Interesting what Artificial Intelligence turns up with this question (below, with no source given). “Arti” seems to think that a Period After Opening represents a viable period of stability no matter when it begins because you have PAO data (from before expiry on 2 other batches). While it’s of interest to see where the data goes following an expiry period, Expiry is Expiry and it only makes sense to do a Use Test on unexpired material. We don’t want the consumer to be using an expired product.
That said, should we take our third batch and start a 30 day use test 30 days before expiry? Since you may need time to conduct an investigation or perform a retest, it would make more sense to do this test at least 3 months before expiry to be sure of wrapping up everything in good order prior to the expiration date.
AI Overview
The “in-use” portion of a product typically begins before the expiry date. The product’s period after opening (PAO) is the time it can be safely used after the product is first opened, which is separate from the expiry date. So, the final opening should occur before the expiry date, and the use period after that opening extends for the PAO duration, which may or may not go beyond the expiry date.
