nlmixr2autoinit (version 1.0.0)

getnca: 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")
)

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

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

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")