Bioequivalence and Bioavailability Forum

Dear Shweta!

❝ Why it should be carried out as new LQC having conc that is already proved

❝ in to previous calibration range.

I guess Marko was referring to FDA's guideline. Stability experiments shoud be carried out at the 'low and high concentrations' (Section IV.D. Stability, pp 6-7). The concentration of the low QC sample should lie 'within 3× the lower limit of quantification' (Section F. Specific Recommendations for Method Validation, p 13).
Since you changed your LLOQ, your low QC should also move down. This requirement is reasonable, because for instance irreversible absorption to the container/stopper may hit you only at lower concentrations.