Bioequivalence and Bioavailability Forum

Dear IK and HS,

❝ Interesting approach. IMHO once you have validated the method for dilution

❝ integrity, there is no need to run 'DI QCs' (to be honest, never heard this

❝ term before). Don't you have an SOP for such a situation? I would say:

❝    • No need to repeat the batch of subject samples, since QCs passed.

In the validation, you demonstrate that by diluting a sample for example twice the ULQ concentration, the calculated concentration is not compromised. In other words, the ability to dilute a certain concentration is validated using one dilution factor (5 or 10 folds).
However, during sample analysis, by diluting High QCs with the same dilution factor that is applied to subject samples, you are validating the dilution factor you are applying on that day by the same analyst who’s diluting both QCs and subject samples.

❝    • Repeat diluted samples, since DI QCs failed

I agree