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I have a species which is absorbed in a zero-order manner. I want to model the reaction rate as "UptakeRate*ActiveState". So I can give value of 1 or 0 to ActivateState to control the active state of this process. The species itself is under control multiple processes, so I want to use Event to automatically change the active state of absorption.
However, when I use these two events:
Event 1，trigger: species > 0, Function: ActiveState =1; Event 2, trigger: species <=0, Function: ActiveState=0
The simulation seems to be stuck without stop.
Is there any way to solve this ? Thanks
Wei Wang
Wei Wang
Last activity on 10 Jul 2020

Why assume Cup is equal to Cub

Hi, all

Recently I read the book "Physiologically Based Pharmacokinetic (PBPK) Modeling and Simulations: Principles, Methods, and Applications in the Pharmaceutical Industry" and find this state,"Since the unbound concentrations in plasma and blood are expected to be the same, fub , fup , and R are related as follows: R=Cb/Cp=(Cub·fup)/(Cup·fub) and R=fup/fub". I don't know whether it is reasonable to generally assume unbound concentrations in plasma and blood to be the same since components in whole blood and plasma are not the same. Is it common to see this equality in real situation?

Thanks for comment.

Hi, all friends,

I want to record the fraction of drug absorbed in each intestinal segment, so I define a set of parameters with rate rule like: AbFraction_Colon= ((PeffColon*2/organismRadiusColon+paracellularAbsorption*organismFluxMucosaSerosa/Colon)*Colon.DrugDissolved)*Colon/InitialDose The attached figure shows the simulation result that overall PK profile (purple) seems OK, but I don't know why the absorption fraction line (red) starts from value of 1. Does anyone know the cause?

By the way, I am using model modified from "generic PBPK model"

Thanks for comment.

Wei Wang
Wei Wang
Last activity on 5 Apr 2020

Be confused by a NCA result

Hi, all friends

I am dealing with a confusing NCA result. As this result shows, AUC_infinity=0.8537 (μg*h/mL), DM=1 (mg). CL should be equal to DM/AUC_infinity but why is the calculated result 2.4491? There is no dimension along with value so I do not know if I ignore anything.

Does any one can handle with this situation? Thanks very much. I also post my used data (i.v.).

Hi, all friends

If I define a parameter, like solubility with dimension of milligram/milliliter and I want to refer it in an reaction equation in dimension of millimole/liter, suppose I have define its molecularweight, could I input this parameter directly in equation with specified dimension?

Hi, all friends

I am working on building a oral model with "Generic SimBiology PBPK model" and meet some problems about intestinal transit rate. Take duodenum as example, the transit rate is defined as " (kTransportSmallIntestine*organismLengthDuodenum/organismLengthSmallInstestine)*Duodenum.DrugDissolved". I think assuming duodenum transit time is equal to SmallIntestineTransittime*organismLengthDuodenum/organismLengthSmallInstestine, the transit rate constant is the inverse of that,which result in kTransportSmallIntestine*organismLengthSmallInstestine/organismLengthDuodenum, contradicting with the equation in model. Am I wrong?

Besides that, the kTransportSmallIntestine_is defined as _0.693/organismMeanResidenceSmallIntestine in model. Isn't the mean residence time determining the time at which about 63.2% of initial amount having passed through the compartment and inverse of mean residence time determining the transit rate? Why does organismMeanResidenceSmallIntestine correlate with 0.693 which is often seen in half-life associated expression?

Thanks for any comment.

Hi, fellows,

I am a new user of MATLAB and SimBiology. When I open the "Generic SimBiology Physiologically-based Pharmacokinetic (PBPK) model" downloaded from "https://ww2.mathworks.cn/matlabcentral/fileexchange/37752-generic-simbiology-physiologically-based-pharmacokinetic-pbpk-model", I get a note of "Copyright 2012-2018 The MathWorks, Inc. ...". Does that mean I can not access to the model built-in or make any modification?

Thanks for any comment!