rxode2 and setting F1 to unfixed values

[pharmax-lisa]

Hi I'm trying to use rxode2 to create a model that is a modified release model with two depots. We were able to use NONMEM to estimate F1(bioavailability of modified release) and F3 (bioavailability of immediate release). The model works great but it's not picking up F1 or F3.

ode <- "
C2=centr/V2;

C4=peri1/V4;

d/dt(depot) = -K12depotF1; #F1 and K12 and ALAG are MR
alag(depot) = lag1;

d/dt(centr)= F1depotK12+F3depot2K32-CLC2-Q(C2-C4);
d/dt(depot2) = -K32depot2F3; #F3 is IR

d/dt(peri1) = Q*(C2-C4);
"
And this dosing event:
ev$add.dosing(dose = dose, nbr.doses = ncyc, dosing.interval = reg,
start.time=0,cmt="depot")
ev$add.dosing(dose = dose, nbr.doses = ncyc, dosing.interval = reg,
start.time=0,cmt="depot2")

Please help! Thanks in advance. Lisa

[mattfidler]

Hi @pharmax-lisa

In general you should use:

f(depot) = fdepot1

If you are simply trying to import into rxode2, there is a new package that can help:

https://github.com/nlmixr2/nonmem2rx

[pharmax-lisa]

Thanks! I'll try this out

[mattfidler]

Hopefully it works for you!