
getnca(x = dat$TIME, y = dat$DV, dose = 1)

# IV infusion example
dat <- data.frame(TIME = c(0.5, 1, 2, 4, 6, 8),
                  DV = c(2, 8, 5, 3, 2, 1))
getnca(x = dat$TIME, y = dat$DV, dose = 1, route = "infusion", duration = 1)

# Oral administration example
dat <- data.frame(TIME = c(0, 1, 2, 4, 6, 8),
                  DV = c(0, 9, 12, 8, 6, 2))
getnca(x = dat$TIME, y = dat$DV, route = "oral")

nlmixr2autoinit documentation built on Nov. 14, 2025, 1:07 a.m.