January 2023
Real CMC Tips and Insights

published 2 Feb 2023

Since the beginning of July 2020, we have published weekly Regulatory tips and insights from our Regulatory experts on our Real Regulatory LinkedIn page, as a service to our followers. The tips we published in January 2023 are collected here, for convenience. Make sure you follow  Real Regulatory Ltd and Real CMC for regulatory news, reports and hints.


Reporting impurities

ny impurities present above the reporting threshold should be reported individually. Reporting a ‘maximum observed impurity’ provides very little information on the analyte’s impurity profile, especially when trying to observe trends during stability studies. For in-house evaluation, it is preferable to individually report all impurities at or above the LOQ.


Dissolution profiling of biobatches

Study the dissolution profiles of your bioequivalence study batches in as many media using as many different test parameters as possible. Characterisation of biobatch dissolution will form the basis for your dissolution specifications throughout your product’s lifecycle. The more information you collect, the more thankful you’ll be years down the line.


Specifications in the Dossier


Specifications presented in a marketing authorisation application should be numbered and dated. Many assessors will insist on this, and it is good practice in any case, for traceability. It is advisable to create an SOP laying out the numbering system and linking back to in-house specifications.



For polymorphic drug substances, you need to demonstrate that:
1. The same form of the drug substance is consistently synthesized and does not change during the retest period.
2. Conversion to a different form does not occur during finished product manufacture and shelf-life.
If conversion does occur, you will have to show that product performance, safety and efficacy are not affected.




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