est.thalf: Calculate Lambda_z and Elimination Half-life

In qpNCA: Noncompartmental Pharmacokinetic Analysis by qPharmetra

Description

Calculates lambda_z and thalf for each PK curve identified using by.

Usage

est.thalf(
  x,
  by = character(0),
  timevar = "time",
  depvar = "dv",
  includeCmax = "Y",
  exclvar = NA
)

Arguments

x	a dataset
by	column names in x indicating grouping variables
timevar	variable name containing the actual sampling time after dose
depvar	variable name containing the dependent variable (e.g., concentration)
includeCmax	include results of regression including Cmax in selection? (y/n); x$includeCmax overrides if provided
exclvar	a variable name containing information about points to be excluded (these should have exclvar = 1)

Details

The function starts with the last three sample points and performs log-linear regression on it. It then adds one sampling point at a time (including and ending at tmax) and performs the regression again. The results of the regression with the highest adjusted R-squared are returned.

Visual outliers can be excluded from the regression analysis.

Value

a dataset with estimates for each regression analysis in one observation. The following parameters are available.

• no.points number of data points used in the regression analysis

• intercept estimated intercept

• lambda_z -1*estimated slope

• r.squared square of the correlation coefficient

• adj.r.squared adjusted square of the correlation coefficient

• thalf elimination half-life

• start_th time of first sample included in the thalf estimation

• end_th time of last sample included in the thalf estimation

• includeCmax include results of regression including Cmax in selection? (y/n)

• points_excluded are time points excluded from the half-life estimation? (y/n)

Examples

example(correct.loq)
x %<>% mutate(includeCmax = 'Y')
th <- x %>% est.thalf(by='subject',exclvar=)
th %>%  head

qpNCA documentation built on Aug. 16, 2021, 5:08 p.m.