get_hf: Estimate half-life from pooled pharmacokinetic data

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

Estimate half-life from pooled pharmacokinetic data

Description

Estimates the terminal half-life of a drug using pooled pharmacokinetic data. The method supports analysis based on first-dose, repeated-dose, or combined dosing profiles.

Usage

get_hf(dat, dose_type = "first_dose", pooled = NULL, verbose = TRUE, ...)

Arguments

dat	A data frame containing raw time–concentration data in the standard nlmixr2 format.
dose_type	Specifies the dosing context of the pharmacokinetic observations. Classified as: first_dose: observations occur only after the initial administration repeated_doses: observations occur only after multiple administrations or at steady state combined_doses: observations include both first-dose and repeated-dose intervals
pooled	Optional pooled data object generated by get_pooled_data. If not provided, pooled data are automatically created using the input dataset.
verbose	Logical; if TRUE (default), progress and completion messages are printed to the console. Set to FALSE to suppress all informational messages, for example when running automated scripts or tests.
...	Additional arguments passed to bin.time for pooling operations or to find_best_lambdaz for elimination slope estimation.

Details

The function estimates terminal half-life using the following procedure:

• Generate or use existing pooled pharmacokinetic data

• Identify the terminal phase using elimination slope estimation

• Calculate the terminal elimination rate constant (lambda_z)

• Derive half-life using:

t_{1/2} = \frac{\log(2)}{\lambda_z}

Value

A list containing individual and median half-life estimates for first-dose, repeated-dose, and combined dosing profiles.

Author(s)

Zhonghui Huang

See Also

get_pooled_data, bin.time, find_best_lambdaz

Examples

dat <- Bolus_1CPT
dat <- processData(dat)$dat
get_hf(dat, dose_type = "combined_doses")

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