Bioequivalence and Bioavailability Forum • My lack of understanding

My lack of understanding [Regulatives / Guidelines]

posted by ElMaestro – Denmark, 2010-05-28 02:54 (5501 d 16:18 ago) – Posting: # 5390
Views: 16,928

Hi GSTAT,

❝ As per my understanding, if i am not wrong FDA wants you to conduct a three way crossover study with two doses of reference and then fitting an Emax model (as given in recommendation) for reference which will provide estimated values of parameters used in model.

❝ Put those estimated values again in model for test product as response and find relative bioavailability (F) of test with respect to reference.

This is more or less also what I can make out of it, but note that the Emax model contains three unknowns: E₀, E_max and ED₅₀ plus of course the relative potency itself.
In order to make a fair fit to that model for ref., you need at least 3+ dose levels, if I am not mistaking?

The only thing I could imagine with two levels of Ref and one level of Test would be:

Construct a straight line through the two Ref points
Measure the vertical distance from the single Test point to the regression line.
Convert the vertical distance, by means of the slope we got from (1), to a horizontal distance, which is then taken as a measure of the relative potency under a sh!tload (pardon my French) of assumptions which cannot be qualified by this design itself.

Somehow I don't get the details of all this.
Can you tell?

Many thanks for clarification and best regards,
EM.

—
Pass or fail!
ElMaestro

Complete thread:

Orlistat Bioequivalence KR 2010-04-23 06:14 [Regulatives / Guidelines]
- To Abreviate or not to Abreviate d_labes 2010-04-23 09:28
  - What was really meant ElMaestro 2010-04-23 09:50
    - OGD Guidance Helmut 2010-04-23 12:42
  - To Abreviate or not to Abreviate KR 2010-04-23 15:01
    - Calm and serene d_labes 2010-04-23 15:47
    - To Abreviate or not to Abreviate ElMaestro 2010-04-24 08:16
      - To Abreviate or not to Abreviate KR 2010-04-26 06:03
        
        To Abreviate or not to Abreviate GSTATS 2010-05-27 18:30
        
        My lack of understandingElMaestro 2010-05-28 00:54
        
        My lack of understanding GSTATS 2010-05-28 17:03
        
        My lack of understanding ElMaestro 2010-05-29 03:32
        
        My lack of understanding GSTATS 2010-05-29 05:28
        
        My lack of understanding KR 2010-05-31 08:51
        
        My lack of understanding ElMaestro 2010-06-01 16:13
        
        Calculation sangeeta 2011-11-29 17:58
        
        Calculation ElMaestro 2011-11-29 18:09
        
        Calculation sangeeta 2011-11-29 18:30
        
        Calculation ElMaestro 2011-11-30 11:35