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Reference/documentation for SITT and LITT #580

Closed moPellowe closed 3 years ago

moPellowe commented 4 years ago

I'm looking for a reference or documentation regarding the "small intestinal transit time factor" and the "large intestinal transit time factor" parameters. I don't understand the equations for both factors as well as how the linear equation was parameterized.

JanSchlender commented 4 years ago

Hi moPellowe, Have you had a look at the two publications on the establishement of the current GI-tract in PK-Sim? https://pubmed.ncbi.nlm.nih.gov/21993815/ https://pubmed.ncbi.nlm.nih.gov/22125236/ Best, Jan

PavelBal commented 4 years ago

I did, and I didn't get far - so @moPellowe if you do understand the equations after reading these two publications, I would be happy to discuss it with you.

Yuri05 commented 4 years ago

Intestinal transit rates were fitted to match experimental intestinal transit data (s. figure 1 of the article https://pubmed.ncbi.nlm.nih.gov/21993815/)

Using those factors is more for historical reasons; small/large intestinal transit time can be used directly s. Open-Systems-Pharmacology/PK-Sim/Issues/1541

Yuri05 commented 4 years ago

@katrincoboeken @AndreDlm FYI

moPellowe commented 4 years ago

Thank you for the references and the explanations. I will give them a read and let you know if I have any additional questions.

StephanSchaller commented 4 years ago

@moPellowe , have you figured out how the SITT factor is derived? (how P1 and P2 were fitted) and the transit times for each gut segment?

moPellowe commented 4 years ago

@StephanSchaller and @PavelBal , actually no, I still don't understand how the SITT factor is derived (i.e. P1 and P2). I skimmed the two articles that were given above by @JanSchlender , and I can see how the intestinal segment transit rates (before scaling?) could be derived from Figure 1A of the first article https://pubmed.ncbi.nlm.nih.gov/21993815/ as @Yuri05 mentioned, but I still don't understand where the SITT/LITT factor equations come from. Does anyone have any insight into those equations?