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Concentration in Stomach #489

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JoseDavidGomez opened this issue Mar 23, 2020 · 6 comments
Open

Concentration in Stomach #489

JoseDavidGomez opened this issue Mar 23, 2020 · 6 comments
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@JoseDavidGomez
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@JoseDavidGomez JoseDavidGomez commented Mar 23, 2020

Dear Comunity,

I cannot find in the manual how are the concentration in stomach calculated after oral administration.

Does it consider the whole lumen volumen (1.57l) or is there a way to know the fluid volume that is considered?

Thank you!

JD

@PavelBal

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@PavelBal PavelBal commented Mar 23, 2020

All lumen compartments have the parameter Liquid. Most of the processes taking place in lumen (such as absorption etc.) calculate the dissolved concentration of the drug as Amoung/Liquid.

@JoseDavidGomez

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@JoseDavidGomez JoseDavidGomez commented Mar 25, 2020

By rough calculations from the simulation stomach_concentration/dose in a solution, i get a liquid volume of around 1.9L. Does it make any sense? I thought fluid volume in the stomach was less than 500 mL.

@PavelBal

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@PavelBal PavelBal commented Mar 25, 2020

The liquid volume in stomach is by default around 400 ml, additional to that the volume you administer with the application (around 250 ml).

In PK-Sim, there is no output for the concentration of drug in lumen liquid (I think it should be there), so there is no direct way to plot it in PK-Sim. In MoBi, you will find this parameter under Organism|Lumen|LumenSegment|DrugName|Effective concentration in lumen, the formula for which is

EnableSupersaturarion ? M/Liquid : min(Solubility/MW ; M/Liquid)

M is the amount of the molecule, Liquid the volume of the liquid in the lumen segment, and MW is the molecular weight of the compound.

@Yuri05

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@Yuri05 Yuri05 commented Mar 25, 2020

In PK-Sim, there is no output for the concentration of drug in lumen liquid (I think it should be there), so there is no direct way to plot it in PK-Sim

I must correct: luminal concentration plotted in PK-Sim is exactly the effective concentration given by the formula above
(EnableSupersaturarion ? M/Liquid : min(Solubility/MW ; M/Liquid))

@Yuri05 Yuri05 added the question label Mar 25, 2020
@jzq90

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@jzq90 jzq90 commented Mar 26, 2020

The liquid volume in the stomach is by default around 400 ml, additional to that the volume you administer with the application (around 250 ml).

Why the default liquid in my model is only 50 mL? Isn't this is too small?
图片

@Yuri05

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@Yuri05 Yuri05 commented Mar 26, 2020

Why the default liquid in my model is only 50 mL? Isn't this is too small?

This is not too small. Default liquid volume in adults in fasted state is around 45 ml.
S. e.g. https://www.ncbi.nlm.nih.gov/pubmed/18602774

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