Bracketing and Matrixing in Stability Study

Dear All,

I have some pending samples for stability analysis. Can I apply Bracketing and Matrixing to reduce the load of testing ?

If not then in which conditions, Bracketing and Matrixing can be applied ?

Kindly do suggest.




Edited Fri, Oct 18, 2013 2:35 PM

Replies to this Topic

My suggestion.

You can do apply the bracketing and matrixing, provided you have to change your stability protocol and should be able to justify the change through documents.

Kindly confirm before application

Thanks Mr Saleem,

But I cannt change the stability protocol by Change Control, since only for the pending batches I need to apply Bracketing and Matrixing.So can I change it through Deviation ?And what kind of justification will be appropiate ?

Kindly suggest . 

 Please note the applicable section below.  Bracketing should not be applied to different formulations of the same API but only different fill or compression weights of the same formulation.



Bracketing can be applied to studies with multiple strengths of identical or closely related formulations. Examples include but are not limited to (1) capsules of different strengths made with different fill plug sizes from the same powder blend, (2) tablets of different strengths manufactured by compressing varying amounts of the same granulation, and (3) oral solutions of different strengths with formulations that differ only in minor excipients (e.g., colourants, flavourings).

With justification, bracketing can be applied to studies with multiple strengths where the relative amounts of drug substance and excipients change in a formulation. Such justification can include a demonstration of comparable stability profiles among the different strengths of clinical or development batches.

In cases where different excipients are used among strengths, bracketing generally should not be applied.




Thanks Mr Ken,

The products meet all the required conditions for Bracketing and Matrixing. My only query is how to change the stability protocol since only for the pending batches , I need to apply Bracketing and Matrixing. Other batches have to be tested  as per the protocol.

So can I change the protocol through Deviation procedure and and what would be the appropriate reason for taking deviation ?

Kindly suggest.





You can fill the event and make a new version of protocol, only if you can state in event that your sample is meets the bracketing or matrixing approach as stated in the ICH Q1D.

First thing is you have to perform the stability analysis within the time frame given in your SOP.

If you are not able to do the analysis with in the time frame, take the required steps mentioned in your SOP.

If the SOP does not mention anything, take the deviation control form and fill the deviation and write the justification. following might be the reasons to justify

1. Non availability of the instrument [ busy or repair]

2. Analyst non availability 

3. Non availability of the standards [late during the procurement] 

if you follow the above, you are not required to change the protocol for including bracketing or matrixing for only those batches.

[Note: Please take care this should be happened within one month time of the schedule date of analysis.]

srikanth N




If these batches are regulatory submission batches its better to change the stability protocol by taking change control and you can justify based on ich q1D

Post Reply

You must be logged in and a member of this Groupsite in order to post a reply to this topic.
To post a reply, contact your group manager(s) Join this Groupsite