# Combination of oral and iv administrations

[LONGITUDINAL]
input = {F, ka, V, k}

PK:
depot(type=2, target=Ac)

EQUATION:
Cc = Ac/V
adm1 <- list(time=c(6, 36), amount=40, type=1)
adm2 <- list(time=c(12,42), amount=c(20,30), rate=c(5, 10), type=2)
p    <- list(name=c("F","ka","V","k"), value=c(0.7,1,10,0.1))
Cc   <- list(name="Cc",time=seq(0, 60, by=0.1))
res  <- simulx(model="pk2a_model.txt",parameter=p,output=Cc,treatment=trt)

print(ggplot(data=res\$Cc, aes(x=time, y=Cc)) + geom_line())

#### Combination of repeated oral and intravenous administrations

Let $$A_d$$ and $$A_c$$ be, respectively, the amounts in the depot compartment (gut) and the central compartment (bloodtsream). Kinetics of $$A_d$$ and $$A_c$$ are described by the following system of ODEs \begin{aligned} \dot{A_d}(t) & = - ka \, A_d(t) \\ \dot{A_c}(t) & = ka \, A_d(t) - k \, A_c(t) \end{aligned}

The concentration $$C_c$$ in the central compartment is defined by $$\ \ C_c(t) = A_c(t)/V$$

• Define the dosage regimen for the intravenous (iv) administration in the tab iv: time of first dose, number of doses, interdose interval, infusion time, amount.

• Define the dosage regimen for the oral administration in the tab oral: time of first dose, number of doses, interdose interval, amount.

• select the PK parameters in the tab parameters:
• $$F$$, the bioavalabililty (a fraction between 0 and 1) ,
• $$ka$$, the absorption rate constant,
• $$V$$, the volume of the central compartment.
• $$k$$, the elimination rate constant,

• define the outputs in the tab outputs :
• select the output to display: the amount $$A_d$$ or $$A_c$$, or the concentration $$C_c$$,
• select the time range where the prediction is computed,
• select the number of time points of the grid where the prediction is computed.

• set some settings in the tab settings: line width, linear or semi-log scale.