Estimate absorption rate constant in a one-compartment oral model

This estimates the absorption rate constant in a single-dose oral model using first-order pharmacokinetics.

Usage

ka_calculation_sd(cl, ke, t, Ct, Fbio = 1, Dose)

Arguments

cl: Numeric. Clearance of the drug.
ke: Numeric. Elimination rate constant.
t: Numeric. Time after administration.
Ct: Numeric. Observed plasma concentration at time t.
Fbio: Numeric. Absolute bioavailability fraction. Default is 1.
Dose: Numeric. Administered oral dose.

Value

A list containing:

ka: Estimated absorption rate constant.
full_solution: The full result object returned by the root-finding process.
message: A character string indicating the status of the estimation or any warnings.

Details

The model assumes a one-compartment structure with first-order absorption and first-order elimination.

The concentration-time relationship is: $$Ct = \frac{Fbio \cdot Dose \cdot ka}{Vd \cdot (ka - ke)} \left( e^{-ke \cdot t} - e^{-ka \cdot t} \right)$$ where the volume of distribution is defined as: $$Vd = \frac{cl}{ke}$$

ka is estimated using uniroot(), which solves for the root of the residual function (predicted Ct - observed Ct) within a bounded interval (ka > ke and ka <= 1000)

Author

Zhonghui Huang

Examples

# Example from Oral_1CPT dataset (ID = 1, 1st dose, t = 0.5 h)
ka_calculation_sd(cl = 3.62, ke = 0.0556, t = 0.5, Ct = 310.6, Dose = 60000)
#> $ka
#> [1] 0.837342
#> 
#> $full_solution
#> $full_solution$root
#> [1] 0.837342
#> 
#> $full_solution$f.root
#> [1] 7.349658e-05
#> 
#> $full_solution$iter
#> [1] 11
#> 
#> $full_solution$init.it
#> [1] NA
#> 
#> $full_solution$estim.prec
#> [1] 6.103516e-05
#> 
#> 
#> $message
#> [1] "complete"
#>