how intensive shall I go for early phase method validation

[darasc0211]

Hi,

I am in pharmaceutical industry and need to validate an impurity method to support First in Human clinical study. I have two doses with proportional formulations. Here are my 5 quesitons: (Sorry that I am new to validation)

1. for specificity study, at early stage do I need to completely seperate all the impurities that's above LOQ? Or I just need to make sure no interference with API and not worry about the resolution between impurities?
2. Because there is no specified impurities, do I need to perform linearity in matrix?
3. Because there is no specified impurities, do I need to perform recovery?
4. Because this is an impurity method (NOT an Assay method) and I will calculate by area% (not quantitation), do I still need bracket standards?
5. As long as I can prove linearity for example between 80% of low dose and 120% of high, I can use one std to quantitate both strengh. Correct?

Thanks in advance.

[DR]

My knee-jerk reaction is to answer "Yes" to all questions and to note that area % on #4 will probably not be sufficient for long.

That said, I'm not in Regulatory, so you should consult with them prior to your clinical trial's initiation.