Using dose (AMT) in Model

[Murali-Ramanathan]

Hi

I am relatively new to nlmixr.

I have a fairly standard depot compartment-central compartment model with a wrinkle

d/dt(depot) = -ka x DOSE x Function(t)
d/dt(centr) = ka x DOSE x Function(t) - k x centr

Is there a way to bring DOSE into model from the input data? I have a single bolus dose so there is no particular complexity.

Thanks
Murali

[mattfidler]

You typically add evid=1 and amt=dose in the dataset to have a bolus dose in the first compartment.

The ode would be:

d/dt(depot) = -ka * depot
d/dt(centr) = ka * depot - k * centr

Other sorts of doses are also allowed; See:

https://nlmixr2.github.io/rxode2/articles/rxode2-event-types.html

[mattfidler]

Also I develop nlmixr2 which is here:

https://nlmixr2.org

Since there hasn't been any activity on this repo for years, I am thinking of archiving it. If nlmixr comes back as another fork, they would want a separate repo probably anyway...

[Murali-Ramanathan]

Thanks Matt. I use nlmixr2 and will use that repository! I have no problem with the data file. I want to drag a data file variable into my model file.

[mattfidler]

Just refer to it by the name in the data file. It will be detected as a covariate

[Murali-Ramanathan]

Dear Matt I had a working version of nlmixr on my MacBook Pro. However, my nlmixr2 install stopped working when I tried to reinstall nlmixr2est thinking it would address a multi-threading issue. I have tried uninstalling and installing but keep running into issues. Here are the error messages. Error: package or namespace load failed for ‘nlmixr2’: .onLoad failed in loadNamespace() for 'nlmixr2est', details: call: NULL error: '.lbfgsb3cPtr' is not an exported object from 'namespace:lbfgsb3c' In addition: Warning message: package ‘nlmixr2’ was built under R version 4.3.3 Please help! Best regards, Murali

[mattfidler]

Use install.packages("lbfgsb3c")