New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Advice on Fitting My Rifampin Model Better? #222

yishuanwu opened this Issue Sep 10, 2018 · 2 comments


None yet
3 participants

yishuanwu commented Sep 10, 2018
Hi, I am working on building a Rifampin IV model. I am still working on fitting the adult model and have not started on the induction/inhibition processes. Ultimately, I would like to use it for neonatal DDI predictions.

I know there is a rifampin model in the template but I hope to improve on that model, and also I did not understand how it derived some of the parameters. I found a range of values in the literature for some parameters (e.g. LogP from 2.7 to 3.13, and fu from 0.125 to 0.175) and I was missing rifampin transport kinetic data. I arbitrarily set the Km of the P-gp to 1 just so I can use parameter identification to get a Vmax. I kept trying to play with each of the parameters but my model is still overestimating Cmax.

Please see the attached. RIF0 is the PK-Sim template, RIF3 is the model that I am working on. In the below images, my model is showed using dashed lines.
Adult Data

Neonate Data


This comment has been minimized.


sfrechen commented Sep 12, 2018

You may get some additional insights here:
and in our respective publication:

If that does not answer all your questions we are happy to give further support.


This comment has been minimized.

yishuanwu commented Sep 15, 2018

Hi Dr. Frechen,
Thank you for your reply. My main concern is that the model does not seem to be describing neonatal data well, which was not part of your paper. But your paper was very insightful for me.

@Yuri05 Yuri05 added the help wanted label Sep 20, 2018

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment