Bioequivalence and Bioavailability Forum

Dear Virendra,

first see this post.
For others you may search the forum.

❝ As per my experiance - If the screening period is short than chances of rejection of subjects is less in enrollment of study (on medical ground).

❝ If i m right than why people are using different criteria?

A longer screening period means less rejected subjects and consequently is cheaper in the long run. The price you will pay is less confidence that subjects are really healthy at the first treatment.

Example:
Average rejection rate 33%
Expected minimum / maximum rejection rates 25% / 50%
Sample size 24 subjects
Reserves 10%

In order to have 26 healthy subjects available for dosing, we will screen 35 subjects on average (minimum 33, maximum 39).
If we have a longer screening period we will screen the average number in the long run, but if we screen subjects just one day before administration, we cannot aim for the average, but rather the maximum expected rejection rate (otherwise there is a fairly high chance of less than needed eligible subjects...).

❝ Is there any guideline or reference suggesting the criteria?

IMHO, still no.