Long term stability [Bioanalytics]

posted by deepakpangavhane – India, 2019-01-14 14:18 (2013 d 08:35 ago) – Posting: # 19778
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Dear Ohlbe,

❝ ❝ I spiked metabolite for new validated method as study samples contain analyte and metabolite. HQC level of metabolite is spiked in parent analyte during method validation.

❝ It is good to do it at least once, analysing QCs spiked only with the parent + QCs containing parent and metabolite, against calibration samples containing only the parent. This way you can demonstrate the selectivity of your method and the lack of back-conversion during the analysis. But I would not necessarily expect the whole validation to be performed with samples spiked with the metabolite if you don't measure it with the method being validated.

We perform complete validation taking into account fact that- SPE cartridge make change; change in concentration range from 10-5000 pg/mL to 10-4000 pg/mL; parent analyte spiked in plasma in presence of metabolite to mimic study sample plasma conditions; to incorporate recent validation guidance recommendations. To be on safer side...

❝ You did not answer my question on the type of metabolite and risk of back-conversion...

Metabolite is hydroxy form of parent analyte. As evident from validation data, back-conversion during storage was not observed.

❝ If you have long-term stability data of your metabolite showing that there is no back-conversion during storage, I would think you can provide reasonable justification. I would also look at the results of the other stability experiments, particularly freeze/thaw (passing easily, or borderline ?). If in doubt, start a controlled correspondence with the FDA. But with the shutdown, running the stability might be faster

We have LTS data of metabolite showing no back-conversion i.e. LTS data within acceptance to initial day analysis.
We are also thinking to proceed for long term stability experiment for parent analyte with new method for analyte.

Deepak Pangavahne

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