Graphical calculation of pharmacokinetic parameters for oral administration

Estimates key pharmacokinetic parameters from oral concentration–time data using graphical methods, including absorption rate constant (ka), elimination rate constant (kel), terminal slope, extrapolated concentration (C0exp), apparent volume of distribution (Vd/F), and clearance (Cl/F).

Usage

graphcal_oral(dat, dose = 1, ...)

Arguments

dat

A data frame containing TIME (time after dosing) and DV (observed concentration).

dose

Administered dose amount. Defaults to 1.

...

Additional arguments passed to find_best_lambdaz().

Value

A list containing graphical estimates of ka, kel, lambda_z, C0exp, Vd/F, and Cl/F.

Details

The terminal slope (lambdaz) is estimated using force_find_lambdaz(). The apparent volume of distribution and clearance are computed using the following relationships: $$Vd/F = \frac{Dose \times ka}{C_0 \times (ka - kel)}$$ $$Cl/F = kel \times Vd/F$$ where ka is estimated from the absorption phase.

See also

find_best_lambdaz

Author

Zhonghui Huang

Examples

dat <- data.frame(TIME = c(0.5, 1, 2, 4, 6, 8, 10),
                  DV = c(1, 2, 5, 3, 2, 1.5, 1))
graphcal_oral(dat, dose = 100, route = "oral")
#> $ka
#> [1] 0.6801746
#> 
#> $kel
#> [1] 0.1791759
#> 
#> $slope
#> [1] -0.1791759
#> 
#> $C0exp
#> [1] 6.071088
#> 
#> $cl
#> [1] 4.006794
#> 
#> $vd
#> [1] 22.36235
#> 
#> $method
#> [1] "find_best_lambdaz"
#> 
#> $slopefit
#> 
#> Call:
#> lm(formula = log(conc[subset]) ~ time[subset])
#> 
#> Coefficients:
#>  (Intercept)  time[subset]  
#>       1.8035       -0.1792  
#> 
#> 
#> $time.spent
#> [1] 0.003
#>