Bioequivalence and Bioavailability Forum

Dear Sudeshna,

❝ [%]Stability = 100 x Mean Conc. of Stability Samples /

❝ Mean Conc. of Comparison Samples

True. But for post-preparative stability, keeping an eye on peak areas is a good idea too. If you have a decreased signal for both your analyte and your IS you may still have an acceptable accuracy, but you may end with LLOQ problems.

❝ No need to prepare freshly prepared QC samples along with fresh CC.

There are some discussions there. Some people say you should also prepare fresh QCs along with your fresh CCs. As your stability samples are in fact unknown samples (you don't know if the stability is OK, so you don't really have a nominal concentration any more), they say you should have fresh QC samples to validate your run (3 levels in duplicate, with the usual acceptance rules).

❝ Compare the stability QC samples with first day P&A batch QC samples.

That's what the FDA guideline says. But have a look at the 2007 Crystal City paper: they now recommend to compare to the nominal concentration. Day 0 or day 1 concentrations are rather used to make sure the stability samples were preprared correctly.

Regards
Ohlbe