Bioequivalence and Bioavailability Forum

Dear Sir,

I received below mentioned reply in my mail but it is not reflecting in the forum. I don't know how?

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Dear Manoj,

❝ ...i selected time points manually for calculation of

❝ Lamda_z in such a way that Rsq value comes at least above 0.8

Maybe it only comes from the wording you use, but I don't like the sound of that. And that's exactly where you may run into trouble with regulators, especially in the case of an inspection .

When BE guidelines tell you that AUC_0-t should cover at least 80 % of AUC_0-inf, it means that you should design your trial in such a way that it will be at least 80 % (adapting sampling duration and LLOQ); not that you should cook your data till it gets to at least 80 %, selecting points that would belong to the ditribution phase and not to the terminal elimination phase in order to reduce t_1/2 and % extrapolation.

Have a look at this thread for previous discussions on half life calculations.

Regards
Ohlbe
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Answering to above mentioned reply

I understand that it might not be the right way but software may also select the wrong time points for calculation and that might be the reason for erratic results i am getting. And There may be some logic behind providing such feature (manual selection of time point for calculation of elimination rate constant)in the software. So again my question is that how to decide those time points.

I wanted to further add some information about the study i conducted. I have measured the concentration up to 48 hr but in most of the subjects we were able to detect the concentration upto 10 hr above LOQ (0.3 ug/ml) and after 6 hr concentration is less than 1 ug/ml in most of the subject. But sometimes some subject have plasma concentration above LOQ after 10 hr also. That is briefly about the pharmacokinetic of drug. Let me know if you need further any information about the kinetic of drug.

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Edit: Broken links removed, order altered for clarity. [Helmut]