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Concentration in Stomach #489

Closed JoseDavidGomez closed 4 years ago

JoseDavidGomez commented 4 years ago

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 commented 4 years ago

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 commented 4 years ago

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 commented 4 years ago

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, Liquidthe volume of the liquid in the lumen segment, and MWis the molecular weight of the compound.

Yuri05 commented 4 years ago

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))

jzq90 commented 4 years ago

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 commented 4 years ago

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

Yuri05 commented 4 years ago

@JoseDavidGomez Closing. Please reopen if there are still any unanswered questions.