Table 1.

Summary of population pharmacokinetic models

Model		Model 1	Model 2
Absorption model		First-order absorption with lag time
Elimination model	CLR	Linear	Michaelis-Menten-type nonlinear
	CLNR	Linear	Linear
Differential equation		$\begin{array}{c}\frac{{\mathit{dA}}_1}{\mathit{dt}}=-K_a{A}_1\end{array}$ $\begin{array}{c}\frac{{\mathit{dA}}_2}{\mathit{dt}}=K_a{A}_1-K_{\mathit{NR}}{A}_2-K_R{A}_2\end{array}$ $\begin{array}{c}\frac{{\mathit{dA}}_3}{\mathit{dt}}=K_R{A}_2\end{array}$	$\begin{array}{c}\frac{{\mathit{dA}}_1}{\mathit{dt}}=-K_a{A}_1\end{array}$ $\begin{array}{c}\frac{{\mathit{dA}}_2}{\mathit{dt}}=K_a{A}_1-K_{\mathit{NR}}{A}_2-\frac{V_{\mathit{max}}{A}_2/V}{K_m+A_2/V}\end{array}$ $\begin{array}{c}\frac{{\mathit{dA}}_3}{\mathit{dt}}=\frac{V_{\mathit{max}}{A}_2/V}{K_m+A_2/V}\end{array}$

CL_R renal clearance, CL_NR nonrenal clearance, t time, A adefovir amount in a compartment, adefovir amounts in the absorption, central, and urine compartments are represented by A₁, A₂, and A₃, respectively, K_a first-order absorption rate constant, V volume of distribution in the central compartment, K_NR linear nonrenal elimination rate constant, K_R linear renal elimination rate constant, K_m Michaelis-Menten constant for nonlinear renal elimination, V_max maximum rate of nonlinear renal elimination