ka_calculation_sd: Estimate absorption rate constant in a one-compartment oral model
Description
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)
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.
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.
Author
Zhonghui Huang
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)