Bioequivalence and Bioavailability Forum

❝ ❝ 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.

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❝ 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.

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

❝ 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