tci (version 0.1.2)

pk_basic_solution_3cpt_metab: Solution to three-compartment IV model

Description

3 compartment IV infusion with first-order absorption between compartments and with an additional effect-site compartment. The analytical solutions implemented in this function are provided in "ADVAN-style analytical solutions for common pharmacokinetic models" by Abuhelwa et al. 2015.

Usage

pk_basic_solution_3cpt_metab(
  kR,
  k10,
  k12,
  k21,
  k13,
  k31,
  v1,
  v2,
  v3,
  ke0,
  c0 = c(0, 0, 0, 0)
)

Value

Numeric matrix of concentrations for a constant infusion rate

Arguments

kR

Infusion rate (e.g. ml/min).

k10

Rate of excretion from central compartment.

k12

Rate of transfer from compartment 1 to compartment 2.

k21

Rate of transfer from compartment 2 to compartment 1.

k13

Rate of transfer from compartment 1 to compartment 3.

k31

Rate of transfer from compartment 3 to compartment 1.

v1

Volume of compartment 1.

v2

Volume of compartment 2.

v3

Volume of compartment 3.

ke0

Rate of transfer from effect-site compartment to compartment 1.

c0

Initial concentrations. Defaults to 0 in each compartment.

Details

This function takes in arguments for each of the absorption and elimination rate constants of a three-compartment model as well as initial concentrations, c0. ke0 gives the rate of elimination from the effect-site compartment into the central compartment (i.e. k41). The rate of absorption into the effect-site compartment is set at 1/10,000 the value of ke0. The function returns a set of functions that calculate the concentration in each of the four compartments as a function of time.

Examples

data(eleveld_pk)
data(eleveld_pd)
pk_vars <- c("V1","V2","V3","CL","Q2","Q3")
pd_vars <- c("E50","KE0","EMAX","GAM","GAM1","RESD")
pk_pars <- subset(eleveld_pk, ID == 403, select = pk_vars)
pd_pars <- subset(eleveld_pd, ID == 403, select = pd_vars)

sol <- pk_basic_solution_3cpt_metab(kR = 1,
                                    k10 = pk_pars$CL / pk_pars$V1,
                                    k12 = pk_pars$Q2 / pk_pars$V1,
                                    k21 = pk_pars$Q2 / pk_pars$V2,
                                    k13 = pk_pars$Q3 / pk_pars$V1,
                                    k31 = pk_pars$Q3 / pk_pars$V3,
                                    v1 = pk_pars$V1,
                                    v2 = pk_pars$V2,
                                    v3 = pk_pars$V3,
                                    ke0 = pd_pars$KE0,
                                    c0 = c(0,0,0,0))
# concentration in central and effect site compartments
tms <- seq(0,1,0.1)
cbind(sol$c_1(tms), sol$c_4(tms))