roody
●    

2005-08-30 19:06

Posting: # 25
Views: 15,802
 

 ethnic variations [Power / Sample Size]

Does the variability remains the same in different population (US or Europe/Japan Vs. India) while calculating the sample size for pivotal BE studies? How to overcome the ethnic variations (sample size calculation) in pharmacokinetic studies?
Helmut
★★★
avatar
Homepage
Vienna, Austria,
2005-09-02 13:41

@ roody
Posting: # 26
Views: 11,883
 

 ethnic variations

Dear roody!

» Does the variability remains the same in different population (US or Europe/Japan Vs. India) while calculating the sample size for pivotal BE studies?

I think this a complex issue, even assuming you are not talking about bridging studies (viz. comparisons between different ICH regions)!

If you are talking about cross-over studies, differences between populations – mainly caused by polymorphism – should not be a major problem: e.g., slow metabolizers show higher levels both after test and reference, i.e., the treatment-ratio should be the same as in fast metabolizers.

If you are talking about parallel designs, e.g., for drugs with a long half life, or studies in patients – sample sizes suitable in one population may be entirely insufficient in an other, since the total variability (intra- plus intersubject) may be different.

» How to overcome the ethnic variations (sample size calculation) in pharmacokinetic studies?

It should not be a big problem in cross-over studies, although it may be wise to allow for some ‘safety margin’ in sample size extrapolating from one population to an other.
For parallel designs you should be (very!) weary. For example you can run into analytical problems, if your target population consists mainly of extensive metabolizers…

Cheers,
Helmut Schütz
[image]

The quality of responses received is directly proportional to the quality of the question asked. 🚮
Science Quotes
Activity
 Admin contact
20,249 posts in 4,261 threads, 1,397 registered users;
online 8 (0 registered, 8 guests [including 6 identified bots]).
Forum time (Europe/Vienna): 22:03 CET

To call the statistician after the experiment is done
may be no more than asking him to perform a postmortem examination:
he may be able to say what the experiment died of.    R.A. Fisher

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