Bioequivalence and Bioavailability Forum

Dear Łukasz!

❝ Does anyone know if there are any specific guidelines about calculation of elimination constant rate?

No specific text I know of – just ambigous wording like ‘a reliable estimate, ’.

❝ Specifically, is there any limit of correlation coefficient below which calculation of Kel should not be perfomed?

The correlation coefficient is a strange thing…
See this rather lengthy thread. All methods discussed there are available in the package bear for R (see here).

❝ Or is including all time points from elimination phase (e.g. 13 i.e. all after Tmax) to get correlation coefficient as close to 1 as possible acceptable?

I don’t think this makes sense. We want to get a reliable estimate of the elimination, not a correlation coefficient as close to 1 as possible. It’s evident that the closer you get to t_max, the more influentual the – still existing – absorption phase will be. But that’s another cup of tea.