how to model blood volume change during and after hemodialysis?

Dear nmusers, I would like to model PK profiles of a compounds which mostly distributes in blood volume. The subjects which were investigated underwent hemodialysis for approx. the first three hours after infusion start, and the compound was given over a time period of ~5-10 min. It is well known that during hemodialysis, blood volume changes. Therefore, I would like to add a dynamic component to the central volume parameter, allowing it to decrease during hemodialysis and then to reincrease after dialysis has ended. I have all information about start and end time of both dosing and dialysis. Individual times between subjects differed. Unfortunately, I have not been creative enough to come up with a NONMEM code that can do this. Could any of you help out? Also, I probably do not have late enough time points to estimate when exactly blood volume would be restored. Does anyone know how much time the body needs after dialysis has ended until it is back to the original blood volume? Thanks for your help and best Nele ______________________________________________________________ Dr. Nele Käßner Principal Scientist Modeling and Simulation Global Pharmacometrics Experimental Medicine Takeda Pharmaceuticals International GmbH Thurgauerstrasse 130 8152 Glattpark-Opfikon (Zürich) Switzerland Visitor address: Alpenstrasse 3 8152 Glattpark-Opfikon (Zürich) Switzerland Phone: (+41) 44 / 55 51 404 Mobile: (+41) 79 / 654 33 99 mailto: [email protected]<mailto:[email protected]> http://www.takeda.com -------------------------------------------------------------------- The content of this email and of any files transmitted may contain confidential, proprietary or legally privileged information and is intended solely for the use of the person/s or entity/ies to whom it is addressed. If you have received this email in error you have no permission whatsoever to use, copy, disclose or forward all or any of its contents. Please immediately notify the sender and thereafter delete this email and any attachments.