Bioequivalence and Bioavailability Forum

Hi All,

Now a days, CROs are recieving frequent queries from FDA (after publishing guidance Bioequivalence Studies With Pharmacokinetic Endpoints for Drugs Submitted Under an ANDA Aug 2021) like as below.


"We acknowledged that you used both male and female subjects in your fasting bioequivalence (BE) study #XXXXXX. However, it was noted that the percentage of male and female are not similar as 82% and 18%, respectively. Per the labeling of reference product, the proposed product is intended for use in both sexes. Therefore, similar proportions of males and females are recommended to be included in the study. Please provide scientific justification to support that the BE results from unbalanced male vs females subjects in the above BE study can be extrapolated to the entire population and that the unbalance male and female subjects in study population will not affect the BE conclusion."


In one of the webinar hosted by FDA where speaker said that FDA is aware that these are crossover studies and overall it may not have significant impact but FDA still wants similar proportions of males and females.


If PK of a drug in male and female are similar then a scientific justification can be drafted.

But how can CRO respond to the query where CRO has not included similar proportion of male and female (obivious reason is unavailability of female volunteers) and PK in male and female are different.


Please feel free to share your experience if anyone has recieved similary queries and what justification was provided.