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Vd/F calculation in bear [R for BE/BA]

posted by CECIF - Colombia, 2017-11-02 22:45  - Posting: # 17964
Views: 2,992

Hello everybody

I have been using bear for bioequivalence calculation since version 6.2. I consider it very useful and approachable and I am really grateful with yjlee168 for it.

For regulations in my country I have to make my own validation of bear's estimates. therefore I have been using a study of my own and I comapre my result with the ones I got from bear with the same study. Most of the values came out quite well, on exception of some of the AUC0inf and AUC0t mostly on the last sampling times which came out a little higher in my calculations (I can only suposse it is because of the decimal numbers).

However, the one parameter I have been struggling to get right in any way was Vd/F. Therefore I really need to ask what method bear uses to calculate it. I have been trying different equations to get it, but I failed in every one.
is it Vd/F= D*Ka/(I(Ka-Ke))? with ka from the residuals method or the wagner-nelson method?
or is it simply Vd/F=D/(AUC0inf*Ke)?
Vd/F= Apparent volume of distribution
I=intercept of the concentration vs time graph (x=0) when extrapolating the excretion line
ke=elimination constant (lambda z)
ka=absortion constant

Feel free to correct any missconception from my equations too.

I would really appreciate any light you could shed on this matter.

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