You are here:

Pharmaceuticals/Extending API retest date for frozen API's


QUESTION: Hi Michael,
I have a question regarding the retest date for API's stored at -20 degrees Celsius.  Three PVB's were manufacutured Nov 2011 and the three PVB lots were placed on stability studies on Nov 2011.

My question is if we now (Dec 2012) want to sell API from one of these three PVB lots we do not have enough stability data to set a valid retest date.  Our 12 month stability timepoint was completed in Nov 2012 however the batch is now 13 months old and we do not have 18 months stability yet.  

How can the manufacturer set a valid retest date since the stability data will never catch up.  This of course is only an issue for the first three lots placed on stability.   

Any assistance would be appreciated.

ANSWER: Marcello:

If you have accelerated stability data, then based on 12 months accelerated data you can claim a two year expiration date.

If you do not have any accelerated data - what you do is progressively roll out the expiration date. As of today you can only claim a 12 month expiration date; by this time next year you will be able to claim a 24 month expiration date etc.

I hope this helps,
Michael Anisfeld

---------- FOLLOW-UP ----------

QUESTION: Hi Michael,

Thanks for your answer.  We only have three months accelerated at refrigerated conditions so I believe we can only claim a 12 month retest date at the moment based on completed long term stability.

We still have an issue whereby the API from all three PVB's is now 13 months old but we can only state a 12 month retest date based on our 12 month long term and 3 month accelerated stability studies therefore our coa's cannot list a valid retest date since the retest date has tecnically already passed.

Can the manufacturer actually retest the API now at 13 months and then add additional time such as 6 months to the retest date?  Is there any guidance or regulations that will allow for that?  

Our problem is that customers will not accept the API without a valid retest date.

Thanks for any help.

ANSWER: I'm confused - is your concern with the stability/retest date of the API; or the stability/retest date of the finished drug product that the API is used in.

Please clarify so I can respond.

---------- FOLLOW-UP ----------


My question is with the retest date of the actual API, not the finished drug product.  We only have 3 months accelerated at refrigerated conditions and 12 months long term at freezer conditions.  The first three PVB's manufactured are already 13 months old and we are wondering what can be done to set an acceptable valid retest date.
At this point our stability data will not catch up with the manufacture date of the three PVB's so I believe based on our available stability date we cannot place a retest date greater than 12 months.

My question is is it acceptable if the manufacuturer actually retests the three PVB's right now at 13 months and then if the results are good, can they add additional time say another 6 months from the date they actually retested the PVB's?

This must be a common issue for the manufacture of the first three API PVB's and the setting of the initial retest dates since the stability studies usually start right after the three PVB's are manufactured.



I agree with you regarding the retest date assignment, and would go with 12 months based on your current data.

However ... you might be interested in an approach offered by the Canadian GMPs - quote:

"7.1 If any raw material is held in storage after the established re-test date, that raw material is quarantined, evaluated, and tested prior to use. The re-test date or expiry date is based on acceptable stability data developed under predefined storage conditions or on any other acceptable evidence. A batch of raw material can be re-tested and used immediately (i.e., within 30 days) after the re-test as long as it continues to comply with the specifications and has not exceeded its expiry date. A raw material held in storage after the established expiry date should not be used in fabrication"

I hope this helps.


All Answers

Answers by Expert:

Ask Experts


Michael Anisfeld


Disclaimer: SORRY BUT I DO NOT ANSWER QUESTIONS RELATED TO: DRUG ACTIONS/INTERACTIONS, INTERNET DRUG PURCHASES, RESULTS OF DRUG TESTS, IDENTIFYING DRUGS (FOR WHICH YOUR LOCAL PHARMACIST IS THE BEST PERSON TO CONSULT). My expertise is answering questions relating to pharmaceutical manufacturing and quality technologies, drug regulations and specifically GMP requirements


Past/Present Clients
Governments (Australia, Canada, India, United Kingdon, United States
Companies - over 200 companies in 37 countries

©2017 All rights reserved.