Drug concentration <LLQ [Bioanalytics]

posted by Ohlbe – France, 2018-06-29 14:00 (2155 d 17:16 ago) – Posting: # 18995
Views: 2,871

(edited by Ohlbe on 2018-06-29 17:11)

Dear GM,

❝ As per the Bioanalytical guidance of FDA, all values <LLQ should be declared as zero.


❝ But my doubt is, is there any possibility to use the actual values measured for calculating key parameters?


In BE ? Not the slightest. Nada. Forget it.

❝ B’coz, we are not getting best fit (Rsq<0.8) when considering zero instead of actual values.


So what ? Who says it has to be < 0.8 ?

The question is rather: was your LLOQ low enough ? What you're describing sounds a bit like you're not able to follow the terminal elimination phase but are getting a mix of distribution + elimination. If you messed up, you can't make up for it by extrapolating below your LLOQ, you'll have to re-develop your method, validate, re-assay.

What is your LLOQ, and what is the Cmax range in your study ?


Edit, to make sure there is no misunderstanding: when you write

❝ B’coz, we are not getting best fit (Rsq<0.8) when considering zero instead of actual values.

I hope you're not using these values as 0 to calculate Kel, right ? These sampling points should just be ignored. They were to be reported as 0 in the tables of the concentration in the report, not to be used as 0 in the calculations. As pointed out by Helmut, in any case they now have to be reported as BQL. [Ohlbe]

Regards
Ohlbe

Complete thread:

UA Flag
Activity
 Admin contact
23,035 posts in 4,835 threads, 1,645 registered users;
42 visitors (0 registered, 42 guests [including 5 identified bots]).
Forum time: 07:17 CEST (Europe/Vienna)

The mediocre teacher tells.
The good teacher explains.
The superior teacher demonstrates.
The great teacher inspires.    William Arthur Ward

The Bioequivalence and Bioavailability Forum is hosted by
BEBAC Ing. Helmut Schütz
HTML5